Magnetic recording medium, magnetic recording tape cartridge, and method for manufacturing magnetic recording medium

Abstract

The objective of the present technique is to provide a technique, regarding a magnetic recording medium, enabling adjustment to such a range that deterioration of a magnetic head can be suppressed while ensuing a cleaning force for removing dirt from the magnetic head during running of the magnetic recording medium. The present inventors have conducted intensive research to find that, by adding an H element to a protective layer containing DLC of a magnetic recording medium, it is possible to make an adjustment to such a range that deterioration of a magnetic head can be suppressed while ensuring a cleaning force for removing dirt from the magnetic head during running of the magnetic recording medium.

Description

Magnetic recording medium, magnetic recording tape cartridge, and method of manufacturing magnetic recording medium

[0001] This technology relates to a magnetic recording medium, a magnetic recording tape cartridge, and a method for manufacturing the magnetic recording medium. More specifically, it relates to a technology that can adjust the cleaning power to a range that can suppress deterioration of the magnetic head while ensuring the cleaning power that removes dirt from the magnetic head when the magnetic recording medium is running.

[0002] Conventionally, techniques relating to magnetic recording media having a protective layer have been known.

[0003] For example, Patent Document 1 below discloses that the protective layer of a magnetic recording medium can contain DLC.

[0004] WO2024 / 038825 publication

[0005] The main purpose of this technology is to provide a technology that can be adjusted to a range that suppresses deterioration of a magnetic head while ensuring cleaning power to remove dirt from the magnetic head when the magnetic recording medium is running.

[0006] As a result of extensive research, the inventors have discovered that by adding H element to the protective layer containing DLC ​​of a magnetic recording medium, it is possible to ensure the cleaning power to remove dirt from the magnetic head when the magnetic recording medium is running, while adjusting the range to suppress deterioration of the magnetic head.

[0007] That is, in this technology, a base layer, a magnetic layer containing magnetic crystal particles, and a protective layer are laminated in this order, and the protective layer contains DLC and H element. When the surface of the protective layer is measured by Raman spectroscopy, the wavelength of the light having a wavelength of 1000 to 1800 cm is ―１The present invention provides a magnetic recording medium, wherein the baseline of the relative intensity of the Raman spectrum in a measurement region is defined by a linear function, the relative intensity of the Raman spectrum derived from the H element is defined as a value obtained by integrating the baseline, and the relative ratio of the relative intensity of the Raman spectrum derived from the H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region exceeds 0.32. In the magnetic recording medium of the present technology, the relative ratio of the relative intensity of the Raman spectrum derived from the H element may be 0.38 or more. Furthermore, the relative ratio of the relative intensity of the Raman spectrum derived from the H element may be 0.53 or less, or may be less than 0.50. When secondary ion mass measurement is performed on the surface of the magnetic recording medium of the present technology on which the protective layer is provided using a Ga liquid metal ion gun, the counts per second of the elements constituting the magnetic crystal grains may be 243 cps or less. Furthermore, the elements constituting the magnetic crystal grains may be any one of Co, Pt, and Cr. The magnetic recording medium of the present technology may have a thickness of 4.50 μm or less. The protective layer of the magnetic recording medium of the present technology may have a thickness of 10.0 nm or less. The protective layer of the magnetic recording medium of the present technology may have one or more H-element-added layers in which the relative ratio of the relative intensities of the Raman spectra derived from the H element exceeds 0.32, and one or more H-element-unadded layers in which the relative ratio of the relative intensities of the Raman spectra derived from the H element does not exceed 0.32. In this case, the thickness of the H-element-added layer may be 3.0 nm or less. The magnetic recording medium of the present technology may have a lubricant layer containing a lubricant on the outside of the protective layer. The lubricant may contain a compound having a fluorine hydrocarbon group. In this case, the surface of the lubricant layer may be coated with a 3.0×10 ―６When measured by X-ray photoelectron spectroscopy at a setting of 6 kV / 20 mA at a pressure of 0.1 Pa or less, the counts per second of a peak corresponding to a fluorine 1s orbital may be 32 kcps or less. Furthermore, the counts per second of the peak corresponding to a fluorine 1s orbital may be 28 kcps or more. The magnetic recording medium of the present technology may have a seed layer between the substrate layer and the magnetic layer. Furthermore, the substrate layer may have a back layer on the surface opposite to the surface facing the magnetic layer. Furthermore, the present technology provides a magnetic recording tape cartridge configured such that a magnetic recording tape using the magnetic recording medium of the present technology is wound around a reel and housed in a case.

[0008] Next, the present technology provides a method for manufacturing a magnetic recording medium, which comprises forming a protective layer by sputtering carbon element on the surface of the magnetic layer side of a magnetic recording medium having a laminated structure with a base layer and a magnetic layer containing magnetic crystal grains, and performing the sputtering in an atmosphere of an inert gas to which a gas containing a compound containing H element has been added. In this case, the gas containing the compound containing H element may be a hydrocarbon gas, and the hydrocarbon gas may be ethylene.

