magnetic recording media

Abstract

The purpose of the present invention is to provide a magnetic recording medium which exhibits a high Signal-to-Noise Ratio (SNR), and has excellent thermal stability. 　The present invention provides a tape-shaped magnetic recording medium comprising a recording layer, a CAP layer, and a protection layer, in this order. The recording layer has a ratio in terms of the average number of atoms represented by formula (I): [Co(100-X-Y)PtXCrY](100-Z) – (MON)Z, where 10 ≤ X ≤ 25, 8 ≤ Y ≤ 16, and 6 ≤ Z ≤ 11, and MO N is a metal oxide.　In the tape-shaped magnetic recording medium, the ratio Δθ50 / (p+q), where p represents the height [nm] of 0.1% area, in the direction of surface convexity, in a bearing curve created on the basis of height data of a surface on the protection layer side acquired by using an atomic force microscope, q represents the average thickness [nm] of the protection layer, and Δθ50 represents a half-value width of a rocking curve of a CoPtCr hcp (0002) peak obtained by X-ray diffraction carried out in an out-of-plane direction of the recording layer, is 0.360 to 0.545, and the average thickness of the CAP layer is 4 nm or more.

Description

[Technical Field]

[0001] The present technology relates to magnetic recording media. [Background technology]

[0002] Typical magnetic recording media include magnetic recording tape and hard disk media. In recent years, the former, magnetic recording tape, has been attracting renewed attention for its use in data uploading. This is because the amount of information to be recorded over the long term has increased explosively due to the widespread use of the Internet, the use of cloud computing, and the accumulation and analysis of big data, creating a demand for magnetic recording media with higher recording capacities. Furthermore, magnetic recording tape offers advantages in terms of cost, energy savings, long life, and reliability.

[0003] As the recording capacity of magnetic recording media increases, there is a demand for improving the signal-to-noise ratio (SNR) to achieve higher recording density. Several technologies have been proposed to increase the SNR of magnetic recording media. For example, Patent Document 1 below discloses a magnetic recording medium in which a magnetic film mainly composed of Co-Pt-Cr and containing Si oxide is formed on a substrate, and the content of the Si oxide is 8 atomic % or more and 16 atomic % or less, calculated as Si atoms, relative to the Co-Pt-Cr. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-342908 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to reduce noise and improve the SNR, it is conceivable to miniaturize the magnetic material contained in the magnetic recording medium. However, miniaturization of the magnetic material may reduce the thermal stability of the magnetic recording medium, which may result in the recording information not being stably retained. In order to stably retain the recorded information, the magnetic recording medium is also required to have excellent thermal stability. Therefore, a main object of the present technology is to provide a magnetic recording medium that exhibits a high SNR and excellent thermal stability. [Means for solving the problem]

[0006] This technology is The optical disc has a recording layer, a CAP layer, and a protective layer in this order, The recording layer has an average atomic ratio represented by the following formula: [Co (100-X-Y) Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the formula (I), 10≦X≦25, 8≦Y≦16, and 6≦Z≦11; and MO N indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 and the ratio Δθ 50 / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The average thickness of the CAP layer is 4 nm or more. A tape-shaped magnetic recording medium is provided. The magnetic recording medium may have a base layer, a seed layer, and an underlayer in this order, and the recording layer may be provided on the underlayer. The underlayer may have a first underlayer and a second underlayer, and the recording layer may be provided on the first underlayer. The seed layer may include a first seed layer and a second seed layer, and the underlayer may be provided on the first seed layer. The magnetic recording medium may have an intermediate layer, and the intermediate layer may be provided between the underlayer and the recording layer. The magnetic recording medium may have a SUL, and the SUL may be provided between the base layer and the seed layer. MO in the formula (I) N may be at least one selected from B2O3, SiO2, and TiO2. The CAP layer may include an alloy including Co, Pt, Cr, and B. The underlayer may contain ruthenium. The first seed layer may include a nickel-tungsten alloy. The second seed layer may include an alloy including Ti, Cr, and O. The recording layer may have an average thickness of 10 nm or more and 20 nm or less. The protective layer may have an average thickness of 1 nm or more and 10 nm or less. The first underlayer may have an average thickness of 1 nm or more and 30 nm or less. The second underlayer may have an average thickness of 1 nm or more and 50 nm or less. The first seed layer may have an average thickness of 1.0 nm or more and 20.0 nm or less. The second seed layer may have an average thickness of 0.1 nm or more and 5.0 nm or less. This technology is The optical disc has a recording layer, a CAP layer, and a protective layer in this order, The recording layer has an average atomic ratio represented by the following formula: [Co (100-X-Y) Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the formula (I), 10≦X≦25, 8≦Y≦16, and 6≦Z≦11; and MO N indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 and the ratio Δθ 50 / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The CAP layer has an average thickness of 4 nm or more, and the magnetic recording medium is in the form of a tape. The magnetic recording medium is accommodated in a state of being wound around a reel. A magnetic recording cartridge is also provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a schematic diagram showing a recording head and a magnetic recording medium. [Figure 2] FIG. 2 is a schematic diagram showing a recording magnetic field generated by a recording head. [Figure 3] 1 is a diagram showing an example of a layer structure of a magnetic recording medium according to a first embodiment. [Figure 4] 1 is a graph showing an example of a bearing curve; [Figure 5] FIG. 6 is a diagram showing an example of a layer structure of a magnetic recording medium according to a second embodiment. [Figure 6] FIG. 10 is a diagram showing an example of a layer structure of a magnetic recording medium according to a third embodiment. [Figure 7] FIG. 1 is a schematic diagram showing the configuration of a recording / reproducing device. [Figure 8] FIG. 2 is an exploded perspective view showing an example of the configuration of a magnetic recording cartridge. [Figure 9] FIG. 2 is a block diagram showing an example of the configuration of a cartridge memory. [Figure 10] FIG. 10 is an exploded perspective view showing an example of the configuration of a modified magnetic recording cartridge. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments for implementing the present technology will be described below with reference to the accompanying drawings. Note that the embodiments described below are intended to exemplify preferred embodiments and variations of the present technology, and are not limited to these. Various variations based on the technical concepts of the present technology are possible. For example, the configurations, methods, steps, shapes, materials, and numerical values ​​described in the following embodiments and variations thereof are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values ​​may be used as necessary. Furthermore, when a chemical formula of a compound or the like is given, this chemical formula is a representative one, and is not limited to the stated valence, etc., as long as it is a general name for the same compound. Furthermore, the configurations, methods, steps, shapes, materials, and numerical values ​​described below and their variations can be combined with each other as long as they do not deviate from the spirit and scope of the present technology. The description will be given in the following order.

[0009] 1. Magnetic recording media using this technology (1) Overview (2) Composition of the recording layer (3) Ratio Δθ 50 / (p+q) (4) Average thickness of the CAP layer (5) Layer composition 2. First embodiment (1) Structure of magnetic recording medium (2) Explanation of each layer (3) Effects 3. Second embodiment (1) Structure of magnetic recording medium (2) Explanation of each layer 4. Third Embodiment (1) Structure of magnetic recording medium (2) Explanation of each layer 5. Manufacturing method of magnetic recording medium 6. Recording and playback equipment 7. Magnetic Recording Cartridge 8. Modified Magnetic Recording Cartridge 9. Working Example

[0010] 1. Magnetic recording media using this technology

[0011] (1) Overview

[0012] The magnetic recording medium of the present technology has a recording layer, a CAP layer, and a protective layer in this order. The recording layer has an average atomic ratio represented by the following formula (I). [Co (100-X-Y) Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the above formula (I), 10≦X≦25, 8≦Y≦16, 6≦Z≦11, and MO N indicates a metal oxide.) The magnetic recording medium of the present technology has a recording layer with the specific composition described above, and therefore has a high signal-to-noise ratio (SNR) and excellent thermal stability.

[0013] The magnetic recording medium of the present technology has a height p [nm] of 0.1% area in the surface convex direction in a bearing curve created based on height data of the surface on the protective layer side obtained using an atomic force microscope, an average thickness q [nm] of the protective layer, and a half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 and the ratio Δθ 50 / (p+q) is 0.360 or more and 0.545 or less. 50 When / (p+q) is within this range, a high SNR is exhibited.

[0014] The magnetic recording medium of the present technology has an average thickness of the CAP layer of 4 nm or more. Because the magnetic recording medium of the present technology has an average thickness of the CAP layer of 4 nm or more, it exhibits a high SNR and can reduce the saturation magnetic field (Hs). This reduction in the saturation magnetic field (Hs) can prevent difficulty in recording information on the magnetic recording medium.

[0015] The magnetic recording medium of the present technology is in the form of a tape, and may be, for example, a long magnetic recording tape. The tape-shaped magnetic recording medium of the present technology may be housed in, for example, a magnetic recording cartridge. More specifically, the magnetic recording medium may be housed in the cartridge in a state where it is wound around a reel within the magnetic recording cartridge.

[0016] Composition of the recording layer and ratio Δθ in the magnetic recording medium of the present technology 50 / (p+q), the average thickness of the CAP layer, and the layer configuration are further explained below.

[0017] (2) Composition of the recording layer

[0018] High areal density (e.g., 100 Gb / in 2 To achieve the above areal recording density, a magnetic recording medium with low noise and high SNR is required. One possible way to reduce noise is to miniaturize the magnetic material contained in the magnetic recording medium. However, miniaturizing the magnetic material makes the magnetization recorded on the magnetic recording medium (specifically, the recording layer) more susceptible to attenuation by thermal energy. This magnetization attenuation can make it difficult to stably retain information recorded on the magnetic recording medium (specifically, the recording layer). As such, miniaturizing the magnetic material reduces the thermal stability of the magnetic recording medium, which can lead to the recording information not being stably retained. Therefore, magnetic recording media are also required to have excellent thermal stability.

[0019] As an index of the thermal stability of magnetic recording media, K u V act / k B There is a T. K u is the magnetic anisotropy energy of the magnetic material, V act is the activation volume of the magnetic material, k B is the Boltzmann constant and T is the absolute temperature. u V act / k B The higher the T value, the higher the thermal stability of the magnetic recording medium. In order to stably retain recorded information in the magnetic recording medium, it is necessary to prevent the above-mentioned decrease in thermal stability. Therefore, the Ku V act / k B It is desirable that the value of T be equal to or greater than a certain value.

[0020] Thus, in order to increase the areal recording density of magnetic recording media, it is necessary to reduce noise (i.e., improve SNR), but miniaturizing the magnetic material to reduce noise (to improve SNR) tends to reduce thermal stability. Therefore, it is not easy to achieve both improved SNR and improved thermal stability at the same time.

[0021] The present inventors have investigated a magnetic recording medium that exhibits a high SNR required for realizing a high areal recording density and also has excellent thermal stability. 2 In order to stably retain recorded information on magnetic recording media with an areal recording density of K u V act / k B Therefore, the inventors have considered that T is desirable to be 80 or more. 2 It exhibits the high SNR required to achieve an areal density of 1000 or more, and also has a K u V act / k B Further studies were carried out on magnetic recording media having a T of 80 or more. As a result, the inventors discovered that the SNS can be improved and the K u V act / k B It was found that it was possible to increase T to 80 or more. [Co (100-X-Y) Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the formula (I), 10≦X≦25, 8≦Y≦16, and 6≦Z≦11; and MO N indicates a metal oxide.)

[0022] (3) Ratio Δθ 50 / (p+q)

[0023] To achieve high recording density, it is necessary to improve the SNR of magnetic recording media. Typical examples of magnetic recording media include hard disk drives (HDDs) and magnetic tape (tape-type magnetic recording media). To improve SNR, HDDs employ disk media with a so-called CAP layer, which reduces the saturation field, on a magnetic film structure with high magnetic isolation achieved by a material with high magnetic anisotropy. To achieve high recording density in HDDs equipped with such disk media, it is important to minimize the magnetic spacing (magnetic gap). Magnetic spacing is the distance between the recording head element and the magnetic layer surface of the disk media. Previous HDD technologies have achieved magnetic spacings of less than 10 nm. To achieve high recording density, it is also important to use perpendicular magnetic recording technology, which combines a soft magnetic underlayer (SUL) and a single-pole (SPT) recording head. This technology maximizes the characteristics of perpendicular magnetic recording by providing an SUL on the disk media and generating a strong perpendicular magnetic field through the interaction between the SUL and the SPT recording head.

[0024] On the other hand, it is difficult to reduce the magnetic spacing of magnetic tape to the same level as that of HDDs. This is because it is difficult to reduce the thickness of the protective layer of the magnetic tape and the protective layer of the recording head, which are included in the magnetic spacing, to the same level as that of HDDs. The difference in the thickness of the protective layers of magnetic tape and HDDs is due to the different recording methods used in magnetic tape and HDDs. Specifically, in the case of magnetic tape, information is recorded while the magnetic tape and the recording head are in contact with each other. In contrast, in the case of HDDs, information is recorded without contact between the media and the recording head (i.e., with a gap (flying gap) maintained between the media and the recording head). Therefore, unlike in HDDs, the protective layers provided on the magnetic tape and the recording head must be thick enough to prevent wear due to contact between the magnetic tape and the magnetic head. Therefore, the protective layers of the magnetic tape and the recording head must be thicker than those in HDDs. Therefore, it is difficult to reduce the protective layers of the magnetic tape and the recording head to the same level as that of HDDs.

[0025] Furthermore, it is considered difficult to immediately adopt the combination of SUL and SPT recording heads in magnetic tape from both a technical and cost perspective.

[0026] As such, it may be difficult to immediately apply the configuration adopted in HDDs to improve the SNR to tape-type magnetic recording media. Therefore, the inventors have investigated techniques for improving the SNR of tape-type magnetic recording media, and have developed a method for improving the SNR of tape-type magnetic recording media by using three parameters, Δθ 50 We focused on p, and q.

[0027] The three parameters mentioned above will be explained. Parameter Δθ 50 ("Half-width Δθ 50 ") is the half-width of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 The smaller the value, the smaller the degree of dispersion of the c-axis orientation of the CoPtCr-based alloy contained in the recording layer.

[0028] Parameter p (also referred to as "height p of 0.1% area in the surface convex direction") is the height (unit: nm) of 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface of a magnetic recording medium obtained using an atomic force microscope. The height p of 0.1% area in the surface convex direction is a parameter that reflects the tendency of height variations of protrusions present on the surface of the recording layer in the magnetic recording medium of this technology. It is considered that the smaller the height p of 0.1% area in the surface convex direction, the lower the overall protrusions present on the surface of the recording layer. Parameter q (also referred to as "average thickness q of the protective layer") is the average thickness (unit: nm) of the protective layer. The sum (p+q) of the height p of 0.1% area in the surface convex direction and the average thickness q of the protective layer is a parameter that reflects the tendency of long and short distances between the surface of the recording head and the recording layer of the magnetic recording medium. It is considered that the smaller the value of (p+q), the shorter the distance between the recording head and the recording layer.

[0029] The 0.1% area height p in the surface convex direction and the average thickness q of the protective layer will be further described with reference to FIG. 1. FIG. 1 is a schematic diagram showing a recording head 510 and a magnetic recording medium 520. The magnetic recording medium 520 is an example of a typical tape-shaped magnetic recording medium. In FIG. 1, the magnetic recording medium 520 has, in order from the recording head 510 side, a protective layer 530 and a magnetic layer 540. The protective layer 530 corresponds to the protective layer in the magnetic recording medium of the present technology, and the magnetic layer 540 corresponds to the recording layer in the magnetic recording medium of the present technology. The magnetic recording medium 520 further has a base layer (not shown) below the magnetic layer 540. A plurality of protrusions present on the surface of the base layer form a plurality of protrusions 541 on the surface of the magnetic layer 540, and a plurality of protrusions 531 are also formed on the surface of the protective layer 530. A surface 510a of the recording head 510 is in contact with the protective layer 530. Note that the protrusion 541 shown in FIG. 1 is an example of one of the multiple protrusions present on the surface of the magnetic layer 540, and the protrusion 531 is an example of one of the multiple protrusions present on the surface of the protective layer 530.

[0030] When the height p of the 0.1% area in the surface convex direction of the magnetic recording medium of the present technology is applied to the magnetic recording medium 520 of FIG. 1, it is believed that the smaller the value of p, the lower the overall protrusions present on the surface of the magnetic layer 540. When the average thickness q of the protective layer in the magnetic recording medium of the present technology is applied to the magnetic recording medium 520 of FIG. 1, q is the average thickness of the protective layer 530. When the sum (p+q) of p and q is applied to the magnetic recording medium 520 of FIG. 1, it is believed that the smaller the value of (p+q), the shorter the distance between the surface 510a of the recording head 510 and the magnetic layer 540.

[0031] Referring to FIG. 2, the half-width Δθ 50 and (p+q) will be explained. FIG. 2 is a schematic diagram showing the recording magnetic field generated by the recording head 510, and illustrates the case where information is recorded on a perpendicular magnetic recording medium by the recording head 510. The recording head 510 is an example of a ring-type recording head. In FIG. 2, the arrow D h1 ~D h5 indicates the recording magnetic field generated by the recording head 510, and arrow D m indicates the c-axis direction of the magnetic crystal grains 542 contained in the recording layer of the perpendicular magnetic recording medium. The recording magnetic field generated by the recording head 510 is indicated by arrow D h1 The horizontal component shown in and D h2 ~D h5 2, the magnetic field component parallel to the recording layer decreases the further away from the surface 510a of the recording head 510 (i.e., closer to the recording layer of the perpendicular magnetic recording medium), while the magnetic field component oblique to the recording layer increases. Therefore, it is considered that recording efficiency is higher when the recording magnetization direction of the recording layer is partially oblique to the recording layer rather than entirely perpendicular to the recording layer (thickness direction of the recording layer). In other words, the c-axis direction D of the magnetic crystal grains 542 contained in the recording layer m It is believed that the recording efficiency is higher when some of the magnetic crystal grains are oblique to the recording layer than when all of the magnetic crystal grains are perpendicular to the recording layer. Therefore, it is believed that the degree of dispersion of the c-axis orientation of the magnetic crystal grains affects the recording efficiency. Adjusting the degree of dispersion of the c-axis orientation is thought to be effective in improving the recording efficiency.

[0032] Furthermore, the proportion of oblique magnetic field components contained in the recording magnetic field can vary depending on the distance between the surface 510a of the recording head 510 and the recording layer of the magnetic recording medium. Therefore, the degree of dispersion of the c-axis orientation, which can improve recording efficiency, can be affected by the distance between the surface 510a of the recording head 510 and the recording layer of the magnetic recording medium.

[0033] As mentioned above, the half-width Δθ 50 is a parameter that indicates the degree of dispersion of the c-axis orientation of the CoPtCr alloy contained in the recording layer, and (p+q) is a parameter that reflects the tendency of the distance between the surface of the recording head and the recording layer of the magnetic recording medium. 50 It is believed that adjusting the values ​​of (p+q) and (p+q) will improve the recording efficiency. The improvement in recording efficiency can contribute to the improvement of the SNR of the magnetic recording medium. As a result of further investigation, the inventors of the present invention found that the half-width Δθ 50 Δθ, which is the ratio of (p+q) 50 It has been found that a magnetic recording medium exhibiting a high SNR can be obtained by setting / (p+q) to 0.360 or more and 0.545 or less.

[0034] (4) Average thickness of the CAP layer

[0035] The magnetic recording medium of the present technology has a CAP layer. The average thickness of the CAP layer is 4 nm or more. If the CAP layer is less than 4 nm, it becomes difficult to obtain a good SNR.

[0036] Furthermore, the magnetic recording medium of this technology has a CAP layer of 4 nm or more, which reduces the saturation magnetic field (Hs) of the recording layer. The saturation magnetic field (Hs) is the magnetic field required to saturate the magnetization of the magnetic material contained in the recording layer. In order to perform saturation recording using a recording head, the recording magnetic field generated by the recording head must be greater than the saturation magnetic field. Therefore, if the saturation magnetic field is too high, it may become difficult for the recording head to record (write). Reducing the saturation magnetic field (Hs) contributes to preventing recording from becoming difficult.

[0037] (5) Layer composition

[0038] The magnetic recording medium of the present technology has a recording layer, a CAP layer, and a protective layer in this order. The magnetic recording medium of the present technology may further have a base layer, a seed layer, and an underlayer in this order, and the recording layer may be provided on the underlayer.

[0039] The underlayer has one or more layers. The underlayer preferably has a two-layer structure having a first underlayer and a second underlayer. That is, the underlayer preferably consists of a first underlayer and a second underlayer. When the underlayer has a first underlayer and a second underlayer, the recording layer may be provided on the first underlayer.

[0040] The seed layer has one or more layers. The seed layer preferably has a two-layer structure having a first seed layer and a second seed layer. That is, the seed layer preferably consists of a first seed layer and a second seed layer. When the seed layer has a first seed layer and a second seed layer, an underlayer may be provided on the first seed layer.

[0041] When the magnetic recording medium of the present technology has a base layer, a seed layer, and an underlayer in this order, the magnetic recording medium may further have an intermediate layer. The intermediate layer may be provided between the underlayer and the recording layer.

[0042] When the magnetic recording medium of the present technology has a base layer, a seed layer, and an underlayer in this order, the magnetic recording medium may further have a soft magnetic underlayer (SUL), which may be provided between the base layer and the seed layer.

[0043] 2. First embodiment

[0044] (1) Structure of magnetic recording medium

[0045] The configuration of a magnetic recording medium according to a first embodiment will be described. In the description herein, the protective layer side of the magnetic recording medium is referred to as the upper side, and the back layer side of the magnetic recording medium is referred to as the lower side. Layers common to all embodiments of the present technology are indicated by the same reference numerals in all accompanying drawings, and duplicated descriptions of common configurations, materials, etc. will be omitted as appropriate.

[0046] (1-1) Overall structure

[0047] The overall configuration of the magnetic recording medium T1 according to the first embodiment will be described with reference to FIG. 3. The magnetic recording medium T1 is, for example, a magnetic recording medium for perpendicular magnetic recording. The magnetic recording medium T1 includes a back layer 6, a base layer 5, a second seed layer 42, a first seed layer 41, a second underlayer 32, a first underlayer 31, a recording layer 1, a CAP layer C, a protective layer P, and a lubricant layer L, in this order. That is, in the magnetic recording medium T1, the second seed layer 42 and the first seed layer 41 are provided, in this order, on one major surface of the elongated base layer 5. The second underlayer 32 and the first underlayer 31 are provided, in this order, on the first seed layer 41. The recording layer 1, which functions as a magnetic recording layer, is provided on the first underlayer 31. The CAP layer C, the protective layer P, and the lubricant layer L are provided, in this order, on the recording layer 1. The back layer 6 is provided on the other major surface of the base layer 5. The seed layer 4 has a two-layer structure consisting of a first seed layer 41 and a second seed layer 42. The underlayer 3 has a two-layer structure consisting of a first underlayer 31 and a second underlayer 32.

[0048] The second seed layer 42, the first seed layer 41, the second underlayer 32, the first underlayer 31, the recording layer 1, the CAP layer C, and the protective layer P may be vacuum thin films such as layers formed by sputtering (hereinafter also referred to as "sputtered layers"). The magnetic recording medium T1 has an elongated shape and runs in the longitudinal direction during recording and reproduction.

[0049] The magnetic recording medium T1 is suitable for use as a storage medium for data archives, a field recording density of which is expected to increase in the future. This magnetic recording medium T1 has an areal recording density of 100 Gb / in, which is more than 10 times that of current coated magnetic recording media for storage. 2 When a data cartridge of a general linear recording system is constructed using a magnetic recording medium T1 having such an areal recording density, a large capacity of 200 TB or more can be recorded per data cartridge.

[0050] The magnetic recording medium T1 is suitable for use in a recording / reproducing device (a recording / reproducing device for recording and reproducing data) having a ring-type recording head and a giant magnetoresistive (GMR) or tunneling magnetoresistive (TMR) reproducing head. That is, the magnetic recording medium T1 may be a magnetic recording medium for a recording / reproducing device having a ring-type recording head and a GMR or TMR reproducing head. The magnetic recording medium T1 preferably uses a ring-type recording head as a servo signal write head. Data signals may be perpendicularly recorded on the recording layer 1, for example, by a ring-type recording head. Servo signals may also be perpendicularly recorded on the recording layer 1, for example, by a ring-type recording head. That is, the magnetic recording medium T1 may be a magnetic recording medium having a recording layer 1 on which data signals and servo signals are perpendicularly recorded by a ring-type recording head.

[0051] Average thickness t of magnetic recording medium T1 T is preferably 5.6 μm or less, more preferably 5.5 μm or less, and even more preferably 5.3 μm or less, 5.2 μm or less, 5.0 μm or less, or 4.6 μm or less. Because the magnetic recording medium T1 is so thin, for example, the length of tape wound into one magnetic recording cartridge can be made longer, thereby increasing the recording capacity per magnetic recording cartridge. The average thickness t of the magnetic recording medium T1 Tmay be, for example, 3.0 μm or more, 3.2 μm or more, 3.4, or 3.5 μm or more.

[0052] Average thickness t of magnetic recording medium T1 T is obtained as follows. First, a 1 / 2-inch wide magnetic recording medium T1 housed in a cartridge is unwound and cut into 250 mm lengths from three positions, 10 to 20 m, 30 to 40 m, and 50 to 60 m from one end of the outermost periphery, to prepare three samples. Next, using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, the thickness of each sample is measured at five positions, and these measurements (15 points in total) are simply averaged (arithmetic mean) to obtain the average value t T The measurement position is selected randomly from the sample.

[0053] The width of the magnetic recording medium T1 can be, for example, 5 mm to 30 mm, particularly 7 mm to 25 mm, more particularly 10 mm to 20 mm, and even more particularly 11 mm to 19 mm.

[0054] The length of the magnetic recording medium T1 may be, for example, 500 m to 1500 m, and may be, for example, 1000 m or more. For example, the tape width according to the LTO8 standard is 12.65 mm, and the length is 960 m.

[0055] (1-2) Ratio Δθ 50 / (p+q)

[0056] The magnetic recording medium T1 has a half-width Δθ 50 The ratio Δθ is composed of the height p [nm] of the 0.1% area in the surface convex direction and the average thickness q [nm] of the protective layer. 50 The ratio Δθ / (p+q) is 0.360 or more and 0.545 or less, preferably 0.380 or more and 0.540 or less, and more preferably 0.400 or more and 0.500 or less. 50 By setting / (p+q) within this range, the SNR can be improved. 50We will explain the three parameters that make up / (p+q).

[0057] (1-2-1) Half width Δθ 50

[0058] Half width Δθ 50 is the half-width of the rocking curve of the CoPtCr hcp(0002) peak in the X-ray diffraction of the recording layer 1 in the out-of-plane direction. That is, the half-width Δθ 50 is the half-width of the rocking curve obtained by measuring the rocking curve on the (0002) plane of the hexagonal close-packed (hcp) structure of the CoPtCr alloy using X-ray diffraction in the out-of-plane direction of the recording layer 1.

[0059] Half width Δθ 50 is 0.360≦Δθ 50 / (p+q)≦0.545, and preferably 0.380≦Δθ 50 / (p+q)≦0.540, and more preferably 0.400≦Δθ 50 The value satisfies / (p+q)≦0.500. 50 is the ratio Δθ 50 The half width Δθ can be adjusted depending on the values ​​of the other parameters (p and q) so that / (p+q) satisfies the above numerical range. 50 The half width Δθ may be, for example, 3.5° or more and 7.5° or less, 4.0° or more and 7.0° or less, or 4.0° or more and 6.5° or less. 50 can be adjusted, for example, by changing the average thickness of the underlayer 3 or the average thickness of the seed layer 4.

[0060] Half width Δθ 50is calculated as follows. First, a 12.7 mm wide magnetic recording medium T1 is cut into a 30 mm long piece to prepare a rectangular sample measuring 12.7 mm x 30 mm. Furthermore, identically shaped samples are prepared at two locations every 10 m, for a total of three samples. Next, an X-ray diffractometer (Rigaku Corporation, RINT 2000) is used to measure the (θ-2θ) characteristics under the conditions listed in Table 1 below using out-of-plane measurement, a method for evaluating lattice planes parallel to the sample surface of each sample.

[0061] [Table 1]

[0062] The incident X-ray is fixed at 2θ: 43.7° (CoPtCr hcp (0002 plane)), and the X-ray detector is scanned in the range of ±15°. In the diffraction X-ray curve (rocking curve) obtained by the scan, a value that is half the peak intensity is obtained. The values ​​obtained for the three samples are simply averaged (arithmetic mean) to obtain Δθ 50 From the diffraction X-ray curve, Δθ 50 The data processing software used to calculate the value of can be the included peak search software and the XRD analysis processing software JADE.

[0063] (1-2-2) 0.1% area height p of the surface convex direction

[0064] The height p of the 0.1% area in the surface convex direction is a numerical value in a bearing curve created based on height data of the protective layer side surface of the magnetic recording medium T1 obtained using an atomic force microscope. Note that the "protective layer side surface of the magnetic recording medium" refers to the surface of the tape-shaped magnetic recording medium that is closest to the protective layer. For example, even if a layer other than the protective layer (e.g., a lubricant layer) exists on the outermost surface of the magnetic recording medium, the surface closest to the protective layer is referred to as the "protective layer side surface" in this specification.

[0065] The height p of 0.1% area in the surface convex direction is 0.360≦Δθ 50 / (p+q)≦0.545, and preferably 0.380≦Δθ 50 / (p+q)≦0.540, and more preferably 0.400≦Δθ 50 The value satisfies / (p+q)≦0.500. The height p of the 0.1% area in the surface convex direction is the ratio Δθ 50 Other parameters (Δθ 50 and q). The height p of 0.1% area in the convex direction of the surface may be, for example, 1 nm or more and 15 nm or less, 2 nm or more and 12 nm or less, or 3 nm or more and 10 nm or less. The height p of 0.1% area in the convex direction of the surface can be adjusted, for example, by changing the number of reciprocating runs in the surface treatment of the magnetic recording medium T1.

[0066] The height p of the 0.1% area in the surface convex direction is calculated as follows. First, a 12.7 mm wide magnetic recording medium T1 is cut into a 10 mm long piece to create a rectangular sample measuring 12.7 mm x 10 mm. Furthermore, identically shaped samples are created at two locations every 10 m, for a total of three samples. Three measurement areas on the protective layer side of each sample are observed using an atomic force microscope (AFM), and two-dimensional (2D) surface profile data is obtained for a total of nine measurement areas. The AFM measurement conditions are as follows: AFM: Digital Instruments Dimension 3100 microscope (with NanoscopeIV controller) Cantilever: NanoWorld NCH-10T Measurement area: 30 μm x 30 μm square area Resolution: 512×512 AFM probe scanning direction: MD (machine direction) direction (longitudinal direction) of magnetic tape Measurement mode: tapping mode Scan ratio: 1Hz

[0067] Next, the obtained 2D surface profile data surfacex,y The 2D surface profile data (nm) (x is an integer between 0 and 511, and y is an integer between 0 and 511) was subjected to the following filtering process. In the following, the 2D surface profile data after filtering is referred to as "F surface x,y " Flatten: 3rd order Planefit: 3rd order in MD direction only

[0068] Above F surface x,y Measurement data at each measurement point (x, y) in pAFM x,y , and the height direction sensitivity Sens.Zscan [nm / V] and the height direction measurement range Z Scale [V] are used to calculate the height of each measurement point AFM using the following formula. x,y Calculate [nm]. Note that "65536" in the formula below is the total number of measurement points (256 x 256 = 65536). AFM x,y [nm] = (pAFM x,y ×Sens.Zscan [nm / V]×Z Scale [V]) / 65536

[0069] In the magnetic recording medium of the present technology, the "height data of the protective layer side surface obtained using an atomic force microscope" (hereinafter also simply referred to as "height data of the protective layer side surface") is the height of each measurement point obtained by the above formula: x,y means.