[0009] 1 is a cross-sectional view showing an example of the configuration of a magnetic recording medium according to the present technology. 2 is a ternary phase diagram of carbon contained in a protective layer. 3 is a wave number of 1000 to 1800 cm ―１1 is a diagram showing a method for identifying the content of H element from the measurement results of the relative intensity of the Raman spectrum in a measurement region of a magnetic crystal grain. FIG. 1 is an image diagram of forming a protective layer by a conventional method. FIG. 1 is an image diagram of forming a protective layer using the present technology. FIG. 2 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 3 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 4 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 5 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 6 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 7 is a cross-sectional view showing a modified example of the configuration of the magnetic recording medium of the present technology. FIG. 8 is a diagram showing an example of the configuration of a magnetic recording tape cartridge that accommodates a magnetic recording tape using the magnetic recording medium of the present technology. FIG. 9 is a diagram showing an example of the configuration of a recording and reproducing device that uses the magnetic recording tape cartridge of the present technology. FIG. 10 is a diagram showing a schematic diagram of a vacuum sputtering device. FIG. 11 is an image diagram of a protective layer formed using the vacuum sputtering device. FIG. 12 is a graph showing a change in the number of counts per second of elements constituting magnetic crystal grains due to the addition of H element when secondary ion mass measurement is performed using a Ga liquid metal ion gun. FIG. 13 is a graph showing a change in the number of counts per second of elements constituting magnetic crystal grains when secondary ion mass measurement is performed using a Ga liquid metal ion gun, relative to the film thickness of the protective layer. FIG. 14 is a schematic diagram showing the configuration of a dedicated jig for abrasiveness measurement. 1 is a schematic diagram showing an abrasiveness bar, and FIG. 2 is a schematic diagram showing the amount of wear (abrasion) of the abrasiveness bar.

[0010] Preferred embodiments of the present technology will be described below. However, the embodiments shown below are examples of typical embodiments of the present technology, and the present technology is not limited to only the preferred embodiments below and can be freely modified within the scope of the present technology.

[0011] [Magnetic Recording Medium] The magnetic recording medium of the present technology has a base layer, a magnetic layer containing magnetic crystal particles, and a protective layer laminated in this order, and the protective layer contains DLC and element H. In the magnetic recording medium of the present technology, by adding element H to the protective layer containing DLC, it is possible to suppress deterioration of the magnetic head while ensuring cleaning power to remove dirt from the magnetic head when the magnetic recording medium is running.

[0012] In this specification, DLC (diamond-like carbon) refers to a compound having a region where carbon atoms constituting the DLC are bonded mainly by SP3 bonds. The DLC may also contain a region having graphite-like properties including SP2 bonds.

[0013] 1 is a cross-sectional view showing an example of the configuration of a magnetic recording medium according to the present technology. In this example, the magnetic recording medium T has a laminated structure of a substrate layer (base layer 5), a magnetic layer (recording layer 1), and a protective layer P, as well as a lubricant layer L on the side of the protective layer P opposite the substrate layer (the surface side of the magnetic recording medium T), an underlayer 3 (first underlayer 31 and second underlayer 32) between the magnetic layer 1 and the substrate layer 5, a seed layer 4 (first seed layer 41 and second seed layer 42), and a back layer 6 on the side of the substrate layer 5 opposite the magnetic layer 1 (the surface side of the magnetic recording medium T opposite the lubricant layer L).

[0014] Note that the configuration of the magnetic recording medium shown in FIG. 1 is one example, and magnetic recording media of any configuration can be designed by adding or omitting any layer depending on the intended use of the magnetic recording medium, as in the configurations of the modified examples described below.

[0015] The layers constituting the magnetic recording medium of the present technology can be formed by any method, such as sputtering, CVD (chemical vapor deposition), deposition, or coating. For example, each layer may be formed in order by sputtering on a member that serves as a base layer that functions as a support for the magnetic recording medium. Alternatively, the layers may be formed by combining any film formation methods.

[0016] Hereinafter, each of the layers that can constitute the magnetic recording medium will be specifically described.

[0017] <Protective Layer> The protective layer constituting the magnetic recording medium is a layer provided on the outer side of the magnetic layer (on the surface side of the magnetic recording medium) relative to the substrate layer, and serves to protect the magnetic layer. By providing the protective layer, the magnetic layer is physically protected and it is possible to prevent the magnetic layer from being exposed on the surface of the magnetic recording medium and from deteriorating due to rust or the like. Furthermore, when the magnetic recording medium has a CAP layer, which will be described later, the protective layer serves to protect the magnetic layer and the CAP layer.

[0018] From the viewpoint of film strength, the protective layer of the magnetic recording medium according to the present technology preferably contains a carbon element (carbon) such as diamond-like carbon (DLC). The carbon element may be in the form of graphite, diamond, or the like, in addition to DLC.

[0019] When a magnetic recording tape using a magnetic recording medium, such as LTO, is used in the same linear recording / reproducing device, information is recorded or reproduced while in contact with a magnetic head. Therefore, repeated running of the magnetic recording tape causes wear of the magnetic head, which can wear away the protective layer (overcoat layer / OC layer) of the magnetic head, resulting in head damage (deterioration of head resistance) of the magnetic head.

[0020] In particular, when a protective layer containing DLC ​​is formed by sputtering, the hardness can be higher than when the protective layer is formed by CVD or the like. This can provide a high abrasive power and can favorably maintain the function of removing dirt from the magnetic head caused by magnetic crystal particles, etc. However, as mentioned above, high hardness can sometimes lead to head damage to the magnetic head.

[0021] In light of the above, it is preferable to be able to adjust the tape polishing force within a range that can suppress deterioration of the magnetic head while ensuring the cleaning force that removes dirt from the magnetic head during magnetic recording medium running. That is, the present technology can adjust the hardness of the protective film by improving the film quality of the protective film, thereby achieving a suitable tape polishing force. More specifically, the film hardness of the protective layer containing DLC ​​can be suitably softened to achieve a suitable tape polishing force.

[0022] The abrasive power of the tape that can suppress deterioration of the magnetic head while ensuring the cleaning power to remove dirt from the magnetic head when the magnetic recording medium is running, as described above, may be specified, for example, using the wear volume shown below as an index.

[0023] (Wear Volume) A 30 m long magnetic recording tape was run repeatedly 1000 times around a square prism bar (abrasivity bar) made of a ceramic material (AlFeSi) at a wrap angle of 12° and a tension of 1.0 N±0.1 N, and the wear volume of the abrasivity bar was measured and calculated using the following formula (11).

[0024] Wear volume: V=d×(d / 2)×1 / 2×12700[μm 3 ]... (11)

[0025] The tape abrasive power that can ensure the cleaning power to remove dirt from the magnetic head while the magnetic recording medium is running is, for example, when the abrasion volume is 1.8E05 [μm 3 On the other hand, the polishing power of the tape is, for example, 2.8E06 [μm 3 If it is possible to adjust the magnetic head thickness to less than [0.01], deterioration of the magnetic head can be suitably suppressed.

[0026] In this technology, by adding H element to a protective layer containing DLC, the film hardness of the protective layer is suitably softened, thereby realizing a suitable tape polishing force.

[0027] More specifically, the improvement in the film quality of the protective film according to this technology will be described using the ternary phase diagram of carbon in Fig. 2. In the ternary phase diagram shown in Fig. 2, the top vertex represents the sp3 hybrid orbital, the bottom left vertex represents the sp2 hybrid orbital, and the bottom right vertex represents the H element.

[0028] In this ternary phase diagram, compounds exhibit diamond-like properties as they approach the top end. Specifically, they exhibit high hardness, transparency, and insulating properties. On the other hand, compounds exhibit graphite-like properties as they approach the bottom left end. Specifically, they are soft, black, and conductive. Furthermore, as they approach the right end, the content of H element in the compound increases, and they begin to take on polymer-like properties. Specifically, they become softer, smoother, and semi-transparent.

[0029] When DLC is formed by sputtering, the DLC formed is plotted in the shaded region of the ternary phase diagram in Figure 2 (Sputtered a-C:H in Figure 2). In this technology, for example, by adding H element to the protective layer, the DLC approaches the region at the bottom right of the ternary phase diagram. This suitably softens the film hardness of the protective layer, achieving a suitable tape polishing force.

[0030] The content of H element in the protective layer of the magnetic recording medium of the present technology can be determined by the relative intensity of the Raman spectrum derived from H element. The relative intensity of the Raman spectrum derived from H element is measured by Raman spectroscopy at a wave number of 1000 to 1800 cm. ―１ The baseline of the relative intensity of the Raman spectrum in the measurement region is defined by a linear function, and the value obtained by integrating this baseline is used as the reference.

[0031] FIG. 3 shows the relative intensity of the Raman spectrum measured by Raman spectroscopy at wave numbers of 1000 to 1800 cm ―１ 3 is an example of a graph of the measurement results in the measurement region of 1. In Fig. 3, the vertical axis indicates the relative intensity of the Raman spectrum, and the horizontal axis indicates the wave number.

[0032] 3, the baseline is defined by a linear function for the graph of the relative intensity of the Raman spectrum. The relative intensity of the Raman spectrum derived from the H element in the target protective layer can be calculated from the value obtained by integrating the baseline.

[0033] The graph of the relative intensity of the Raman spectrum in FIG. 3 shows the wave number of 1300 cm ―１ The D peak observed around 1550 cm is a peak derived from sp3 hybrid orbitals associated with diamond-like properties, and has a wave number of 1550 cm ―１ The G peak observed in the vicinity is a peak derived from sp2 hybrid orbitals associated with graphitic properties.

[0034] In this technology, by adding H element to the protective layer, ―１The relative ratio of the relative intensity of the Raman spectrum derived from the H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region can be adjusted to a range exceeding 0.32. Although this may be affected by the degree of laser deterioration of the Raman spectrometer and the region to which the H element is added in the protective layer, when the relative ratio of the relative intensity of the Raman spectrum derived from the H element exceeds 0.32, the relative intensity of the Raman spectrum derived from the H element can exceed 500 based on the value obtained by integrating the baseline. Here, the "total peak area of ​​the relative intensity of the Raman spectrum in the measurement region" refers to the value obtained by integrating the waveform showing the relative intensity of the Raman spectrum in the measurement region.

[0035] In the magnetic recording medium of the present technology, the wave number is 1000 to 1800 cm ―１ The relative ratio of the relative intensity of the Raman spectrum derived from the H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region is preferably greater than 0.32, more preferably greater than 0.38, and particularly preferably greater than 0.46. Although this may be affected by the degree of laser deterioration of the Raman spectrometer and the region to which the H element is added in the protective layer, when the relative ratio of the relative intensity of the Raman spectrum derived from the H element exceeds 0.32, as described above, the relative intensity of the Raman spectrum derived from the H element typically exceeds 500, based on the value obtained by integrating the baseline. Furthermore, when the relative ratio of the relative intensity of the Raman spectrum derived from the H element exceeds 0.38, the relative intensity of the Raman spectrum derived from the H element typically becomes 600 or greater, and when the relative ratio of the relative intensity of the Raman spectrum derived from the H element exceeds 0.46, the relative intensity of the Raman spectrum derived from the H element typically becomes 700 or greater.

[0036] The relative intensity of the Raman spectrum derived from the H element contained in the protective layer of the magnetic recording medium of the present technology is in the wavenumber range of 1000 to 1800 cm ―１The upper limit of the relative ratio of the relative intensity of the Raman spectrum in the measurement region to the total peak area is not particularly limited, as long as it is within a range that can favorably maintain the cleaning power to remove dirt from the magnetic head during running of the magnetic recording medium. For example, it can be favorably adjusted to a range of 0.53 or less, less than 0.50, less than 0.49, less than 0.47, less than 0.46, etc. Although it may be affected by the degree of deterioration of the laser of the Raman spectrometer and the region where the H element is added in the protective layer, examples of the upper limit values ​​of these relative ratios usually correspond to 1000 or less, less than 900, less than 850, less than 800, less than 750, etc., as the relative intensity of the Raman spectrum derived from the H element, based on the value integrated from the baseline.