[0070] Next, a bearing curve is created based on the height data of the protective layer side surface. Specifically, first, the height of each measurement point is calculated by the above formula. x,y Average (average height H a ) is calculated by the height of each measurement point. x,y From the value of a The height difference H d That is, the height difference H d is calculated by the following formula: Height difference H between each measurement point d [nm] = (height of each measurement point AFM x,y )-(average height H a)

[0071] Height difference H between each measurement point d are arranged as a one-dimensional array. The one-dimensional array is then sorted in descending order of values. The height difference H of the one-dimensional array after the sorting d is the Y coordinate value of each point that describes the bearing curve. In other words, the Y coordinate value of the bearing curve is the height difference H d In this specification, the height difference H d is called the height on the bearing curve.

[0072] The ratio of the data number (element number of the one-dimensional array) of the one-dimensional array after sorting in descending order to the total number of data (total number of measurement points) is the X coordinate value of each point that draws the bearing curve. In other words, the X coordinate value of the bearing curve can be calculated using the following formula. X coordinate value [%] = Data Number / Total number of data x 100

[0073] Finally, the obtained X and Y coordinate values ​​are plotted on the XY coordinate system to create a bearing curve. Figure 4 is a graph showing an example of a bearing curve. In the XY coordinate system, the X axis represents the area ratio, and the Y axis represents the height (specifically, the height difference H d ) The area ratio is calculated by multiplying the height (height difference H d The frequency was calculated in descending order of the number of points measured by AFM (65,536 points) and expressed as a percentage, with the total number of points measured by AFM (65,536 points) set at 100.

[0074] The height where the area ratio is 0.1% in the bearing curve is the "height p of 0.1% area in the convex direction of the surface." Specifically, the height p of 0.1% area in the convex direction of the surface is calculated by calculating the height (height difference H d ) is p [nm] or more. For example, if there is a point P on the bearing curve with an X coordinate of 0.1 (%) and a Y coordinate of 5 (nm), the height p of 0.1% of the surface convexity is 5 nm. This means that the height (height difference H d) is 5 nm or more.

[0075] The height p of the 0.1% area in the surface convex direction is an index for evaluating the tendency of height of the convex shapes (protrusions) present on the protective layer side surface of the magnetic recording medium T1. The protrusions present on the protective layer side surface of the magnetic recording medium T1 are considered to reflect the protrusions present on the surface of layers located below the protective layer P. Therefore, the height of the protrusions present on the protective layer side surface is considered to reflect the height of the protrusions present on the surface of the recording layer 1 located below the protective layer P. Therefore, the height p of the 0.1% area in the surface convex direction can be a parameter that reflects the tendency of height of the protrusions present on the surface of the recording layer 1. It is considered that the smaller the height p of the 0.1% area in the surface convex direction, the lower the overall tendency of the protrusions present on the surface of the recording layer 1.

[0076] (1-2-3) Average thickness of protective layer q

[0077] The average thickness q of the protective layer P is 0.360≦Δθ 50 / (p+q)≦0.545, and preferably 0.380≦Δθ 50 / (p+q)≦0.540, and more preferably 0.400≦Δθ 50 The average thickness q of the protective layer P is a value that satisfies the ratio Δθ 50 Other parameters (Δθ 50 The average thickness q of the protective layer may be, for example, 1 nm or more and 10 nm or less, 2 nm or more and 8 nm or less, or 3 nm or more and 6 nm or less.

[0078] The average thickness q of the protective layer P is determined as follows. The magnetic recording medium T1 housed in a cartridge is unwound, and three samples are cut out at three locations—10 m to 20 m, 30 m to 40 m, and 50 m to 60 m—from the outermost edge—to prepare three samples. Each sample is then thinned using a method such as FIB (Focused Ion Beam). When using the FIB method, a carbon film and a tungsten thin film are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below. The carbon film is formed on the protective layer side and back layer side surfaces of the magnetic recording medium T1 by vapor deposition, and the tungsten thin film is further formed on the protective layer side surface by vapor deposition or sputtering. For samples in which the protective layer P is made of carbon, forming a carbon film as a protective film in the pretreatment for observing the TEM image may make it impossible to distinguish between the protective layer P and the protective film. In this case, it is not necessary to form a carbon film as a protective film on the protective layer side surface of the sample. The thinning is performed along the length direction (longitudinal direction) of the magnetic recording medium T1, that is, the thinning forms a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic recording medium T1.

[0079] The cross section of each obtained thinned sample is observed under a transmission electron microscope (TEM) under the following conditions to obtain a TEM image. Note that the magnification and acceleration voltage may be adjusted appropriately depending on the type of device. Apparatus: TEM (Hitachi H9000NAR) Accelerating voltage: 300 kV Magnification: 100,000x

[0080] Next, using the TEM image of each obtained sliced ​​sample, the thickness of the protective layer P is measured at 10 positions aligned in the longitudinal direction of the magnetic recording medium T1 of each sliced ​​sample. The measured values ​​of each obtained sliced ​​sample (30 measured values ​​in total) are simply averaged (arithmetic mean) to obtain the average thickness q [nm] of the protective layer P. Note that the positions where this measurement is performed are selected randomly from the test piece.

[0081] (2) Explanation of each layer

[0082] Referring again to FIG. 3, each layer of the magnetic recording medium T1 will be described.

[0083] (recording layer)

[0084] The recording layer 1 is a layer containing magnetic crystal grains and can function as a layer for recording or reproducing signals using magnetism. The recording layer 1 can be a perpendicular magnetic recording layer in which the magnetic crystal grains are perpendicularly oriented. Furthermore, from the viewpoint of improving recording density, it is preferable that the recording layer 1 be a granular magnetic layer having a granular structure containing a Co-based alloy.

[0085] The recording layer 1 having a granular structure is composed of ferromagnetic crystal grains containing a Co-based alloy and non-magnetic grain boundaries (non-magnetic materials) that surround the ferromagnetic crystal grains. More specifically, the recording layer 1 having a granular structure is composed of columns (columnar crystals) containing a Co-based alloy and non-magnetic grain boundaries that surround the columns and physically and magnetically separate each column. Due to this granular structure, the recording layer 1 exhibits a structure in which each columnar magnetic crystal grain is magnetically separated.

[0086] Co-based alloys have a hexagonal close-packed (hcp) structure, and their c-axes can be oriented perpendicular to the film surface (thickness direction of the magnetic recording medium). The recording layer 1 has a hexagonal close-packed structure, which further enhances the orientation characteristics of the recording layer 1. The Co-based alloy is preferably a CoPtCr-based alloy containing at least Co, Cr, and Pt. The CoPtCr-based alloy is not particularly narrowly limited, and may further contain an additive element. Examples of the additive element include one or more elements selected from Ni, Ta, etc. Preferably, the recording layer 1 has a granular structure in which grains containing Co, Pt, and Cr are separated by oxides.

[0087] The non-magnetic grain boundaries surrounding the ferromagnetic crystal grains contain a non-magnetic metal material. Here, "metal" includes semi-metals. The non-magnetic metal material may be, for example, a non-magnetic oxide. The non-magnetic oxide may be at least one of a metal oxide and a metal nitride. From the viewpoint of maintaining the granular structure more stably, it is preferable to use a metal oxide.

[0088] In the magnetic recording medium T1, the recording layer 1 has an average atomic ratio (also referred to as average composition) represented by the following formula (I). Note that the following formula (I) does not indicate a specific crystal structure, but simply represents the average atomic ratio of elements. In other words, the following formula (I) represents a value obtained from the results of measuring the atomic ratio of elements. The recording layer 1 may also contain elements other than those represented by the following formula (I). In other words, the recording layer 1 may be any layer as long as it has the average atomic ratio represented by the following formula (I), and may also contain other elements (for example, impurities, components diffused from other layers, etc.). [Co (100-X-Y) Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the above formula (I), 10≦X≦25, 8≦Y≦16, 6≦Z≦11, and MO N indicates a metal oxide.)

[0089] If the above X is less than 10, it is difficult to obtain a high SNR. u V act / k B T becomes less than 80, and thermal stability decreases. If X exceeds 25, it is difficult to obtain a high SNR. If Y is less than 8, it is difficult to obtain a high SNR. If Y exceeds 16, it is difficult to obtain a high SNR, and K u V act / k B T becomes less than 80, resulting in reduced thermal stability. If Z is less than 6, it is difficult to obtain a high SNR. If Z exceeds 11, it is difficult to obtain a high SNR.

[0090] In the formula (I), X is preferably 12 or more, more preferably 14 or more, even more preferably 16 or more, and particularly preferably 18 or more. When X is in this range, K u V act / k B The value of T increases, improving thermal stability. X is preferably 23 or less. By setting X to 23 or less, the magnetic recording medium T1 can exhibit a higher SNR. The numerical range of X may be defined by any of the above upper limits and any of the above lower limits, and is preferably 12≦X≦23, more preferably 14≦X≦23, even more preferably 16≦X≦23, and particularly preferably 18≦X≦23.

[0091] In the formula (I), Y is preferably 10 or more. When Y is 10 or more, the magnetic recording medium T1 can exhibit a higher SNR. Y is preferably 14 or less, and more preferably 12 or less. When Y is in this range, K u V act / k B The value of T increases, and the thermal stability improves. The numerical range of Y may be defined by any of the above upper limits and any of the above lower limits, and is preferably 8≦Y≦14, more preferably 8≦X≦12, and even more preferably 10≦X≦12.

[0092] In the above formula (I), Z is preferably 7 or greater. When Z is 7 or greater, the magnetic recording medium T1 can exhibit a higher SNR. Z is preferably 10 or less, and more preferably 9 or less. When Z is within this numerical range, the magnetic recording medium T1 can exhibit a higher SNR. The numerical range of Z may be defined by any of the above upper limits and any of the above lower limits, and is preferably 6≦Z≦10, more preferably 6≦Z≦9, and even more preferably 7≦Z≦9.

[0093] The metal oxide suitable for the non-magnetic grain boundary, i.e., MO in the above formula (I), NExamples of the oxides include metal oxides containing at least one element selected from Si, Cr, Cr, Al, Ti, Ta, Zr, Ce, Y, B, and Hf. Specific examples include SiO2, Cr2O3, CuO, Al2O3, TiO2, Ta2O5, and ZrO 2、 Examples of the metal oxide include B2O3 and HfO2. The metal oxide preferably includes one, two, or three selected from B2O3, SiO2, and TiO2, more preferably at least one selected from B2O3, SiO2, and TiO2, and even more preferably B2O3.

[0094] Examples of the metal nitride suitable for the non-magnetic grain boundary include metal nitrides containing at least one element selected from the group consisting of Si, Cr, Co, Al, Ti, Ta, Zr, Ce, Y, and Hf, etc. Specific examples include SiN, TiN, and AlN.

[0095] The reason why it is considered preferable that the metal oxide is B2O3 is explained below. As mentioned above, the role of the non-magnetic grain boundaries in the granular structure is to reduce the effect of exchange interactions acting between ferromagnetic crystal grains by separating the columns of Co-based alloy, i.e., by spatially separating the ferromagnetic crystal grains. The process by which the sputtered particles reach the base film and are precipitated has a significant effect on the state of this granular structure, and it has been revealed that a good granular structure is achieved when the melting point of the material that makes up the non-magnetic grain boundaries is lower than the melting point of the material that makes up the ferromagnetic crystal grains. For example, Co is used as the material for the ferromagnetic crystal grains. 80 Pt 20 If the non-magnetic grain boundary is SiO2 or TiO2, the melting points are 1600°C and 1843°C, respectively. 80 Pt 20 However, the melting point of B2O3 is 470℃, and 80 Pt 20The melting point of the nonmagnetic grain boundary material is significantly lower than that of the ferromagnetic crystal grains. When the melting point of the nonmagnetic grain boundary material is lower than that of the ferromagnetic crystal grains, the ferromagnetic crystal grains precipitate first at the tip of the underlayer column. After cooling progresses and the temperature drops, the nonmagnetic grain boundary material precipitates between the ferromagnetic grains, resulting in a good granular structure. For this reason, B2O3 is considered to be an ideal oxide for the recording layer (Reference: K.K. Tham, R. Kushibiki, S. Hinata, and S. Saito, "B2O3: Grain boundary material for high-Ku CoPt-oxide granular media with low degree of intergranular exchange coupling," Jpn. J. Appl. Phys., vol. 55, p. 07MC06, June 2016).

[0096] For the reasons described above, in the present technology, the recording layer 1 may preferably have a granular structure composed of magnetic crystal grains (particularly columnar magnetic crystal grains) and nonmagnetic grain boundaries surrounding the magnetic crystal grains. The melting point of the material forming the nonmagnetic grain boundaries is preferably lower than the melting point of the material forming the magnetic crystal grains, for example, by 100°C or more, more preferably by 300°C or more, and even more preferably by 500°C or more, 600°C or more, or 700°C or more. The difference between the former melting point and the latter melting point may be, for example, 1200°C or less, 1100°C or less, or 1000°C or less. In other words, the melting point of the material forming the nonmagnetic grain boundaries may preferably be, for example, 100°C to 1200°C lower, more preferably 300°C to 1100°C lower, and even more preferably 500°C to 1000°C lower than the melting point of the material forming the magnetic crystal grains.

[0097] The average atomic ratio of the recording layer 1 is determined as follows. First, the magnetic recording medium T1 housed in a cartridge is unwound, and pieces of the required size are cut out from three positions: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from one end of the outermost circumference, to prepare three samples. Next, the back layer on the back surface of each sample (the surface on the back layer 5 side) is removed using methyl ethyl ketone to obtain three specimens. The back surface of each sample (the surface from which the back layer 5 has been removed) is subjected to FIB (Focused Ion Beam) processing to remove the base layer 6, second seed layer 42, first seed layer 41, second underlayer 32, and first underlayer 31. This results in three analysis specimens, each containing only the recording layer 1, CAP layer C, protective layer P, and lubricant layer L. For each analysis sample, five locations within the metal column and five locations at the boundary between the metal column and the oxide are observed using a TEM, and the sample is analyzed by energy dispersive X-ray spectroscopy (EDX) to identify the average atomic ratio of each element contained in the recording layer 1. The measurement conditions for the TEM and elemental analyzer, as well as a more detailed procedure for identifying the average atomic ratio, are described below.

[0098] (TEM measurement conditions) Scanning transmission electron microscope: JEOL JEM-ARM200F Accelerating voltage: 200 kV Beam diameter: approx. 0.2 nmΦ Magnification: 2 million times (Measurement conditions for elemental analyzer) Elemental analyzer: JEOL JED-2300T X-ray detector: Si drift detector Energy resolution: approx. 140 eV X-ray extraction angle: 21.9° Solid angle: 0.98sr

[0099] (Procedure for identifying average atomic ratio) (1) Ratio of Co, Pt, and Cr Using a TEM image of the cross section of the recording layer 1 of the above analytical sample, EDX analysis is performed at five locations in the metal column to identify the average atomic ratios of Co, Pt, and Cr, thereby obtaining the values ​​of X and Y in the above formula (I). (2) Qualitative of M Using a TEM image of the cross section of the recording layer 1 of the above analytical sample, a qualitative analysis of M in the above formula (I) is carried out by EDX at five locations on the boundaries between the metal column and the oxide. (3) Metal to oxide ratio The area ratio of metal columns (black areas) to oxides (white areas) in a planar TEM image (a field of view containing 100 or more columns) is calculated using image analysis software "ImageJ" (available from the National Institutes of Health). The volume ratio of oxides is calculated from this area ratio. The element ratio of oxides to metals is calculated from this volume ratio. This gives the value of Z in the above formula (I). Details of the above processing using ImageJ are given below. (Measuring process of black area by binarization) The following processing is performed using ImageJ. In this processing, the image processing area is set to 80 nm x 80 nm. The specific operating procedures for the software are shown in parentheses for each step below. Step 1: Open the image file. (File → Open) Step 2: Enter the dimensions. (Analyze → Set Scale) The dimensions are set as follows: Distance in pixels: 640 Known distance: 64 Pixel aspect ratio: 1.0 Unit of length: um Step 3: Change the image type to 8-bit grayscale (Image menu > Type > 8bit). Step 4: Remove noise (Process > Smooth) Step 5: Binarize (Process > Binary > Make Binary) Step 6: Analyze. (Analyze menu → Analyze Particles) In this analysis, the threshold is set as follows: Size (Pixel^2): 100-10000 Circularity: 0.00-1.00 Show : Masks After setting the threshold, checking Summarize will display the Summary screen, which displays the Count (number of particles), Total Area (total area), Average size (number of particles), Area Function (percentage of area occupied by particles), and Mean (average). Step 7: For the images of five locations in the analysis sample, the above steps 1 to 6 are performed, and the average (simple average) of the obtained area functions (ratio of the area occupied by particles) is calculated. These average values ​​correspond to the area ratio of the metal element ((100-Z) in the above formula (I)).

[0100] When identifying the average atomic ratio, it is assumed that cross sections with the same area ratio overlap in the depth direction, and the area ratio = volume ratio. In addition, the oxide specific gravity and metal specific gravity used to calculate the element ratio from the volume ratio are the bulk values ​​of each element.

[0101] Average thickness of recording layer 1 t m is preferably 10 nm or more and 20 nm or less, more preferably 11 nm or more and 19 nm or less, and even more preferably 12 nm or more and 18 nm or less.

[0102] Average thickness of recording layer 1 t m is determined in the same manner as the average thickness of the protective layer P. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the recording layer 1.

[0103] (CAP layer)

[0104] The CAP layer C is a layer containing a material with strong magnetic interaction. A stacked structure consisting of the recording layer 1 having a granular structure and the CAP layer C is generally called Coupled Granular Continuous (CGC).

[0105] The CAP layer C may contain a CoPtCr-based material. Examples of the CoPtCr-based material include CoPtCr material, CoPtCrB material, and materials obtained by further adding a metal oxide to these materials (CoPtCr-metal oxide, CoPtCrB-metal oxide). The metal oxide added to the material (for example, MO in the following formula (2)) N ) can be, for example, at least one selected from the group consisting of Si, Ti, Mg, Ta, and Cr. Specific examples include SiO2, TiO2, MgO, Ta2O5, Cr2O3, and mixtures of two or more of these. The CAP layer C preferably contains a CoPtCrB material. That is, the CAP layer C is preferably a layer containing an alloy containing Co, Pt, Cr, and B.

[0106] The CAP layer C preferably has an average atomic ratio, for example, as shown in the following formula (1) or (2). Co 100-x-y-z Pt x Cr y B z ···(1) (However, in formula (1), x is 5≦x≦30, y is 5≦y≦20, and z is 0≦z≦15, preferably 10≦z≦30.) {[Co 100-x-y-z Pt x Cr y B z} 100-p -(MO N ) p ···(2) (In the formula (2), x is 5≦x≦30, y is 5≦y≦20, z is 0≦z≦15, preferably 5≦z≦12, and MO N is the metal oxide, and p is 5≦p≦15.

[0107] The average thickness of the CAP layer C is 4 nm or more, and preferably 5 nm or more. By making the average thickness of the CAP layer C 4 nm or more, the SNR can be increased and the saturation magnetic field (Hs) of the recording layer 1 can be reduced. The average thickness of the CAP layer C is preferably 10 nm or less. By making the average thickness of the CAP layer C 10 nm or less, a higher SNR can be obtained.

[0108] The average thickness of the CAP layer C is determined in the same manner as the average thickness of the protective layer P. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the CAP layer C.

[0109] (protective layer)

[0110] The protective layer P is a layer that serves to protect the recording layer 1 and the CAP layer C. The protective layer P contains, for example, a carbon material or silicon dioxide (SiO2). From the viewpoint of the film strength of the protective layer P, it is preferable that the protective layer P contains a carbon material. Examples of the carbon material include graphite, diamond-like carbon (abbreviated as DLC), and diamond.

[0111] (lubricant layer)

[0112] The magnetic recording medium T1 may have a lubricant layer L on top of the protective layer P. The lubricant layer L is a layer containing a lubricant, and its main role is to reduce friction of the magnetic recording medium T1 during running.

[0113] The lubricant layer L contains at least one type of lubricant. The lubricant layer L may further contain various additives, such as a rust inhibitor, as necessary. The lubricant has at least two carboxyl groups and one ester bond and contains at least one type of carboxylic acid compound represented by the following general chemical formula (1). The lubricant may further contain a type of lubricant other than the carboxylic acid compound represented by the following general chemical formula (1).

[0114] [ka] (In the above general chemical formula (1), Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group, Es is an ester bond, and R is an unsubstituted or substituted, saturated or unsaturated hydrocarbon group, although it may be absent.)

[0115] The carboxylic acid compound is preferably one represented by the following general chemical formula (2) or (3).

[0116] [ka] (In the above general chemical formula (2), Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

[0117] [ka] (In the above general chemical formula (3), Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group or hydrocarbon group.)

[0118] The lubricant preferably contains one or both of the carboxylic acid compounds represented by the above general chemical formula (2) and general chemical formula (3).

[0119] When a lubricant containing a carboxylic acid compound represented by general chemical formula (1) is applied to the recording layer 1 or the protective layer P, a lubricating effect is exhibited due to the cohesive force between the hydrophobic fluorine-containing hydrocarbon groups or hydrocarbon groups Rf. When the Rf group is a fluorine-containing hydrocarbon group, it preferably has a total of 6 to 50 carbon atoms and a total of 4 to 20 carbon atoms in the fluorinated hydrocarbon group. The Rf group may be saturated or unsaturated, straight-chain, branched-chain, or cyclic, but is preferably saturated and straight-chain.

[0120] For example, when the Rf group is a hydrocarbon group, it is desirable that it is a group represented by the following general chemical formula (4).

[0121] [ka] (However, in general chemical formula (4), l is an integer selected from the range of 8 to 30, more preferably 12 to 20.)

[0122] Furthermore, when the Rf group is a fluorine-containing hydrocarbon group, it is preferably a group represented by the following general chemical formula (5).

[0123] [ka] (In the general chemical formula (5), m and n are integers selected from the following ranges, m=2 to 20, n=3 to 18, and more preferably m=4 to 13, n=3 to 10.)

[0124] The fluorohydrocarbon groups may be concentrated in one location as described above or dispersed as shown in the following general chemical formula (6), and may be -CF3 or -CF2-, or may be -CHF2 or -CHF-, etc.

[0125] [ka] (However, in the general chemical formula (6), n1+n2=n, m1+m2=m.)

[0126] The reason for limiting the number of carbon atoms in the general chemical formulas (4), (5), and (6) as above is that if the number of carbon atoms constituting the alkyl group or fluorine-containing alkyl group (l or the sum of m and n) is equal to or greater than the lower limit, the length becomes appropriate, the cohesive force between the hydrophobic groups is effectively exerted, good lubrication is achieved, and friction and wear resistance are improved. Furthermore, if the number of carbon atoms is equal to or less than the upper limit, the solubility of the lubricant composed of the carboxylic acid compound in the solvent is maintained good.

[0127] In particular, when the Rf group contains a fluorine atom, it is effective in reducing the friction coefficient and further improving running performance. However, it is preferable to provide a hydrocarbon group between the fluorine-containing hydrocarbon group and the ester bond to separate the fluorine-containing hydrocarbon group and the ester bond, thereby ensuring the stability of the ester bond and preventing hydrolysis. The Rf group may also have a fluoroalkyl ether group or a perfluoropolyether group. The R group may not be present, but if present, it is preferable that the R group be a hydrocarbon chain with a relatively small number of carbon atoms. Furthermore, the Rf group or R group may contain elements such as nitrogen, oxygen, sulfur, phosphorus, and halogen as constituent elements, and may further have a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ester bond, etc. in addition to the functional groups described above.

[0128] Specifically, the carboxylic acid compound represented by the general chemical formula (1) is preferably at least one of the compounds shown below. That is, the lubricant preferably contains at least one of the compounds shown below. CF3(CF2)7(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)3(CH2) 10 COOCH(COOH)CH2COOH C 17 H 35 COOCH(COOH)CH2COOH CF3(CF2)7(CH2)2OCOCH2CH(C 18 H 37 )COOCH(COOH)CH2COOH CF3(CF2)7COOCH(COOH)CH2COOH CHF2(CF2)7COOCH(COOH)CH2COOH CF3(CF2)7(CH2)2OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2)6OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2) 11 OCOCH2CH(COOH)CH2COOH CF3(CF2)3(CH2)6OCOCH2CH(COOH)CH2COOH C 18 H 37 OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2)4COOCH(COOH)CH2COOH CF3(CF2)3(CH2)4COOCH(COOH)CH2COOH CF3(CF2)3(CH2)7COOCH(COOH)CH2COOH CF3(CF2)9(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)7(CH2) 12 COOCH(COOH)CH2COOH CF3(CF2)5(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)7CH(C9H 19 )CH2CH=CH(CH2)7COOCH(COOH)CH2COOH CF3(CF2)7CH(C6H 13 )(CH2)7COOCH(COOH)CH2COOH CH3(CH2)3(CH2CH2CH(CH2CH2(CF2)9CF3))2(CH2)7COOCH(COOH)CH2COOH

[0129] The carboxylic acid compound represented by the general chemical formula (1) is soluble in non-fluorinated solvents that have a low environmental impact, and has the advantage that it can be applied, immersed, sprayed, or otherwise treated with general-purpose solvents such as hydrocarbon solvents, ketone solvents, alcohol solvents, ester solvents, etc. Specific examples of such solvents include hexane, heptane, octane, decane, dodecane, benzene, toluene, xylene, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol, diethyl ether, tetrahydrofuran, dioxane, and cyclohexanone.

[0130] When the protective layer P contains a carbon material, applying the above-mentioned carboxylic acid compound as a lubricant onto the protective layer P causes two carboxyl groups and at least one ester bond group, which are the polar bases of the lubricant molecule, to be adsorbed onto the protective layer P, and the cohesive force between the hydrophobic groups allows the formation of a lubricant layer L with particularly good durability.

[0131] The lubricant may not only be retained as a lubricant layer L on the surface of the magnetic recording tape T as described above, but may also be contained and retained in layers such as the recording layer 1 and protective layer P that make up the magnetic recording medium T1.

[0132] (base layer)

[0133] In the magnetic recording medium T1, an underlayer 3 is provided directly under the recording layer 1. The underlayer 3 may have a two-layer structure consisting of a first underlayer 31 on the recording layer 1 side and a second underlayer 32 on the base layer 5 side.

[0134] The first underlayer 31 preferably contains ruthenium alone, a ruthenium alloy, or a Co-based alloy, more preferably contains ruthenium alone, and even more preferably consists of ruthenium alone. Ruthenium crystals have a hexagonal close-packed (hcp) structure. Using ruthenium, a ruthenium alloy, or a Co-based alloy for the first underlayer 31 improves lattice matching with the CoCrPt-based alloy contained in the recording layer 1. This improves the orientation characteristics of the recording layer 1.

[0135] The Co-based alloy preferably contains Cr and a metal oxide. The metal oxide contained in the Co-based alloy is preferably silicon dioxide (SiO2) or titanium dioxide (TiO2). More preferably, the Co-based alloy has an average atomic ratio represented by the following formula: [Co (100-y) Cr y ] (100-z) (MO2) z (However, y is within the range of 35≦y≦45, z is within the range of 10, and M is Si or Ti.)

[0136] In the above formula for the first underlayer 31, if z exceeds 10, the magnetic columnar crystals (columns) of the Co-based alloy and the non-magnetic grain boundaries that surround these columns and physically and magnetically separate each column will become excessive, resulting in a structure in which each columnar magnetic crystal grain is excessively magnetically separated, which is undesirable.

[0137] The average thickness of the first underlayer 31 is preferably 1 nm to 30 nm, more preferably 5 nm to 25 nm. When the first underlayer 31 contains ruthenium or a ruthenium alloy, the average thickness of the first underlayer 31 is even more preferably 10 nm to 20 nm, and particularly preferably 15 nm to 20 nm. When the first underlayer 31 contains a Co-based alloy, the average thickness of the first underlayer 31 is preferably 1 nm to 30 nm, more preferably 5 nm to 25 nm. The first underlayer 31 serves to make the columns of the recording layer 1 convex. A thicker average thickness of the first underlayer 31 is preferable to make the columns convex, but the thicker the average thickness, the worse the crystal orientation becomes. To balance the function of making the columns convex and the crystal orientation, it is preferable to keep the average thickness within the above numerical range. Furthermore, since the balance changes depending on the material forming the first underlayer 31, the preferred numerical range of the average thickness may vary depending on the material.

[0138] The second underlayer 32 provided directly under the first underlayer 31 preferably contains ruthenium alone, a ruthenium alloy, or a Co-based alloy, more preferably contains ruthenium alone, and even more preferably consists of ruthenium alone. Using ruthenium, a ruthenium alloy, or a Co-based alloy for the second underlayer 32 improves lattice matching with the CoCrPt-based alloy contained in the recording layer 1. This improves the orientation characteristics of the recording layer 1. When the first underlayer 31 contains ruthenium alone or a ruthenium alloy, the second underlayer 32 preferably contains ruthenium alone or a ruthenium alloy. When the first underlayer 31 contains a Co-based alloy, the second underlayer 32 preferably contains a Co-based alloy.

[0139] The Co-based alloy preferably has an average atomic ratio expressed by the following formula: Co (100-y) Cr y (However, the range is 35≦y≦45.)

[0140] The average thickness of the second underlayer 32 is preferably 1 nm to 50 nm, more preferably 5 nm to 50 nm. When the second underlayer 32 contains ruthenium or a ruthenium alloy, the average thickness of the second underlayer 32 is even more preferably 2 nm to 20 nm, particularly preferably 2 nm to 8 nm, or 3 nm to 7 nm. When the second underlayer 32 contains a Co-based alloy, the average thickness of the second underlayer 32 is even more preferably 10 nm to 50 nm, even more preferably 20 nm to 50 nm, and particularly preferably 25 nm to 45 nm. The second underlayer 32 serves to enhance crystal orientation. Depending on the material forming the second underlayer 32, the crystallographic alignment with the crystals constituting the layer directly below the second underlayer 32 (e.g., the NiW crystals of the first seed layer described below) may vary. Therefore, the average thickness preferable for enhancing crystal orientation may vary depending on the material forming the second underlayer 32.

[0141] The average thickness of the underlayer 3 is preferably 10 nm to 60 nm, more preferably 15 nm to 55 nm. When the seed layer 4 contains ruthenium or a ruthenium alloy, the average thickness of the underlayer 3 is even more preferably 15 nm to 40 nm, particularly preferably 20 nm to 40 nm, or 20 nm to 35 nm. When the underlayer 3 contains a Co-based alloy, the average thickness of the underlayer 3 is even more preferably 40 nm to 55 nm, particularly preferably 45 nm to 55 nm.

[0142] The average thickness of the underlayer 3 (first underlayer 31 and second underlayer 32) is determined in the same manner as the average thickness of the protective layer P. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the underlayer 3 (first underlayer 31 and second underlayer 32).

[0143] (seed layer)

[0144] The seed layer 4 is a layer located below the underlayer 3 and formed directly on one main surface of the base layer 5 (described later). According to one embodiment of the present technology, a first seed layer 41 may be provided directly below the underlayer 3, and a second seed layer 42 may be provided directly below the first seed layer 41. In other words, the seed layer 4 may have a two-layer structure consisting of the first seed layer 41 and the second seed layer 42.