[0037] The thickness of the protective layer of the magnetic recording medium of the present technology is not particularly limited, and can be adjusted to any thickness that can fulfill the above-mentioned functions.For example, it may be designed in a range of 10.0 nm or less, 8.0 nm or less, 6.0 nm or less, 5.0 nm or less, etc.In addition, the lower limit of the thickness is not particularly limited, and it may be designed in a range of 1.0 nm or more, 2.0 nm or more, 3.0 nm or more, etc.

[0038] The film thickness of the protective layer can be confirmed, for example, by measuring the cross section of a sample that has been processed and thinned by a focused ion beam (FIB) method or the like using a transmission electron microscope (TEM) according to the following procedure. Note that when measuring the film thickness of the protective layer, if a carbon layer is formed as the protective layer during sample preparation in the following procedure, it may become impossible to distinguish between the protective layer and the protective layer during sample preparation. Therefore, it is not necessary to form a carbon layer as the protective layer during sample preparation.

[0039] A magnetic recording tape using a magnetic recording medium is unwound from a reel or the like housed in a magnetic recording tape cartridge, and three samples are prepared by cutting out the required lengths 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 periphery. Subsequently, each sample is processed and thinned using a method such as FIB (Focused Ion Beam). When using the FIB method, a carbon layer and a tungsten layer are formed as protective layers for measurement (protective layers during sample preparation) as a pretreatment for observing the cross-sectional TEM image described below. The carbon layer is formed on the protective layer side surface and the back layer side surface of the magnetic tape by vapor deposition, and the tungsten layer is further formed on the protective layer side surface by vapor deposition or sputtering. The thinning is performed along the length (longitudinal direction) of the magnetic tape. In other words, the thinning results in a cross section parallel to both the longitudinal and thickness directions of the magnetic tape.

[0040] 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. Device: TEM (H9000NAR manufactured by Hitachi, Ltd.) Acceleration voltage: 300 kV Magnification: 2,000,000 times

[0041] Next, using the TEM image of each obtained thinned sample, the thickness of the layer to be measured is measured at 10 positions aligned in the longitudinal direction of the magnetic tape of each thinned sample. The measured values ​​of each obtained thinned sample (30 measured values ​​in total) are simply averaged (arithmetic mean) to obtain the average value, which is the film thickness (average thickness) [nm] of the layer to be measured. Note that the positions where this measurement is performed are selected randomly from the test piece.

[0042] The method for forming a protective layer on a magnetic recording medium according to the present technology is ―１There are no particular limitations on the method, as long as it can add H element to form a film so that the relative ratio of the relative intensity of the Raman spectrum derived from H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region exceeds 0.32. For example, when using a method of forming a protective layer by sputtering carbon element on the surface of the magnetic layer side of the magnetic recording medium, the sputtering can be carried out in an atmosphere in which a gas consisting of a compound containing H element is added to an inert gas, thereby making it possible to suitably adjust the relative intensity of the Raman spectrum derived from H element contained in the protective layer within the above range.

[0043] The case where this technique is used to form a protective layer by sputtering carbon elements will be specifically described with reference to the drawings.

[0044] 4 is an image diagram of the conventional method of forming a protective layer by sputtering carbon elements. The sputtering is performed in an atmosphere of an inert gas such as Ar gas. By sputtering a sputtering target made of carbon elements (Carbon Target in the figure), a film of carbon elements is formed on the surface of the magnetic recording medium (Substrate in the figure) on the side where the magnetic layer is located, forming a protective layer containing DLC.

[0045] In contrast, FIG. 5 is an illustration of the formation of a protective layer by sputtering carbon elements using this technology. In this case, sputtering is performed in an atmosphere containing an inert gas, such as Ar gas, plus a gas consisting of a compound containing H, such as a hydrocarbon gas. The example shown in FIG. 5 illustrates the use of ethylene as the hydrocarbon gas. By performing sputtering in an atmosphere containing a gas consisting of a compound containing H, as shown in FIG. 5, when a carbon film is formed on the surface of the magnetic recording medium (substrate in the figure) on the side where the magnetic layer is located, the hydrocarbon gas, which is a compound containing H, is incorporated into the film, confirming that H is suitably incorporated into the protective layer. The protective layer formed in this manner contains DLC and H elements. As a result, the components constituting the protective layer approach the lower right region of the ternary phase diagram shown in FIG. 2, as described above, thereby suitably softening the film hardness of the protective layer and achieving suitable tape polishing force.

[0046] In the method for manufacturing a magnetic recording medium according to the present technology, when the protective layer is formed by sputtering, the gas made of a compound containing H element to be added to the inert gas is not particularly limited as long as it is a compound containing H element. Examples of the gas made of a compound containing H element include hydrocarbon gases such as ethylene, propylene, and butene.

[0047] When a protective layer is formed by sputtering in the magnetic recording medium manufacturing method of the present technology, the number of sputtering chambers for forming the protective layer by sputtering may be two or more, depending on the design of the manufacturing equipment for the magnetic recording medium manufacturing process, the manufacturing lead time, etc.

[0048] When the number of sputtering chambers for forming the protective layer by sputtering is two or more, the film formation conditions for the protective layer in each of the two or more sputtering chambers may be the same, or different film formation conditions may be used for each sputtering chamber.