[0145] From the viewpoint of ensuring a good SNR, the seed layer 4 is preferably provided when the intermediate layer 2 described below is formed thin, or even in a layer configuration without the intermediate layer 2. The seed layer 4 also serves to adhere the upper layers above the underlayer 3, i.e., the underlayer 3 (first underlayer 31 and second underlayer 32) and the recording layer 1, to the base layer 5.

[0146] The first seed layer 41 preferably contains a nickel-tungsten alloy, and more preferably is made of a nickel-tungsten alloy. The nickel-tungsten alloy may have an average atomic ratio represented by the following formula (7), for example. The first seed layer 41 is particularly preferably made of Ni 94It may be formed from W6. Ni (100-x) W x ···(7) (However, x is 1≦x≦10, preferably 2≦x≦10, more preferably 4≦x≦8, and even more preferably x=6.)

[0147] The second seed layer 42 preferably contains three atoms of Ti, Cr, and O, and may have a composition with an average atomic ratio expressed by the following formula (8): (TiCr) 98 It may be formed from O2. (TiCr) (100-x) O x ···(8) (However, x is 1≦x≦10, preferably 1≦x≦5, more preferably 1≦x≦3, and even more preferably x=2.)

[0148] In the above formula (8), if x is too large (for example, if it exceeds 10), TiO2 crystals will be generated in the seed layer, which is undesirable as it significantly reduces the function of the amorphous film.

[0149] Like Co-based alloys, Ti has a hexagonal close-packed (hcp) structure. When the seed layer 4 (particularly the second seed layer 42) contains Ti, the crystal structure of the seed layer 4 matches well with that of the recording layer 1, which also has a hexagonal close-packed (hcp) structure.

[0150] The seed layer 4 (particularly the second seed layer 42) containing the three atoms of Ti, Cr, and O improves the matching of the crystal structure between the recording layer 1, which also contains Cr, and the seed layer 4. When the underlayer 3 contains Cr, the seed layer 4 (particularly the second seed layer 42) containing the three atoms of Ti, Cr, and O also improves the matching of the crystal structure between the underlayer 3 and the seed layer 4.

[0151] The seed layer 4 contains oxygen because oxygen originating from or resulting from the film that constitutes the base layer 5, which will be described later, penetrates into the seed layer 4. In other words, the seed layer 4 of the magnetic recording medium T1 has a different atomic composition from the seed layer of a hard disk drive (HDD), which does not use a base layer 5 made of a film.

[0152] The average thickness of the first seed layer 41 is preferably 1.0 nm or more and 20.0 nm or less, more preferably 3.0 nm or more and 18.0 nm or less, and even more preferably 5.0 nm or more and 15.0 nm or less.

[0153] The average thickness of the second seed layer 42 is preferably 0.1 nm or more and 5.0 nm or less, more preferably 1.5 nm or more and 3.0 nm or less, even more preferably 1.7 nm or more and 3.0 nm or less, and particularly preferably 1.7 nm or more and 2.5 nm or less.

[0154] The average thickness of the seed layer 4 is preferably 1.1 nm or more and 25.0 nm or less, more preferably 5.0 nm or more and 20.0 nm or less, even more preferably 7.0 nm or more and 15.0 nm or less, and particularly preferably 10.0 nm or more and 15.0 nm or less.

[0155] The average thickness of the seed layer 4 (the first seed layer 41 and the second seed layer 42) is determined in the same manner as the average thickness of the protective layer P. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the seed layer 4 (the first seed layer 41 and the second seed layer 42).

[0156] (base layer)

[0157] The base layer 5 is a flexible, long, non-magnetic support that primarily functions as a layer that forms the foundation of the magnetic recording medium T1. The base layer 5 is sometimes called a base film layer or substrate, and is a film layer that imparts appropriate rigidity to the entire magnetic recording medium T1.

[0158] The average thickness of the base layer 5 is preferably 5.0 μm or less, 4.8 μm or less, 4.5 μm or less, more preferably 4.2 μm or less, even more preferably 3.6 μm or less, and even more preferably 3.3 μm or less. By having the average thickness of the base layer 5 within the above numerical range (e.g., 5.0 μm or less), the recording capacity that can be recorded in one data cartridge can be increased compared to that of general magnetic recording media. The lower limit of the average thickness of the base layer 5 may be determined from the film production limitations and the function of the base layer 5, but may be, for example, 2 μm or more, particularly 2.5 μm or more.

[0159] The average thickness of the base layer 5 can be determined as follows. First, the magnetic recording medium T1 housed in a cartridge is unwound and cut into 250 mm lengths from three locations: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from one end of the outermost circumference to prepare samples. Next, the layers other than the base layer 5 of each sample are removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Next, using a Mitutoyo laser hologram as a measuring device, the thickness of each sample (base layer 5) is measured at five locations, and the measured values ​​(15 locations in total) are simply averaged (arithmetic mean) to calculate the average thickness of the base layer 5. Note that the measurement locations are selected randomly from the sample.

[0160] The base layer 5 includes, for example, at least one of polyesters, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins. When the base layer 5 includes two or more of the above materials, the two or more materials may be mixed, copolymerized, or laminated. Examples of polyesters include, for example, at least one of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PCT (polycyclohexylene dimethylene terephthalate), PEB (polyethylene-p-oxybenzoate), and polyethylene bisphenoxycarboxylate. Examples of polyolefins include, for example, at least one of PE (polyethylene) and PP (polypropylene). Examples of cellulose derivatives include, for example, at least one of cellulose diacetate, cellulose triacetate, CAB (cellulose acetate butyrate), and CAP (cellulose acetate propionate). Examples of vinyl resins include at least one of PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride). Examples of other polymer resins include at least one of PA (polyamide, nylon), aromatic PA (aromatic polyamide, aramid), PI (polyimide), aromatic PI (aromatic polyimide), PAI (polyamideimide), aromatic PAI (aromatic polyamideimide), PBO (polybenzoxazole, such as Zylon (registered trademark)), polyether, PEK (polyetherketone), PEEK (polyetheretherketone), polyetherester, PES (polyethersulfone), PEI (polyetherimide), PSF (polysulfone), PPS (polyphenylene sulfide), PC (polycarbonate), PAR (polyarylate), and PU (polyurethane).

[0161] (Back layer)

[0162] The back layer 6 is formed on the main surface below the base layer 5. This back layer 6 plays a role in controlling friction that occurs when the magnetic recording medium T1 runs at high speed while facing a magnetic head, and in preventing winding disturbances, etc. In other words, it plays a fundamental role in ensuring stable running of the magnetic recording medium T1 at high speed.

[0163] The back layer 6 may contain a binder and non-magnetic powder. The back layer 6 may further contain at least one additive selected from the group consisting of a lubricant, a curing agent, and an antistatic agent, as necessary. The binder is preferably a resin having a structure in which a crosslinking reaction is imparted to a polyurethane resin or a vinyl chloride resin. However, the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required for the magnetic recording medium T1. The resin to be blended is not particularly limited, as long as it is a resin commonly used in coating-type magnetic recording media.

[0164] Examples of binders that can be contained in the back layer 6 include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-vinyl chloride-vinylidene chloride copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinyl chloride copolymer, methacrylic acid ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene-butadiene copolymer, polyester resin, amino resin, and synthetic rubber.

[0165] Furthermore, a thermosetting resin or a reactive resin may be used as the binder, and examples of such a resin include a phenolic resin, an epoxy resin, a urea resin, a melamine resin, an alkyd resin, a silicone resin, a polyamine resin, and a urea-formaldehyde resin.

[0166] Furthermore, to improve the dispersibility of the magnetic powder, polar functional groups such as -SO3M, -OSO3M, -COOM, and P=O(OM)2 may be introduced into each of the binders described above, where M is a hydrogen atom or an alkali metal such as lithium, potassium, or sodium.

[0167] The polar functional groups include -NR1R2, -NR1R2R3 + X - Side chain type with terminal group of >NR1R2 + X - In the formula, R1, R2, and R3 are hydrogen atoms or hydrocarbon groups, and X - is a halogen ion such as fluorine, chlorine, bromine, or iodine, or an inorganic or organic ion. Polar functional groups include —OH, —SH, —CN, and epoxy groups.

[0168] The non-magnetic powder contained in the back layer 6 may include, for example, at least one selected from inorganic particles and organic particles. One type of non-magnetic powder may be used alone, or two or more types of non-magnetic powder may be used in combination. The inorganic particles may include, for example, one or a combination of two or more selected from metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides. More specifically, the inorganic particles may be, for example, one or more selected from iron oxyhydroxide, hematite, titanium oxide, and carbon black. The shape of the non-magnetic F powder may be, for example, acicular, spherical, cubic, plate-like, or other shapes, but is not particularly limited to these.

[0169] The average particle size of the non-magnetic powder that can be contained in the back layer 6 is preferably 10 nm or more and 150 nm or less, and more preferably 15 nm or more and 110 nm or less. The non-magnetic powder may contain non-magnetic powder having two or more particle size distributions.

[0170] The curing agent may be, for example, a polyisocyanate, such as an aromatic polyisocyanate such as an adduct of tolylene diisocyanate (TDI) and an active hydrogen compound, or an aliphatic polyisocyanate such as an adduct of hexamethylene diisocyanate (HMDI) and an active hydrogen compound.

[0171] The lubricant that can be contained in the back layer 6 is the same as that in the lubricant layer L described above. That is, the explanation given for the lubricant that can be contained in the lubricant layer L also applies to the lubricant that can be contained in the back layer 6. Commercially available antistatic agents can be used as the antistatic agent that can be contained in the back layer 6, and adding an antistatic agent can prevent dirt and dust from adhering to the back layer 6.

[0172] The upper limit of the average thickness of the back layer 6 is preferably 0.6 μm or less. By keeping the upper limit of the average thickness of the back layer 6 at 0.6 μm or less, the running stability of the magnetic recording medium T1 in a recording and reproducing device can be maintained. The lower limit of the average thickness of the back layer 6 is not particularly limited, but is, for example, 0.2 μm or more. If it is less than 0.2 μm, there is a risk that the running stability of the magnetic recording medium T1 in a recording and reproducing device will be impaired.

[0173] The average thickness of the back layer 6 is determined as follows: First, the average thickness t T Measure the average thickness t [μm] of the magnetic recording medium T1. TThe method for measuring is as described below in this specification. Next, the back layer 6 of the sample is removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Thereafter, the thickness of the sample is measured again at five positions using the laser hologram, and these measurements are simply averaged (arithmetic mean) to obtain the average thickness t of the magnetic recording medium T1 from which the back layer 6 has been removed. B The measurement position is selected randomly from the sample. Then, the average thickness t of the back layer 6 is calculated by the following formula: b Calculate [μm]. t b [μm]=t T [μm]-t B [μm]

[0174] (3) Effects

[0175] The recording layer 1 of the magnetic recording medium T1 has the specific average atomic ratio described above. This allows the magnetic recording medium T1 to increase the SNR and achieve a K u V act / k B T can be 80 or more.

[0176] The magnetic recording medium T1 has a ratio Δθ 50 / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545. This allows the magnetic recording medium T1 to exhibit a high SNR.

[0177] The average thickness of the CAP layer C of the magnetic recording medium T1 is 4 nm or more, which allows the magnetic recording medium T1 to exhibit a high SNR and reduce the saturation magnetic field (Hs).

[0178] In the magnetic recording medium T1, the magnetic anisotropy energy K u , K. u V act / k B T and the saturation magnetic field (Hs) can be calculated as follows.

[0179] (Magnetic anisotropy energy K u )

[0180] After applying adhesive tape to the front and back of the magnetic recording medium T1 to reinforce it, the magnetic recording medium T1 is punched out with a φ6.39 mm punch to prepare a measurement sample. At this time, markings are made with any non-magnetic ink so that the longitudinal direction (running direction) of the magnetic recording medium T1 can be identified. Then, a magnetic anisotropy torque meter is used to measure the torque curve of the measurement sample (the entire magnetic recording medium T1) corresponding to the perpendicular direction (thickness direction) of the magnetic recording medium T1. A magnetic anisotropy torque meter "TRT-2" manufactured by Toei Kogyo Co., Ltd. is used to measure the torque curve. The measurement conditions are measurement mode: Torque-Angle, magnet rotation speed: 4 min. / 360. The same measurement is performed at applied magnetic fields of 10,000 Oe, 12,500 Oe, and 15,000 Oe. The parameters L2 (dyne-cm) and L4 (dyne-cm) obtained from this measurement are used to calculate the magnetic anisotropy energy constant Ku1 (erg / cm). 3 ) and Ku2(erg / cm 3 ) is calculated using the following formula, where r (mm) is the radius of the measurement sample and t is the average thickness (nm) of the recording layer. Ku1=A2-Ku2-2πMs 2 Ku2=2*A4 A2=L2 / (πr 2 *t)*10 9 A4=L4 / (πr 2 *t)*10 9

[0181] Ku1 (erg / cm) in each applied magnetic field 3 ) and Ku2(erg / cm 3 ) against (1 / applied magnetic field), and the values ​​obtained by extrapolation when the applied magnetic field is set to ∞ are used as Ku1' (erg / cm 3 ) and Ku2' (erg / cm 3 ) and the sum (Ku1' + Ku2') is the magnetic anisotropy energy K u (erg / cm 3 )

[0182] (K u Vact / k B T)

[0183] K u V act / k B T(K u : Magnetic anisotropy energy of magnetic powder, V act : activation volume of magnetic powder, k B : Boltzmann constant, T: absolute temperature) is calculated using the following Sherrock formula (References: IEEE TRANSACTIONS ON MAGNETICS, VOL. 50, NO. 11, NOVEMBER 2014, and J. Flanders and M.P. Sharrock: J. Appl. Phys., 62, 2918 (1987)). H r (t')=H0[1-{k B T / (K u V act )ln(f0t' / 0.693) n}] (However, H r :Residual magnetic force, t': Magnetization attenuation, H0: Magnetic field change, k B : Boltzmann constant, T: absolute temperature, K u : Magnetic anisotropy energy of magnetic powder, V act : activation volume of magnetic powder, f0: frequency factor, n: coefficient)

[0184] The frequency factor f0 is 5.0 x 10 9 Let be Hz. The coefficient n is set to a value according to the magnetocrystalline anisotropy of the magnetic material. If the magnetic material has uniaxial magnetocrystalline anisotropy and the magnetic tape is perpendicularly oriented, n is set to 0.5. On the other hand, if the magnetic material has multiaxial magnetocrystalline anisotropy (triaxial magnetocrystalline anisotropy), or if the magnetic material has uniaxial magnetocrystalline anisotropy but the magnetic tape is non-oriented, n is set to 0.77. The absolute temperature T is 298K. The value of H0 is the H r corresponding to the value of H when the effect of thermal disturbance is subtracted. r means the value of t' is Hr This means the time required for the average magnetization to become 0 due to thermal agitation of the magnetization when a magnetic field of the same magnitude as that of the magnetization is applied. The thermal stability evaluation requires the remanence at two different magnetic field change rates. The remanence curve at a magnetization change rate of 10 Oe / s was measured using a vibrating sample magnetometer (VSM) using an electromagnet. 8 Measurements at high magnetic field change rates in the Oe / s range are performed using a VSM with a pulsed magnetic field. r and Hr P Based on the measured values, t' is calculated using a phenomenological analytical formula and fitted to the Sherlock equation above, and H0 and K u V act / k B Find the value of T.

[0185] (Saturation magnetic field (Hs))

[0186] The saturation magnetic field (Hs) is determined as follows. First, the magnetic recording medium T1 contained in the cartridge is unwound, and three samples are cut out from each of three positions: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from one end of the outermost circumference. The three samples cut out from each position are stacked with double-sided tape so that the longitudinal direction of the magnetic recording medium T1 is the same, and then punched out with a φ6.39 mm punch to create a measurement sample for each sample cutting position. At this time, markings are made with any nonmagnetic ink so that the longitudinal direction (running direction) of the magnetic tape can be identified. Then, the MH loop of each measurement sample (the entire magnetic recording medium T1) corresponding to the perpendicular direction (thickness direction) of the magnetic recording medium T1 is measured using a VSM. Next, for each sample cut out from each of the above positions, the back layer is wiped off using acetone or ethanol, and then layers other than the back layer are wiped off using hydrochloric acid, leaving only the base layer 5. Then, after the front and back of the obtained base layer are reinforced with adhesive tape, it is punched out with a φ6.39 mm punch to make a sample for background correction (hereinafter simply referred to as "correction sample"). After that, for each of the correction samples cut out from each position, the MH loop of the correction sample (base layer) corresponding to the perpendicular direction of the base layer (perpendicular direction of the magnetic recording medium T1) is measured using VSM.

[0187] The MH loops of the measurement sample (the entire magnetic recording medium T1) and the correction sample (base layer) are measured using a Lakeshore vibrating sample magnetometer, Model 7400-0R. The measurement conditions are: measurement mode: full loop, maximum magnetic field: 15 kOe, magnetic field step: 500 Oe, time constant: 0.1 sec, and number of MH averages: 10.

[0188] After obtaining the MH loop of the measurement sample (the entire magnetic recording medium T1) and the MH loop of the correction sample (base layer), background correction is performed by subtracting the MH loop of the correction sample (base layer) from the MH loop of the measurement sample (the entire magnetic recording medium T1), and the background-corrected MH loop is obtained. This background correction calculation is performed using the measurement and analysis program included with the "7400-0R Model."

[0189] In the first quadrant of the obtained MH loop after background correction, a tangent is drawn to the coercive force (Hc), and the magnetic field strength at the point where this tangent intersects with the saturation magnetic field is taken as the saturation magnetic field (Hs). The above measurement and analysis program is used to calculate the coercive force (Hc). All of the above MH loop measurements are performed at 25°C. Furthermore, no "demagnetizing field correction" is performed when measuring the MH loop in the perpendicular direction to the magnetic recording medium T1.

[0190] 3. Second embodiment

[0191] (1) Structure of magnetic recording medium

[0192] The configuration of a magnetic recording medium T2 according to the second embodiment will be described with reference to FIG. 5. The magnetic recording medium T2 is, for example, a magnetic recording medium for perpendicular magnetic recording. The magnetic recording medium T2 has an intermediate layer 2 between the recording layer 1 and underlayer 3 described in 2 above (more specifically, between the recording layer 1 and the first underlayer 31). Specifically, in the magnetic recording medium T2, a second seed layer 42 and a first seed layer 41 are provided in this order on one major surface of a long base layer 5. The second underlayer 32 and the first underlayer 31 are provided in this order on the first seed layer 41. The intermediate layer 2 is provided on the first underlayer 31. The recording layer 1, which functions as a magnetic recording layer, is provided on the intermediate layer 2. The CAP layer C, the protective layer P, and the lubricant layer L are provided in this order on the recording layer 1. A back layer 6 is provided on the other major surface of the base layer 5. The configuration of the magnetic recording medium T2 is as explained in 2.(1) above, except that it has an intermediate layer 2, and this explanation also applies to this embodiment.

[0193] (2) Explanation of each layer

[0194] The lubricant layer L, protective layer P, CAP layer C, recording layer 1, underlayer 3 (first underlayer 31 and second underlayer 32), seed layer 4 (first seed layer 41 and second seed layer 42), base layer 5, and back layer 6 are as described above in 2.(2), and this description also applies to this embodiment.

[0195] (middle class)

[0196] The intermediate layer 2 is a layer that mainly plays a role in enhancing the orientation characteristics (granularity) of the recording layer 1 formed directly on the intermediate layer 2. The intermediate layer 2 preferably has a crystalline structure similar to that of the main component of the recording layer 1 that is in contact with the intermediate layer 2. For example, the intermediate layer 2 preferably contains a material that has a hexagonal close-packed structure similar to that of a Co-based alloy, with the c-axis of this structure oriented perpendicular to the film surface (thickness direction of the magnetic recording tape). This further enhances the crystalline orientation characteristics of the recording layer 1 and enables relatively good matching of the lattice constants between the intermediate layer 2 and the recording layer 1.

[0197] The hexagonal close-packed material used for the intermediate layer 2 preferably contains ruthenium. The intermediate layer 2 preferably contains Ru (ruthenium) alone or an alloy thereof. The intermediate layer 2 is more preferably formed from ruthenium alone or a ruthenium alloy. The ruthenium alloy may be, for example, a Ru alloy oxide such as RuCoCr(TiO2), Ru-SiO2, RuTiO2, or Ru-ZrO2. The ruthenium alloy may preferably have an average atomic ratio represented by the following formula: [Ru x Co y Cr 100-x-y ] 100-z (MO2) z (wherein x is 10≦x≦40, and preferably 15≦x≦35, y is 20≦y≦50, and preferably 25≦y≦45, z is 1≦z≦30, and more preferably 5≦z≦25, and M is Ti or Si.)

[0198] Ru is a rare metal, and from the viewpoint of cost, it is preferable to make the intermediate layer 2 as thin as possible, preferably 6.0 nm or less, more preferably 5.0 nm or less, and even more preferably 2.0 nm or less. Alternatively, from the viewpoint of cost, it is more preferable to completely eliminate the intermediate layer 2 (for example, the configuration of the first embodiment).

[0199] In the second embodiment, by providing an underlayer 4 and a seed layer 3 on top of the base layer 5, it is possible to obtain a magnetic recording medium with a good SNR even if the thickness of the intermediate layer 2 is reduced or even if a layer configuration without an intermediate layer 2 is used (for example, the first embodiment).

[0200] Furthermore, by utilizing the "wettability" of the intermediate layer 2, the material constituting the recording layer 1 formed by vacuum deposition on the intermediate layer 2 can diffuse more easily during crystallization, thereby increasing the column size of the crystals. For example, to ensure that the intermediate layer 2 containing Ru exhibits wettability, it must have a thickness of at least 0.5 nm.

[0201] 4. Third Embodiment

[0202] (1) Structure of magnetic recording medium

[0203] The configuration of a magnetic recording medium T3 according to the third embodiment will be described with reference to FIG. 6. The magnetic recording medium T3 is, for example, a magnetic recording medium for perpendicular magnetic recording. The magnetic recording medium T3 has a soft magnetic underlayer (SUL) 7 between the seed layer 4 and the base layer 5 (more specifically, between the second seed layer 42 and the base layer 5). More specifically, in the magnetic recording medium T3, the SUL 7 is provided on one major surface of the elongated base layer 5. A second seed layer 42 and a first seed layer 41 are provided on the SUL 7 in this order. A second underlayer 32 and a first underlayer 31 are provided on the first seed layer 41 in this order. A recording layer 1 functioning as a magnetic recording layer is provided on the first underlayer 31. A CAP layer C, a protective layer P, and a lubricant layer L are provided on the recording layer 1 in this order. A back layer 6 is provided on the other major surface of the base layer 5. The configuration of the magnetic recording medium T3 is as explained in 2.(1) above, except that it has an SUL, and this explanation also applies to this embodiment.

[0204] (2) Explanation of each layer

[0205] The lubricant layer L, protective layer P, CAP layer C, recording layer 1, underlayer 3 (first underlayer 31 and second underlayer 32), seed layer 4 (first seed layer 41 and second seed layer 42), base layer 5, and back layer 6 are as described above in 2.(2), and this description also applies to this embodiment.

[0206] (SUL)

[0207] The SUL7 shown in Figure 6 is a single-layer SUL. The SUL7 is a layer provided to efficiently draw leakage magnetic flux generated from the perpendicular magnetic head into the recording layer 1 when magnetic recording is performed on the recording layer 1. In other words, by providing the SUL7, the magnetic field strength from the magnetic head can be increased, making it possible to obtain a magnetic recording medium suitable for higher density recording. The magnetic recording medium T3 equipped with the SUL7 can also be called a "dual-layer perpendicular magnetic recording medium."

[0208] SUL7 includes an amorphous soft magnetic material. For example, it can be formed of a Co-based material, CoZrNb alloy, but other materials such as CoZrTa or CoZrTaNb can also be used. Alternatively, an Fe-based material such as FeCoB, FeCoZr, or FeCoTa can also be used. SUL7 may also be an antiparallel coupled SUL (APC-SUL), which has two soft magnetic layers sandwiching a thin interlayer and actively aligning the magnetizations antiparallel by utilizing exchange coupling via the interlayer.

[0209] The magnetic recording medium T3 may include an APC-SUL (Antiparallel Coupled SUL) instead of the single-layer SUL 7. The APC-SUL has two soft magnetic layers sandwiching a thin interlayer, and utilizes exchange coupling via the interlayer to actively make the magnetizations antiparallel.

[0210] 5. Manufacturing method of magnetic recording medium

[0211] The magnetic recording medium of the present technology can be manufactured, for example, as follows: First, a seed layer, an underlayer, a recording layer, a CAP layer, and a protective layer are sputter-deposited in this order on one main surface of a base layer. The atmosphere in the deposition chamber during sputtering is, for example, 1×10 -5 Pa~5×10 -5The thickness and properties (e.g., magnetic properties) of the seed layer, underlayer, recording layer, CAP layer, and protective layer can be controlled by adjusting the tape line speed for winding up the film that constitutes the base layer, the gas pressure (sputtering gas pressure) of Ar (argon) gas or the like introduced during sputtering, and the input power.

[0212] When the seed layer has multiple layers, they are deposited in order starting from the layer located on the bottom (i.e., the base layer side). For example, when the seed layer has a second seed layer and a first seed layer in order from the bottom, the second seed layer is deposited first, followed by the first seed layer. When the underlayer has multiple layers, they are deposited in order starting from the layer located on the bottom. For example, when the underlayer has a second underlayer and a first underlayer in order from the bottom, the second underlayer is deposited first, followed by the first underlayer.

[0213] When the magnetic recording medium of the present technology has an intermediate layer between the underlayer and the recording layer, the intermediate layer may be sputter-deposited as described above. In this case, the seed layer, underlayer, intermediate layer, recording layer, CAP layer, and protective layer are sputter-deposited in this order on one major surface of the base layer. When the magnetic recording medium of the present technology has an SUL between the base layer and the seed layer, the SUL may be sputter-deposited as described above. In this case, the SUL, seed layer, underlayer, recording layer, CAP layer, and protective layer are sputter-deposited in this order on one major surface of the base layer.

[0214] Next, a paint for the back layer is prepared by kneading and dispersing a binder, inorganic particles, a lubricant, etc. in a solvent, and the prepared paint is applied to the other main surface of the base layer and dried to form the back layer.

[0215] Next, a lubricant is applied onto the already formed protective layer to form a lubricant layer. As a method for applying the lubricant, various application methods such as gravure coating and dip coating can be used, and there is no particular limitation.

[0216] As a subsequent step, in order to adjust the warpage of the magnetic tape in the tape width direction, a hot roll treatment may be performed in which the raw roll is brought into contact with a metal roll having a surface temperature of about 150 to 230°C and made to run.

[0217] The wide magnetic recording medium obtained as described above is cut to a magnetic recording medium width that matches the specifications of the magnetic recording medium type (cutting process). For example, it is cut to a width of 1 / 2 inch (12.65 mm) and wound up on a predetermined roll. This allows for the production of a long magnetic recording medium with the desired magnetic recording medium width. Necessary inspections may be carried out during this cutting process.

[0218] Next, the magnetic recording medium cut to a predetermined width is cut to a predetermined length according to the type of product, and is formed into a magnetic recording cartridge. Specifically, the magnetic recording medium of a predetermined length is wound around a reel provided in a cartridge case and housed therein.

[0219] The magnetic recording medium undergoes a final product inspection process before being packaged and shipped. In the inspection process, pre-shipment inspections are carried out on, for example, electromagnetic conversion characteristics, running durability, etc., to confirm the final quality of the magnetic recording medium.

[0220] 6. Recording and playback equipment

[0221] (Configuration of recording / playback device)

[0222] Next, an example of the configuration of a recording and reproducing device 80 that performs recording and reproducing on the magnetic recording medium T of the present technology will be described with reference to Fig. 7. Note that the recording and reproducing device that performs recording and reproducing on the magnetic recording medium T of the present technology is not limited to one having the configuration described below.

[0223] The recording / reproducing device 80 has a configuration that allows adjustment of the tension applied to the magnetic recording medium T in the longitudinal direction. The recording / reproducing device 80 also has a configuration that allows a magnetic recording cartridge 10A to be loaded. Here, for ease of explanation, a case will be described in which the recording / reproducing device 80 has a configuration that allows one magnetic recording cartridge 10A to be loaded, but the recording / reproducing device 80 may also have a configuration that allows multiple magnetic recording cartridges 10A to be loaded.

[0224] The recording / reproducing device 80 is connected to information processing devices such as a server 91 and a personal computer (hereinafter referred to as "PC") 92 via a network 93, and is configured to be able to record data supplied from these information processing devices onto the magnetic recording cartridge 10A. The shortest recording wavelength of the recording / reproducing device 80 is preferably 100 nm or less, more preferably 75 nm or less, even more preferably 60 nm or less, and particularly preferably 50 nm or less.

[0225] As shown in FIG. 7, the recording / playback device 80 includes a spindle 81, a reel 82 on the recording / playback device side, a spindle drive device 83, a reel drive device 84, multiple guide rollers 85, a head unit 86, a communication interface (hereinafter, I / F) 87, and a control device 88.

[0226] The spindle 81 is configured so that a magnetic recording cartridge 10A can be attached thereto. The magnetic recording cartridge 10A conforms to the LTO (Linear Tape Open) standard, and rotatably accommodates a single reel 10C around which a magnetic recording medium T is wound in a cartridge case 10B. A V-shaped servo pattern is pre-recorded as a servo signal on the magnetic recording medium T. The reel 82 is configured so that the leading end of the magnetic recording medium T pulled out from the magnetic recording cartridge 10A can be fixed.

[0227] The spindle drive device 83 is a device that rotates the spindle 81. The reel drive device 84 is a device that rotates the reel 82. When recording or reproducing data on the magnetic recording medium T, the spindle drive device 83 and the reel drive device 84 rotate the spindle 81 and the reel 82, thereby causing the magnetic recording medium T to run. The guide roller 85 is a roller that guides the running of the magnetic recording medium T.

[0228] The head unit 86 includes a plurality of recording heads for recording data signals on the magnetic recording medium T, a plurality of reproducing heads for reproducing the data signals recorded on the magnetic recording medium T, and a plurality of servo heads for reproducing the servo signals recorded on the magnetic recording medium T. As the recording heads, for example, ring-type heads can be used, but the type of recording head is not limited to this.

[0229] The communication I / F 87 is for communicating with information processing devices such as a server 91 and a PC 92 , and is connected to a network 93 .

[0230] The control device 88 controls the entire recording / reproducing device 80. For example, in response to a request from the information processing device, such as the server 91 or the PC 92, the control device 88 records a data signal supplied from the information processing device onto the magnetic recording medium T using the head unit 86. In addition, in response to a request from the information processing device, such as the server 91 or the PC 92, the control device 88 reproduces the data signal recorded on the magnetic recording medium T using the head unit 86 and supplies it to the information processing device.

[0231] (Operation of recording / playback device)

[0232] Next, the operation of the recording / reproducing device 80 having the above configuration will be described.

[0233] First, the magnetic recording cartridge 10A is loaded into the recording / reproducing device 80, the leading end of the magnetic recording medium T is pulled out and transported to the reel 82 via a plurality of guide rollers 85 and a head unit 86, and the leading end of the magnetic recording medium T is attached to the reel 82.

[0234] Next, when an operating unit (not shown) is operated, the spindle driving device 83 and the reel driving device 84 are driven under the control of the control device 88, and the spindle 81 and the reel 82 are rotated in the same direction so that the magnetic recording medium T runs from the reel 10C to the reel 82. As a result, the magnetic recording medium T is wound onto the reel 82, while the head unit 86 records information onto the magnetic recording medium T or reproduces information recorded on the magnetic recording medium T.