[0049] In this case, for example, the protective layer of the magnetic recording medium of the present technology may be configured to have two or more layers in accordance with the number of sputtering chambers, and may include a protective layer (H-element-added layer) formed in an atmosphere in which a gas made of a compound containing H element is added to an inert gas, and a protective layer (H-element-free layer) formed in an inert gas atmosphere (an atmosphere in which a gas made of a compound containing H element is not added to an inert gas). In this case, the protective layer of the magnetic recording medium of the present technology to be manufactured may have a wavelength of 1000 to 1800 cm. ―１ A H-doped layer in which the relative ratio of the relative intensity of the Raman spectrum attributable to the H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region exceeds 0.32, and a wave number of 1000 to 1800 cm ―１ and one or more H-element non-doped layers in which the relative ratio of the relative intensity of the Raman spectrum derived from H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region does not exceed 0.32.

[0050] Taking into consideration the application and conditions of use of the magnetic recording medium, the protective layer is configured to include an H-element-added layer and an H-element-free layer, thereby adjusting the hardness of the protective film and realizing a suitable tape polishing force. In this case, the order and number of the H-element-added layer and the H-element-free layer that form the protective layer can be arbitrarily designed depending on the application and conditions of use of the magnetic recording medium.

[0051] In this case, the thickness of the H element-added layer can be adjusted to any range within the thickness of the protective layer, taking into account various conditions such as the desired hardness, tape grinding force, the design of the manufacturing equipment for the magnetic recording medium manufacturing process, and the manufacturing lead time. The thickness of the H element-added layer may be designed to be, for example, 3.0 nm or less, 2.0 nm or less, etc. In addition, the lower limit of the thickness of the H element-added layer is not particularly limited, but can be designed to any value within the range of the lower limit of the thickness of the protective layer. In addition, the thickness of the H element-free layer is determined by the thickness of the H element-added layer to be designed relative to the thickness of the protective layer.

[0052] The thicknesses of these H-element-added layers and H-element-unadded layers can be measured, for example, by the same method as used to measure the thickness of the protective layer, with the magnification of the TEM image being adjusted appropriately depending on the thickness of these layers.

[0053] When the protective layer of the magnetic recording medium of the present technology is formed by sputtering in an atmosphere in which a gas consisting of a compound containing an H element is added to an inert gas, the coverage rate of the magnetic layer can also be improved compared to when the protective layer is formed by sputtering in an atmosphere in which a gas consisting of a compound containing an H element is not added.

[0054] The coverage of the magnetic layer can be evaluated, for example, by using the number of counts per second of the elements that make up the magnetic crystal grains contained in the magnetic layer as an indicator when secondary ion mass measurement is performed using a Ga liquid metal ion gun.

[0055] That is, by forming the protective layer of the magnetic recording medium of the present technology by sputtering in an atmosphere in which a gas consisting of a compound containing an H element is added to an inert gas, the coverage rate of the magnetic layer is improved, and therefore, when secondary ion mass measurement is performed on the surface of the magnetic recording medium on which the protective layer is provided using a Ga liquid metal ion gun, the count number per second of the elements constituting the magnetic crystal grains decreases. More specifically, by adding a gas consisting of a compound containing an H element to an inert gas, the count number per second of the elements constituting the magnetic crystal grains in the secondary ion mass measurement can be adjusted to, for example, 200 cps or less, 150 cps or less, 115 cps or less, etc. For example, when ethylene is added to an inert gas as a gas consisting of a compound containing H element, if the ethylene addition ratio to the inert gas is approximately 10%, the number of counts per second of the elements constituting the magnetic crystal particles in the secondary ion mass measurement will be approximately 200 cps, if the ethylene addition ratio is 20%, it will be approximately 150 cps, and if the ethylene addition ratio is 30%, it will be approximately 115 cps.

[0056] The element counted in the secondary ion mass measurement, which can be an index of the coverage rate of the magnetic layer, is not particularly limited as long as it is a component contained in the magnetic layer, but the element constituting the magnetic crystal grains can be suitably used.The element constituting the magnetic crystal grains is not particularly limited as long as it is an element constituting the magnetic crystal grains that can be used in the magnetic recording medium of the present technology.For example, any of the elements Co, Pt, and Cr constituting the magnetic crystal grains described later as specific examples of the magnetic crystal grains may be counted.

[0057] <Substrate Layer> In the magnetic recording medium of the present technology, the substrate layer is a flexible, long, non-magnetic support, and mainly functions as a layer that forms the base of the magnetic recording medium. The substrate layer is sometimes called a base film layer, and may also function as a film layer that imparts appropriate rigidity to the magnetic recording medium.

[0058] The film thickness (average thickness) of the base layer is preferably 4.0 μm or less, more preferably 3.6 μm or less, and even more preferably 3.3 μm or less. By having the film thickness of the base layer within the above numerical range (for example, 4.0 μm or less), the recording capacity that can be recorded in one data cartridge can be increased compared to that of general magnetic tape. The lower limit of the film thickness of the base layer may be determined from the viewpoint of the limitations in film production and the function of the base layer, and may be, for example, 2.0 μm or more, particularly 2.5 μm or more.

[0059] The film thickness of the substrate layer can be determined, for example, as follows. First, a magnetic recording tape using a magnetic recording medium is unwound from a reel or the like housed in a magnetic recording tape cartridge, and the required length is 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 periphery, to prepare three samples. Next, layers other than the substrate layer 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 film thickness of each sample (substrate layer) is measured at five positions, and these measured values ​​(15 points in total) are simply averaged (arithmetic mean) to calculate the film thickness (average thickness) of the substrate layer. Note that the measurement positions are selected randomly from the sample.

[0060] The material constituting the substrate layer is not particularly limited as long as it can realize a flexible, long-length non-magnetic support. For example, it may contain at least one selected from the group consisting of polyesters, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins. These may be used alone or in combination of two or more. When the substrate layer contains two or more of the above materials, the two or more materials may be mixed, copolymerized, or laminated.

[0061] The polyesters may include, for example, at least one selected from the group consisting of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PCT (polycyclohexylene dimethylene terephthalate), PEB (polyethylene-p-oxybenzoate), and polyethylene bisphenoxycarboxylate.

[0062] The polyolefins may include, for example, at least one selected from the group consisting of PE (polyethylene) and PP (polypropylene). The cellulose derivatives may include, for example, at least one selected from the group consisting of cellulose diacetate, cellulose triacetate, CAB (cellulose acetate butyrate), and CAP (cellulose acetate propionate).

[0063] The vinyl resin may include, for example, at least one selected from the group consisting of PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride).

[0064] The other polymer resin may include, for example, at least one selected from the group consisting of PA (polyamide, nylon), aromatic PA (aromatic polyamide, aramid), PI (polyimide), aromatic PI (aromatic polyimide), PAI (polyamideimide), aromatic PAI (aromatic polyamideimide), PBO (polybenzoxazole, for example, 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).

[0065] <Magnetic Layer> In the magnetic recording medium of the present technology, the magnetic layer (recording layer) is a layer containing magnetic crystal grains and can function as a layer that uses magnetism to record or reproduce signals. The magnetic layer 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 magnetic layer has a granular structure containing a Co-based alloy.

[0066] In this case, the magnetic layer having a granular structure is composed of ferromagnetic crystal grains containing a Co-based alloy and non-magnetic grain boundaries (non-magnetic materials) surrounding the ferromagnetic crystal grains. More specifically, the magnetic layer having a granular structure is composed of columns (columnar crystals) containing a Co-based alloy and non-magnetic grain boundaries surrounding the columns and physically and magnetically separating each column. Due to this granular structure, the magnetic layer exhibits a structure in which each columnar magnetic crystal grain is magnetically separated.

[0067] The Co-based alloy has a hexagonal close-packed (hcp) structure, and its c-axis can be oriented perpendicular to the main surface of the magnetic layer (thickness direction of the magnetic recording tape using the magnetic recording medium).In this way, the magnetic crystal grains contained in the magnetic layer have a hexagonal close-packed structure, which further enhances the orientation characteristics of the magnetic layer.As the Co-based alloy, it is preferable to adopt a CoPtCr-based alloy containing at least Co, Pt, and Cr.The CoPtCr-based alloy is not particularly narrowly limited, and may further contain an additional element.For example, the additional element can be at least one element selected from the group consisting of Ni, Ta, etc.Preferably, the magnetic layer can have a granular structure in which particles containing Co, Pt, and Cr are separated by oxides.

[0068] The nonmagnetic grain boundaries surrounding the ferromagnetic crystal grains contain a nonmagnetic metal material. Here, "metal" includes semimetals. The nonmagnetic metal material may be, for example, a nonmagnetic oxide. The nonmagnetic 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.

[0069] The metal oxide suitable for the non-magnetic grain boundary contains, for example, at least one element selected from the group consisting of Si, Al, Ti, Ta, Zr, Ce, Y, B, and Hf, and O (oxygen). More specifically, the metal oxide may be, for example, SiO ２ , Al ２ O ３ , TiO ２ , Ta ２ O ５ , ZrO ２ , CeO ２ , Y ２ O ３ , B ２ O ３ and HfO ２ The metal oxide preferably contains at least one selected from the group consisting of SiO ２ , TiO ２ and B ２ O ３ More preferably, B ２ O ３ Includes.

[0070] From the viewpoint of improving electromagnetic conversion characteristics, the metal oxide suitable for the non-magnetic grain boundary preferably further contains at least one element selected from the group consisting of Co, Cr, etc. More specifically, the metal oxide is Co. ３ O ４ , CoO and Cr ２ O ３ It is preferable that the metal oxide contains at least one selected from the group consisting of Co, etc. ３ O ４ and CoO, and particularly preferably Co ３ O ４ Includes.

[0071] The metal nitride suitable for non-magnetic grain boundaries contains nitrogen and at least one element selected from the group consisting of Si, Cr, Co, Al, Ti, Ta, Zr, Ce, Y, Hf, etc. More specifically, the metal nitride contains at least one element selected from the group consisting of SiN, TiN, AlN, etc.

[0072] The metal oxide is B ２ O ３ The reason why it is considered preferable to include Co 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 interaction acting between ferromagnetic crystal grains by separating the columns of the Co-based alloy, i.e., by spatially separating the ferromagnetic crystal grains. The process by which the sputtered particles reach the base layer 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 constitutes the non-magnetic grain boundaries is lower than the melting point of the material that constitutes the ferromagnetic crystal grains. For example, when Co is used as the material for the ferromagnetic crystal grains, ８０ Pt ２０ If the non-magnetic grain boundary is SiO ２ and TiO ２ In the case of Co, the melting points are 1600°C and 1843°C, respectively. ８０ Pt ２０ It will be higher than B ２ O ３ The melting point of Co is 470°C. ８０ Pt ２０ When the melting point of the non-magnetic grain boundary material is lower than that of the ferromagnetic crystal grains, the ferromagnetic crystal grains precipitate first at the tip of the column of the underlayer, and after the temperature drops as the cooling progresses, the non-magnetic grain boundary material precipitates between the ferromagnetic grains, thereby realizing a good granular structure. ２ O ３ is considered to be suitable (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.).

[0073] For the reasons described above, in the present technology, the magnetic layer 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. That is, the melting point of the material forming the nonmagnetic grain boundaries may preferably be lower than the melting point of the material forming the magnetic crystal grains, for example, by 100°C or more and 1200°C or less, more preferably by 300°C or more and 1100°C or less, and even more preferably by 500°C or more and 1000°C or less.