[0235] When the magnetic recording medium T is rewound onto the reel 10C, the spindle 81 and the reel 82 are rotated in the opposite direction to the above, causing the magnetic recording medium T to run from the reel 82 to the reel 10C. During this rewinding, the head unit 86 also records information onto the magnetic recording medium T or reproduces information recorded on the magnetic recording medium T.

[0236] 7. Magnetic Recording Cartridge

[0237] (Cartridge configuration)

[0238] The present technology also provides a magnetic recording cartridge (also referred to as a tape cartridge) including a magnetic recording medium according to the present technology. That is, the magnetic recording medium included in the magnetic recording cartridge is the magnetic recording medium of the present technology described above. Within the magnetic recording cartridge, the magnetic recording medium may be wound around a reel, for example. The magnetic recording cartridge may include, for example, a communication unit that communicates with a recording / reproducing device, a storage unit, and a control unit that stores information received from the recording / reproducing device via the communication unit in the storage unit, and reads information from the storage unit and transmits it to the recording / reproducing device via the communication unit in response to a request from the recording / reproducing device. The information may include adjustment information for adjusting the tension applied to the magnetic recording medium in the longitudinal direction.

[0239] An embodiment of a magnetic recording cartridge according to the present technology will be described with reference to Fig. 8. Specifically, a magnetic recording cartridge 10A including a magnetic recording medium T according to the present technology will be described.

[0240] 8 is an exploded perspective view showing an example of the configuration of a magnetic recording cartridge 10A. The magnetic recording cartridge 10A is a magnetic recording cartridge that complies with the LTO (Linear Tape-Open) standard, and includes a cartridge case 10B made up of a lower shell 212A and an upper shell 212B, a reel 10C around which a magnetic tape (a tape-like magnetic recording medium) T is wound, a reel lock 214 and a reel spring 215 for locking the rotation of the reel 10C, a spider 216 for unlocking the locked state of the reel 10C, a slide door 217 that straddles the lower shell 212A and the upper shell 212B and opens and closes a tape pull-out opening 212C provided in the cartridge case 10B, a door spring 218 that biases the slide door 217 to a closed position of the tape pull-out opening 212C, a write protect 219 for preventing accidental erasure, and a cartridge memory 211. The reel 10C is generally disk-shaped with an opening in the center, and is composed of a reel hub 213A and a flange 213B made of a hard material such as plastic. A leader pin 220 is provided at one end of the magnetic tape T.

[0241] The cartridge memory 211 is provided near one corner of the magnetic recording cartridge 10A. When the magnetic recording cartridge 10A is loaded into the recording / reproducing device 80, the cartridge memory 211 faces a reader / writer (not shown) of the recording / reproducing device 80. The cartridge memory 211 communicates with the recording / reproducing device 30, specifically the reader / writer (not shown), using a wireless communication standard that complies with the LTO standard.

[0242] (Cartridge memory configuration)

[0243] An example of the configuration of the cartridge memory 211 will be described with reference to FIG.

[0244] 9 is a block diagram showing an example of the configuration of the cartridge memory 211. The cartridge memory 211 includes an antenna coil (communication unit) 331 that communicates with a reader / writer (not shown) using a specified communication standard, a rectification / power circuit 332 that generates power by using induced electromotive force from radio waves received by the antenna coil 331 and rectifying it, a clock circuit 333 that generates a clock from the radio waves received by the antenna coil 331 using induced electromotive force, a detection / modulation circuit 334 that detects the radio waves received by the antenna coil 331 and modulates the signal to be transmitted by the antenna coil 331, a controller (control unit) 335 that is composed of logic circuits and the like for identifying and processing commands and data from the digital signal extracted from the detection / modulation circuit 334, and a memory (storage unit) 336 that stores information. The cartridge memory 211 also includes a capacitor 337 connected in parallel to the antenna coil 331, and the antenna coil 331 and capacitor 337 form a resonant circuit.

[0245] The memory 336 stores information related to the magnetic recording cartridge 10A. The memory 336 is a non-volatile memory (NVM). The memory capacity of the memory 336 is preferably about 32 KB or more.

[0246] The memory 336 has a first storage area 336A and a second storage area 336B. The first storage area 336A is an area for storing information such as manufacturing information (e.g., a unique number of the magnetic recording cartridge 10A, etc.), usage history (e.g., the number of times the tape has been pulled out (Thread Count), etc.), etc.

[0247] The second memory area 336B is an area for storing additional information. Examples of additional information include, but are not limited to, tension adjustment information, management ledger data, index information, or thumbnail information of moving images stored on the magnetic tape T. The tension adjustment information includes the distance between adjacent servo bands (the distance between servo patterns recorded on adjacent servo bands) when data is recorded on the magnetic tape T. The distance between adjacent servo bands is an example of width-related information related to the width of the magnetic tape T. The distance between servo bands will be described in detail later. In the following description, the information stored in the first memory area 336A may be referred to as "first information," and the information stored in the second memory area 336B may be referred to as "second information."

[0248] The memory 336 may have multiple banks. In this case, some of the multiple banks may constitute a first memory area 336A, and the remaining banks may constitute a second memory area 336B. Specifically, for example, the memory 336 may have two banks, each with a memory capacity of approximately 16 KB, and one of the two banks may constitute the first memory area 336A, and the other bank may constitute the second memory area 336B.

[0249] The antenna coil 331 induces an induced voltage by electromagnetic induction. The controller 335 communicates with the recording / reproducing device 80 using a specified communication standard via the antenna coil 331. Specifically, for example, mutual authentication, sending and receiving of commands, or data exchange is performed.

[0250] The controller 335 stores information received from the recording / reproducing device 80 via the antenna coil 331 in the memory 336. In response to a request from the recording / reproducing device 80, the controller 335 reads information from the memory 336 and transmits it to the recording / reproducing device 80 via the antenna coil 331.

[0251] 8. Modified Magnetic Recording Cartridge

[0252] (Cartridge configuration)

[0253] In the above-described embodiment of the magnetic recording cartridge, the magnetic tape cartridge is described as a one-reel type cartridge, but the magnetic recording cartridge of the present technology may also be a two-reel type cartridge. That is, the magnetic recording cartridge of the present technology may have one or more (e.g., two) reels on which the magnetic tape is wound. Below, an example of a magnetic recording cartridge of the present technology having two reels will be described with reference to FIG. 10.

[0254] 10 is an exploded perspective view showing an example of the configuration of a two-reel type cartridge 421. Cartridge 421 includes an upper half 402 made of synthetic resin, a transparent window member 423 that fits into and is fixed to a window 402a opened in the top surface of upper half 402, a reel holder 422 that is fixed to the inside of upper half 402 and prevents reels 406 and 407 from floating up, a lower half 405 that corresponds to upper half 402, reels 406 and 407 that are stored in a space formed when upper half 402 and lower half 405 are combined, magnetic tape MT1 wound around reels 406 and 407, a front lid 409 that closes a front opening formed when upper half 402 and lower half 405 are combined, and a back lid 409A that protects magnetic tape MT1 exposed in this front opening.

[0255] The reel 406 includes a lower flange 406b having a cylindrical hub portion 406a in the center around which the magnetic tape MT1 is wound, an upper flange 406c having approximately the same size as the lower flange 406b, and a reel plate 411 sandwiched between the hub portion 406a and the upper flange 406c. The reel 407 has the same configuration as the reel 406.

[0256] The window member 423 is provided with mounting holes 423a at positions corresponding to the reels 406 and 407, respectively, for assembling reel holders 422, which are reel holding means for preventing these reels from floating up. The magnetic tape MT1 is the same as the magnetic tape T in the first embodiment.

[0257] 9. Working Example

[0258] Hereinafter, the present technology will be described in more detail with reference to examples, but the present technology is not limited to these examples. In the examples, the "average thickness" may also be simply referred to as "thickness."

[0259] Example 1 (Second seed layer formation process) First, under the following film-forming conditions, a (TiCr) was deposited on the surface of a long polymer film that forms a non-magnetic base layer. (100-x) O x (where x=2) was sputtered to form a seed layer having a thickness of 2 nm. Film deposition method: DC magnetron sputtering method Target: Ti 50 Cr 50 target Gas type: Ar Gas pressure: 0.5 Pa Input power: 21.5mW / mm 2 Feed speed: 4m / s

[0260] (First seed layer formation process) On the second seed layer, Ni 94 The first seed layer made of W6 was formed by sputtering to a thickness of 10.0 nm. Film deposition method: DC magnetron sputtering method Target: Ni 94 W6 Target Gas type: Ar Gas pressure: 0.3 Pa Input power: 47mW / mm 2 Feed speed: 4m / s

[0261] (Second underlayer deposition process) Next, a second underlayer made of Ru was formed on the first seed layer by sputtering under the following film formation conditions to a thickness of 5 nm. Film deposition method: DC magnetron sputtering method Target: Ru target Gas type: Ar Gas pressure: 0.3 Pa Input power: 24mW / mm 2 Feed speed: 4m / s

[0262] (First underlayer deposition process) Next, a first underlayer made of Ru was formed on the second underlayer by sputtering under the following film formation conditions to a thickness of 17 nm. Target: Ru target Gas type: Ar Gas pressure: 13Pa Input power: 90mW / mm 2 Feed speed: 4m / s

[0263] (Recording layer deposition process) Next, a (Co 72 Pt 18 Cr 10 ) 92. A recording layer made of -(B2O3)8 was deposited to a thickness of 14 nm. Film deposition method: DC magnetron sputtering method Target: (Co 80 Pt 10 Cr 10 ) 92 -(B2O3)8 target Gas type: Ar Gas pressure: 6Pa Input power: 90mW / mm 2 Feed speed: 4m / s

[0264] (CAP layer deposition process) Next, a Co film was formed on the recording layer under the following film forming conditions: 60 Pt 20 Cr 10 B 10 A 5 nm thick CAP layer consisting of Film deposition method: DC magnetron sputtering method Target: Co 60 Pt 20 Cr 10 B 10 target Gas type: Ar Gas pressure: 1.5Pa Input power: 13.5mW / mm 2 Feed speed: 4m / s

[0265] (Protective layer deposition process) Next, a protective layer made of carbon was formed on the recording layer by sputtering under the following film-forming conditions to a thickness of 5 nm. Film deposition method: DC magnetron sputtering method Target: Carbon target Gas type: Ar Gas pressure: 0.8Pa Input power: 90mW / mm 2 x3 Cathode Feed speed: 9m / s

[0266] (Lubricant layer formation process) Next, the prepared lubricant coating material was applied onto the protective layer to form a lubricant layer. The lubricant coating material was prepared by mixing 0.11% by mass of a perfluoroalkyl carboxylic acid ester and 0.06% by mass of a fluoroalkyldicarboxylic acid derivative in a general-purpose solvent.

[0267] (Back layer deposition process) Next, a coating material for forming a back layer was applied to the other main surface of the polymer film forming the base layer and dried to form a back layer. More specifically, a back layer was formed with a thickness of 0.3 μm, consisting of non-magnetic powder composed of carbon and calcium carbonate and a polyurethane binder. This resulted in a tape-shaped magnetic recording medium (magnetic recording tape).

[0268] (Surface treatment) The obtained magnetic recording tape was subjected to surface treatment by running it back and forth 500 times in an LTO8 drive at a tension of 1 N. The magnetic tape after the surface treatment was used as the magnetic recording tape of Example 1.

[0269] Example 2 The target for the recording layer is (Co 80 Pt 10 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0270] Example 3 The target for the recording layer is (Co 76 Pt 14 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0271] Example 4 The target for the recording layer is (Co 67 Pt 23 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0272] Example 5 The target for the recording layer is (Co 65 Pt 25 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0273] Example 6 The target for the recording layer is (Co 74 Pt 18 Cr8) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0274] Example 7 The target for the recording layer is (Co 70 Pt 18 Cr 12 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0275] Example 8 The target for the recording layer is (Co 66 Pt 18 Cr 16 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0276] Example 9 The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 94 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)6.

[0277] Example 10 The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 89 -(B2O3) 11 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed.

[0278] Example 11 The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 92A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(SiO2)8.

[0279] Example 12 The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(TiO2)8.

[0280] Example 13 The input power of the CAP layer was 10.8 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the thickness was changed to 4 nm.

[0281] Example 14 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that in the protective layer deposition process, the feed speed was changed to 7.5 m / min, the thickness of the protective layer was changed to 6 nm, and in the surface treatment, the tape was run back and forth 2000 times with a tension of 1 N using an LTO8 drive.

[0282] Example 15 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that in the protective layer deposition process, the feed speed was set to 15 m / min, the thickness of the protective layer was changed to 3 nm, and in the surface treatment, the tape was run back and forth 200 times with a tension of 1 N using an LTO8 drive.

[0283] Example 16 The input power for the second underlayer was 14.4 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the thickness was changed to 3 nm, and the surface treatment was performed by running the tape back and forth 200 times with a tension of 1 N in an LTO8 drive.

[0284] Example 17 The input power for the second underlayer was 9.6 mW / mm 2A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the thickness was changed to 2 nm and no surface treatment was performed.

[0285] Example 18 The input power for the second underlayer was 33.6 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1, except that the thickness was changed to 7 nm.

[0286] Example 19 Between the first underlayer and the recording layer, (Ru 25 Co 37.5 Cr 37.5 ) 86 -(TiO2) 14 The intermediate layer formed in the step 1 was deposited by sputtering to a thickness of 2 nm. Film deposition method: DC magnetron sputtering method Target: (Ru 25 Co 37.5 Cr 37.5 ) 86 -(TiO2) 14 target Gas type: Ar Gas pressure: 0.5 Pa Input power: 21.5mW / mm 2 Feed speed: 4m / s Other than the above, a magnetic recording tape was obtained in the same manner as in Example 1 above.

[0287] Example 20 The first underlayer is formed by (Co 60 Cr 40 ) 94 -(TiO2)6 was formed by sputtering to a thickness of 5 nm. Film deposition method: DC magnetron sputtering method Target: (Co 60 Cr 40 ) 94 -(TiO2)6 target Gas type: Ar Gas pressure: 7Pa Input power: 60mW / mm 2 Feed speed: 4 m / s The second underlayer is made of Co 60 Cr 40 The film was formed by sputtering to a thickness of 45 nm. Film deposition method: DC magnetron sputtering method Target: Co 60 Cr 40 target Gas type: Ar Gas pressure: 0.5 Pa Input power: 130mW / mm 2 Feed speed: 4m / s Other than the above, a magnetic recording tape was obtained in the same manner as in Example 1 above.

[0288] Example 21 The first underlayer is formed by (Co 60 Cr 40 ) 94 -(TiO2)6 was formed by sputtering to a thickness of 25 nm. Film deposition method: DC magnetron sputtering method Target: (Co 60 Cr 40 ) 94 -(TiO2)6 target Gas type: Ar Gas pressure: 7Pa Input power: 100mW / mm 2 Feed speed: 4m / s The second underlayer is made of Co 60 Cr 40 The film was formed by sputtering to a thickness of 25 nm. Film deposition method: DC magnetron sputtering method Target: Co 60 Cr 40 target Gas type: Ar Gas pressure: 0.5 Pa Input power: 100mW / mm 2 Feed speed: 4m / s Other than the above, a magnetic recording tape was obtained in the same manner as in Example 1 above.

[0289] Example 22 Between the base film and the second seed layer, Co 87 A soft magnetic underlayer (SUL) made of Zr5Nb8 was sputter-deposited to a thickness of 20.0 nm. Film deposition method: DC magnetron sputtering method Target: Co 87 Zr5Nb8 target Gas type: Ar Gas pressure: 0.5 Pa Input power: 95mW / mm 2 Feed speed: 4m / s Other than the above, a magnetic recording tape was obtained in the same manner as in Example 1 above.