[0074] In the magnetic recording medium of the present technology, the magnetic layer has an average atomic ratio (also referred to as average composition) represented by the following formula (1). Note that the following formula (1) does not indicate a specific crystal structure, but simply represents the average atomic ratio of elements. In other words, the following formula (1) represents a value obtained from the results of measuring the atomic ratio of elements. Furthermore, the magnetic layer may contain elements other than those represented by the following formula (1). In other words, the magnetic layer may contain other elements (e.g., impurities, diffused components from other layers, etc.) as long as it has the average atomic ratio represented by the following formula (1).

[0075] [Co （１００－Ｗ－Ｘ） Pt Ｗ Cr Ｘ ] （１００－Ｙ－Ｚ） - (M1O Ｍ ) Ｙ - (M2O Ｎ ) Ｚ ... (1) (In the above formula (1), W, X, Y, and Z are 10≦W≦25, 8≦X≦16, 6≦Y≦11, and 0≦Z≦5, respectively, and MO Ｍ , M2O Ｎ indicates metal oxides.)

[0076] When W, X, Y, and Z are in the ranges of 10≦W≦25, 8≦X≦16, 6≦Y≦11, and 0≦Z≦5, respectively, the magnetic layer of the magnetic recording medium can exhibit higher electromagnetic conversion characteristics.

[0077] In the above formula (1), the lower limit of W is preferably 12≦W≦W, more preferably 14≦W≦W, even more preferably 16≦W≦W, and particularly preferably 18≦W≦W. The upper limit of W is preferably W≦23. The numerical range of W may be defined by any of the above upper limits and any of the above lower limits, and is preferably 12≦W≦23, more preferably 14≦W≦23, even more preferably 16≦W≦23, and particularly preferably 18≦W≦23.

[0078] In the above formula (1), the lower limit of X is preferably 10≦X. The upper limit of X is preferably X≦14, more preferably X≦12. 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 8≦X≦14, more preferably 8≦W≦12, and even more preferably 10≦W≦12.

[0079] In the above formula (1), the lower limit of Y is preferably 7≦Y. The upper limit of Y is preferably Y≦10, more preferably Y≦9. 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 6≦Y≦10, more preferably 6≦Y≦9, and even more preferably 7≦Y≦9.

[0080] In the above formula (1), the lower limit of Z is preferably 0<Z, more preferably 0.5≦Z, and even more preferably 1≦Z. The upper limit of Z is preferably Z≦4, and more preferably Z≦3. 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 0<Z≦5, more preferably 0.5≦Z≦4, and even more preferably 1≦Z≦3.

[0081] M1O in the above formula (1) Ｍ For example, the metal oxide includes at least one element selected from the group consisting of Si, Al, Ti, Ta, Zr, Ce, Y, B, and Hf. More specifically, for example, MO in the above formula (1)Ｍ is SiO ２ , Al ２ O ３ , TiO ２ , Ta ２ O ５ , ZrO ２ , CeO ２ , Y ２ O ３ , B ２ O ３ and HfO ２ and the like. Ｍ is preferably SiO ２ , TiO ２ and B ２ O ３ More preferably, B ２ O ３ Includes.

[0082] M2O in the above formula (1) Ｎ For example, the metal oxide includes at least one element selected from the group consisting of Co, Cr, etc. More specifically, for example, MO in the above formula (1) Ｎ is Co ３ O ４ , CoO and Cr ２ O ３ The compound of formula (1) above contains at least one selected from the group consisting of M2O Ｎ is preferably Co ３ O ４ and CoO, more preferably Co ３ O ４ Includes.

[0083] The average atomic ratio of the magnetic layer can be determined, for example, as follows. First, a magnetic recording tape using a magnetic recording medium housed in a magnetic recording tape 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 periphery, to prepare three samples. Next, the back layer on the back surface (the surface on the back layer side) of each sample is removed using methyl ethyl ketone to obtain three specimens. The back surface of each sample (the surface from which the back layer has been removed) is subjected to FIB (Focused Ion Beam) treatment to remove layers from the base layer to the magnetic layer of each sample. In the example of the magnetic recording medium T shown in FIG. 1 , the base layer 5, seed layer 4 (first seed layer 41 and second seed layer 42), and underlayer 3 (first underlayer 31 and second underlayer 32) are removed. This results in three analysis samples, with the layers from the magnetic layer to the surface side of the magnetic recording medium remaining. In the example of the magnetic recording medium T shown in Figure 1, only the magnetic layer 1, the protective layer P, and the lubricant layer L remain. For each of the obtained analysis samples, 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 samples are analyzed by energy dispersive X-ray spectroscopy (EDX) to identify the average atomic ratio of each element contained in the magnetic layer. The measurement conditions for the TEM and elemental analyzer, as well as a more detailed identification procedure for the average atomic ratio, are described below.

[0084] (TEM measurement conditions) Scanning transmission electron microscope: JEM-ARM200F manufactured by JEOL Ltd. Acceleration voltage: 200 kV Beam diameter: approximately 0.2 nmΦ Magnification: 2,000,000 times

[0085] (Measurement conditions for elemental analyzer) Elemental analyzer: JED-2300T manufactured by JEOL Ltd. X-ray detector: Si drift detector Energy resolution: about 140 eV X-ray take-off angle: 21.9° Solid angle: 0.98 sr

[0086] (Procedure for Identifying Average Atomic Ratio) (1) Ratio of Co, Pt, and Cr Using a TEM image of the cross section of the magnetic layer of the analytical sample, EDX analysis is performed at five locations within the metal column to identify the average atomic ratio of Co, Pt, and Cr. This results in the values ​​of W and X in formula (1) above. (2) Qualitative Analysis of M1 and M2 Using a TEM image of the cross section of the magnetic layer of the analytical sample, qualitative analysis of M1 and M2 in formula (1) above is performed by EDX at five locations on the boundaries between the metal column and the oxide. (3) Ratio of Metal to Oxide Using image analysis software "ImageJ" (available from the National Institutes of Health, USA), the area ratio of the metal columns (black areas) to the oxides (white areas) in the planar TEM image (field of view containing 100 or more columns) is determined. From this area ratio, the volume ratio of the oxide is determined. From this volume ratio, the element ratio of the oxide to the metal is determined. This gives the values ​​of Y and Z in the above formula (1).