[0290] (Comparative Example 1) The target for the recording layer is (Co 82 Pt8Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0291] (Comparative Example 2) The target for the recording layer is (Co 64 Pt 26 Cr 10 ) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0292] (Comparative Example 3) The target for the recording layer is (Co 75 Pt 18 Cr7) 92 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0293] Comparative Example 4 The target for the recording layer is (Co 65 Pt 18 Cr 17 ) 92A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)8.

[0294] (Comparative Example 5) The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 95 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed to -(B2O3)5.

[0295] (Comparative Example 6) The target for the recording layer is (Co 72 Pt 18 Cr 10 ) 88 -(B2O3) 12 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the target was changed.

[0296] (Comparative Example 7) The input power of the CAP layer was 8.1 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the thickness was changed to 3 nm.

[0297] (Comparative Example 8) A magnetic recording tape was obtained in the same manner as in Example 1 above, except that in the surface treatment, the tape was run back and forth 2000 times with a tension of 1 N in an LTO8 drive.

[0298] (Comparative Example 9) A magnetic recording tape was obtained in the same manner as in Example 1 above, except that in the protective layer deposition process, the feed speed was changed to 11.3 m / min, the thickness of the protective layer was changed to 4 nm, and in the surface treatment, the tape was run back and forth 2000 times with a tension of 1 N using an LTO8 drive.

[0299] (Comparative Example 10) A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the feed rate in the protective layer deposition step was changed to 5.6 m / min, the thickness of the protective layer was changed to 8 nm, and no surface treatment was performed.

[0300] (Comparative Example 11) A magnetic recording tape was obtained in the same manner as in Example 1 above, except that the feed rate in the protective layer deposition step was changed to 7.5 m / min, the thickness of the protective layer was changed to 6 nm, and no surface treatment was performed.

[0301] (Comparative Example 12) The input power for the second seed layer was 16.1 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1, except that the thickness was changed to 1.5 nm.

[0302] (Comparative Example 13) The input power for the second seed layer was 10.8 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1, except that the thickness was changed to 1.0 nm.

[0303] (Comparative Example 14) The input power for the second underlayer was 48 mW / mm 2 A magnetic recording tape was obtained in the same manner as in Example 1, except that the thickness was changed to 10 nm.

[0304] Evaluations were carried out for each of the magnetic recording tapes of Examples 1 to 22 and Comparative Examples 1 to 14. Specifically, for each of the magnetic recording tapes, the height p of 0.1% area in the convex direction of the surface, the saturation magnetic field (Hs), the magnetic anisotropy energy K u , K. u V act / k B T, half width Δθ 50 Furthermore, for each magnetic recording tape, the height p of 0.1% area in the convex direction of the surface, the average thickness q of the protective layer, and the half-value width Δθ 50 From the value of , the ratio Δθ 50 / (p+q) was calculated.

[0305] In this example, the average thickness of the protective layer, the average thickness of the CAP layer, the average thickness of the recording layer, the average thickness of the intermediate layer, the average thickness of the underlayer, the average thickness of the seed layer, the average thickness of the SUL, the height p of 0.1% area in the surface convex direction, the saturation magnetic field (Hs), and the magnetic anisotropy energy K u , K. u V act / k B T, and half-width Δθ 50 was determined by the measurement method explained in 2. In this evaluation, K u V act / k B A magnetic recording tape with a T of 80 or more was determined to have excellent thermal stability.

[0306] In this example, the average atomic ratio of the recording layer was determined by the measurement method described in 2 above. The average atomic ratio of the CAP layer was determined in the same manner as the average atomic ratio of the recording layer. The average atomic ratios of layers other than the recording layer were determined as follows. First, a 10 mm × 10 mm sample was cut out from the magnetic tape. While etching the sample from the film surface, depth direction analysis (depth profile measurement) of each layer was performed at three arbitrary locations using Auger Electron Spectroscopy (AES). Next, from the obtained depth profile, the average atomic ratios of Ru, Co, Cr, Ni, W, Ti, Cr, and O in the thickness direction were determined. The AES measurement conditions were as follows: Equipment name: ULVAC-PHI PHI-710 Measurement area: 10×20μm 2 Electronic acceleration: 5kV Etching rate: 1.3nm / min.

[0307] In this example, the BB-SNR (also simply referred to as SNR) was calculated as follows. First, a loop tester (manufactured by Microphysics) was used to obtain a playback signal from the magnetic tape. The conditions for obtaining the playback signal are shown below. Writer: Ring Type head Reader:TMR head Reader width: 800nm Speed: 1.5m / s Signal: Single recording frequency (400kfci) Recording current: Optimum recording current

[0308] The recording wavelength was set to 400 kFCI (kilo Flux Changes per Inch), and the SNR was calculated as the ratio of the voltage of the playback waveform to the voltage obtained by integrating the noise spectrum over the 0 kFCI to 1000 kFCI band. Error rate evaluation using the head used in this evaluation confirmed that a product-level error rate could be achieved with this head at an SNR of 10 dB. Therefore, a good SNR level was determined to be 10.0 dB or higher.

[0309] The evaluation results of each of the magnetic recording tapes of Examples 1 to 22 and Comparative Examples 1 to 14 are shown in Table 2 below.

[0310] [Table 2]

[0311] The results shown in Table 2 reveal the following:

[0312] All of the magnetic recording tapes of Examples 1 to 22 had an SNR of 10.0 dB or more, which was a high SNR. u V act / k B The T was 80 or more, indicating high thermal stability. These results demonstrate that the magnetic recording medium of the present technology exhibits a high SNR and is also excellent in thermal stability.

[0313] Comparing Examples 1 to 10 with Comparative Examples 1 to 6, it can be seen that in the above formula (I) showing the average atomic ratio of the recording layer, the conditions of 10≦X≦25, 8≦Y≦16, and 6≦Z≦11 contribute to a high SNR and excellent thermal stability. Specifically, it can be seen that the conditions of 10≦X and Y≦16 contribute to improvements in SNR and thermal stability, and that the conditions of X≦25, 8≦Y, and 6≦Z≦11 contribute to improvements in SNR.

[0314] Comparing Examples 1, 11, and 12, it is clear that even if the type of metal oxide contained in the recording layer is changed, a magnetic recording medium exhibiting a high SNR and excellent thermal stability can be obtained.

[0315] Comparing Examples 1 and 13 with Comparative Example 7, it can be seen that as the CAP layer becomes thicker, the SNR improves and the saturation magnetic field (Hs) decreases. It can also be seen that a CAP layer thickness of 4 nm or more contributes to the high SNR.

[0316] Comparing Examples 1, 14, and 15 with Comparative Examples 8 to 11, it was found that the ratio Δθ 50 It can be seen that adjusting / (p+q) affects the SNR. For example, 0.360≦Δθ 50 It can be seen that a high SNR can be obtained by satisfying / (p+q)≦0.540. It can also be seen that the height p of the 0.1% area in the convex direction of the surface can be adjusted by changing the number of round trips during surface treatment of the magnetic recording tape.

[0317] Comparing Examples 1, 16 to 18 and Comparative Example 14, the ratio Δθ 50 It can be seen that adjusting / (p+q) affects the SNR. For example, 0.360≦Δθ 50 It can be seen that a high SNR can be obtained by satisfying the condition of / (p+q)≦0.540. In addition, by increasing the input power when sputtering the second underlayer, the average thickness of the second underlayer can be increased, and by increasing the average thickness of the second underlayer, the half-width Δθ50 That is, by changing the average thickness of the underlayer (for example, the second underlayer), the half-value width Δθ 50 It is clear that it is possible to adjust

[0318] Comparing Examples 1 and 19, it is clear that even when an intermediate layer is provided between the underlayer (first underlayer) and the recording layer, a magnetic recording medium exhibiting a high SNR and excellent thermal stability can be obtained.

[0319] Comparing Examples 1, 20, and 21, it is clear that even if the materials for the first and second underlayers are changed, a magnetic recording medium exhibiting a high SNR and excellent thermal stability can be obtained.

[0320] Comparing Examples 1 and 22, it is clear that even when an SUL is provided between the base layer and the seed layer (second seed layer), a magnetic recording medium exhibiting a high SNR and excellent thermal stability can be obtained.

[0321] Comparing Example 1 with Comparative Examples 12 and 13, the half-value width Δθ 50 By changing the ratio Δθ 50 It can be seen that adjusting / (p+q) affects the SNR. In addition, by increasing the input power when sputtering the second seed layer, the average thickness of the second seed layer can be increased, and by increasing the average thickness of the second seed layer, the half-width Δθ 50 and the ratio Δθ 50 That is, by changing the average thickness of the seed layer (for example, the second seed layer), the half-width Δθ 50 and the ratio Δθ 50 It can be seen that / (p+q) can be adjusted.

[0322] The present technology can also be configured as follows. [1] The optical disc has a recording layer, a CAP layer, and a protective layer in this order, The recording layer has an average atomic ratio represented by the following formula: [Co (100-X-Y)Pt X Cr Y ] (100-Z) -(MO N ) Z (I) (In the formula (I), 10≦X≦25, 8≦Y≦16, and 6≦Z≦11; and MO N indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 and the ratio Δθ 50 / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The average thickness of the CAP layer is 4 nm or more. A tape-type magnetic recording medium. [2] the magnetic recording medium has a base layer, a seed layer, and an underlayer in this order; The magnetic recording medium according to [1], wherein the recording layer is provided on the underlayer. [3] the underlayer has a first underlayer and a second underlayer, The magnetic recording medium according to [2], wherein the recording layer is provided on the first underlayer. [4] the seed layer comprises a first seed layer and a second seed layer; The magnetic recording medium according to [2] or [3], wherein the underlayer is provided on the first seed layer. [5] the magnetic recording medium has an intermediate layer, The magnetic recording medium according to any one of [2] to [4], wherein the intermediate layer is provided between the underlayer and the recording layer. [6] the magnetic recording medium has an SUL, The magnetic recording medium according to any one of [2] to [5], wherein the SUL is provided between the base layer and the seed layer. [7] MO in the formula (I) N The magnetic recording medium according to any one of [1] to [6], wherein is at least one selected from B2O3, SiO2, and TiO2. [8] The magnetic recording medium according to any one of [1] to [7], wherein the CAP layer contains an alloy containing Co, Pt, Cr, and B. [9] The magnetic recording medium according to [2], wherein the underlayer contains ruthenium.

[10] The magnetic recording medium according to [4], wherein the first seed layer contains a nickel-tungsten alloy.

[11] The magnetic recording medium according to [4], wherein the second seed layer contains an alloy containing Ti, Cr, and O.

[12] The magnetic recording medium according to any one of [1] to

[11] , wherein the average thickness of the recording layer is 10 nm or more and 20 nm or less.

[13] The magnetic recording medium according to any one of [1] to

[12] , wherein the protective layer has an average thickness of 1 nm or more and 10 nm or less.

[14] The magnetic recording medium according to [3], wherein the average thickness of the first underlayer is 1 nm or more and 30 nm or less.

[15] The magnetic recording medium according to [3], wherein the average thickness of the second underlayer is 1 nm or more and 50 nm or less.

[16] The magnetic recording medium according to [4], wherein the average thickness of the first seed layer is 1.0 nm or more and 20.0 nm or less.

[17] The magnetic recording medium according to [4], wherein the average thickness of the second seed layer is 0.1 nm or more and 5.0 nm or less.

[18] The optical disc has a recording layer, a CAP layer, and a protective layer in this order, The recording layer has an average atomic ratio represented by the following formula: [Co (100-X-Y) Pt X CrY ] (100-Z) -(MO N ) Z (I) (In the formula (I), 10≦X≦25, 8≦Y≦16, and 6≦Z≦11; and MO N indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. 50 and the ratio Δθ 50 / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The CAP layer has an average thickness of 4 nm or more, and the magnetic recording medium is in the form of a tape. The magnetic recording medium is accommodated in a state of being wound around a reel. Magnetic recording cartridge. [Explanation of symbols]

[0323] 1 recording layer 2. Middle class 3 Base layer 31 1st base layer 32 Second base layer 4 Seed layer 41 First seed layer 42 Second seed layer 5 Base Layer 6 Back layer 7 Soft magnetic underlayer (SUL) 10A Magnetic recording cartridge 10B cartridge case 10C reel C CAP layer L Lubricant layer P protective layer T, T1, T2, T3 Tape-type magnetic recording media

Claims

1. a recording layer, a CAP layer, and a protective layer in this order; The recording layer has an average atomic ratio represented by the following formula: [Co （１００－Ｘ－Ｙ） Pt Ｘ Cr Ｙ ] （１００－Ｚ） -(MO Ｎ ) Ｚ ・・・(I) (In the formula (I), 10≦X≦25, 8≦Y≦16, 6≦Z≦11, and MO Ｎ indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. ５０ and the ratio Δθ ５０ / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The average thickness of the CAP layer is 4 nm or more. A tape-type magnetic recording medium.

2. the magnetic recording medium has a base layer, a seed layer, and an underlayer in this order; 2. The magnetic recording medium according to claim 1, wherein the recording layer is provided on the underlayer.

3. the underlayer includes a first underlayer and a second underlayer, 3. The magnetic recording medium according to claim 2, wherein the recording layer is provided on the first underlayer.

4. the seed layer includes a first seed layer and a second seed layer; The magnetic recording medium according to claim 2 , wherein the underlayer is provided on the first seed layer.

5. the magnetic recording medium has an intermediate layer, 3. The magnetic recording medium according to claim 2, wherein the intermediate layer is provided between the underlayer and the recording layer.

6. the magnetic recording medium has an SUL, The magnetic recording medium of claim 2 , wherein the SUL is disposed between the base layer and the seed layer.

7. MO in the formula (I) Ｎ But B ２ O ３ , SiO ２ , and TiO ２ 2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is at least one selected from the following:

8. The magnetic recording medium of claim 1 , wherein the CAP layer comprises an alloy containing Co, Pt, Cr, and B.

9. The magnetic recording medium of claim 2 , wherein the underlayer comprises ruthenium.

10. The magnetic recording medium of claim 4 , wherein the first seed layer comprises a nickel-tungsten alloy.

11. The magnetic recording medium of claim 4 , wherein the second seed layer comprises an alloy containing Ti, Cr, and O.

12. 2. The magnetic recording medium according to claim 1, wherein the average thickness of the recording layer is 10 nm or more and 20 nm or less.

13. 2. The magnetic recording medium according to claim 1, wherein the protective layer has an average thickness of 1 nm or more and 10 nm or less.

14. 4. The magnetic recording medium according to claim 3, wherein the average thickness of the first underlayer is 1 nm or more and 30 nm or less.

15. 4. The magnetic recording medium according to claim 3, wherein the average thickness of the second underlayer is 1 nm or more and 50 nm or less.

16. 5. The magnetic recording medium according to claim 4, wherein the first seed layer has an average thickness of 1.0 nm or more and 20.0 nm or less.

17. 5. The magnetic recording medium according to claim 4, wherein the second seed layer has an average thickness of 0.1 nm or more and 5.0 nm or less.

18. a recording layer, a CAP layer, and a protective layer in this order; The recording layer has an average atomic ratio represented by the following formula: [Co （１００－Ｘ－Ｙ） Pt Ｘ Cr Ｙ ] （１００－Ｚ） -(MO Ｎ ) Ｚ ・・・(I) (In the formula (I), 10≦X≦25, 8≦Y≦16, 6≦Z≦11, and MO Ｎ indicates a metal oxide.) The height p [nm] of the 0.1% area in the surface convex direction in a bearing curve created based on height data of the protective layer side surface obtained using an atomic force microscope, the average thickness q [nm] of the protective layer, and the half-width Δθ of the rocking curve of the CoPtCr hcp(0002) peak in X-ray diffraction in the out-of-plane direction of the recording layer. ５０ and the ratio Δθ ５０ / (p+q) is equal to or greater than 0.360 and equal to or less than 0.545, and The CAP layer has an average thickness of 4 nm or more, and the magnetic recording medium is in the form of a tape. The magnetic recording medium is accommodated in a state of being wound around a reel. Magnetic recording cartridge.

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