[0087] Details of the above process using ImageJ are shown below. (Process for measuring black area by binarization process) ImageJ is used to process as follows. In this process, the image processing range is set to 80 nm x 80 nm. Specific operating procedures for the software are shown in parentheses for each of the following steps. Step 1: Open the image file. (File → Open) Step 2: Input 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: Convert the image type to an 8-bit grayscale image. (Image menu > Type > 8 bit) Step 4: Remove noise. (Process menu > Smooth) Step 5: Binarize. (Process (Processing menu) > Binary (Binarization) > Make Binary (Make the image black and white)) Step 6: Analyze (Analyze (Analysis menu) → Analyze Particles (Particle analysis)) In this analysis, the thresholds are set as follows: Size (Pixel^2): 100-10000 Circularity: 0.00-1.00 Show: Masks After setting the thresholds, checking Summarize will display the Summary screen. In this Summary screen, the Count (number of particles), Total Area (total area), Average size (number of particles), Area Function (percentage of area occupied by particles), and Mean are displayed. Step 7: The above steps 1 to 6 are performed on the images of five locations in the analysis sample, and the average value (simple average) of the obtained Area Functions (ratio of the area occupied by the particles) is calculated. These average values ​​correspond to the area ratio of the metal element ((100-Y-Z) in the above formula (1)). When Z<0, if only the ratio of MO is calculated using the above value (100-Y-Z), O will remain.Z can be calculated from the element ratio of this remaining O and MO. When Z=0, if only the ratio of MO is calculated using the above value (100-Y-Z), there will be no remaining O.

[0088] 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.

[0089] Magnetic layer thickness (average thickness) t ｍ is preferably 10.0 nm or more and 20.0 nm or less, more preferably 11.0 nm or more and 19.0 nm or less, and even more preferably 12.0 nm or more and 18.0 nm or less.

[0090] The thickness of the magnetic layer can be measured, for example, by the same method as used to measure the thickness of the protective layer, with the TEM image magnification adjusted appropriately depending on the thickness of the magnetic layer.

[0091] <Lubricant Layer> The magnetic recording medium of the present technology may have a lubricant layer containing a lubricant on the outside of the protective layer. The lubricant layer is a layer containing a lubricant, and its main function is to reduce friction of the magnetic recording tape using the magnetic recording medium during running. The lubricant layer contains at least one type of lubricant. The lubricant layer may further contain various additives, such as a rust inhibitor, as necessary.

[0092] The lubricant contained in the lubricant layer preferably contains one or more compounds having a fluorine hydrocarbon group. Examples of the compound having a fluorine hydrocarbon group include carboxylic acid compounds having at least two carboxyl groups and one ester bond and represented by the following general formula (a). The lubricant layer may further contain compounds other than the compound having a fluorine hydrocarbon group, and may further contain a type of lubricant other than the carboxylic acid compound represented by the following general formula (a).

[0093] (In the above general formula (a), Rf is an unsubstituted or substituted, saturated or unsaturated, fluorine-containing hydrocarbon group, Es is an ester bond, and R is, although it may be absent, an unsubstituted or substituted, saturated or unsaturated hydrocarbon group.)

[0094] The carboxylic acid compound is preferably one represented by the following general formula (b) or (c).

[0095] (In the above general formula (b), Rf is an unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group.)

[0096] (In the above general formula (c), Rf is an unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group.)

[0097] The lubricant layer may contain one or both of the carboxylic acid compounds represented by the above general formula (b) and general formula (c).

[0098] When a lubricant containing a carboxylic acid compound represented by the above general formula is applied to the surface of a magnetic recording medium such as a protective layer, a lubricating effect is exhibited due to the cohesive force between the fluorine-containing hydrocarbon groups Rf, which are hydrophobic groups.

[0099] When the Rf group of the carboxylic acid compound represented by the above general formula is a fluorine-containing hydrocarbon group, it preferably has a total carbon number of 6 to 50 and a total carbon number of the fluorinated hydrocarbon group of 4 to 20. The Rf group may be saturated or unsaturated, linear or branched, or cyclic, but is particularly preferably saturated and linear.

[0100] When the Rf group is a fluorine-containing hydrocarbon group, it is preferably a group represented by the following general formula (e).

[0101] (However, in general formula (e), m and n are each an integer selected from the following ranges, where m is 2 or more and 20 or less, and n is 3 or more and 18 or less, and more preferably m is 4 or more and 13 or less, and n is 3 or more and 10 or less.)

[0102] The fluorohydrocarbon groups may be concentrated in one location as described above or dispersed as shown in the following general formula (f): -CF ３ Ya-CF ２ - and also - CHF ２ or -CHF-.

[0103] (However, in general formula (f), n1+n2=n, m1+m2=m.)

[0104] The reason for limiting the number of carbon atoms in the general formulas (e) and (f) as above is that when 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 lubricating action is exhibited, and friction and wear durability are improved. On the other hand, when the number of carbon atoms is equal to or less than the upper limit, the solubility of the lubricant made of the carboxylic acid compound in the solvent is maintained good.

[0105] 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, separating 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 it is a hydrocarbon chain with a relatively small number of carbon atoms. 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, and the like in addition to the functional groups described above.

[0106] The carboxylic acid compound represented by the above general formula 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) 10COOCH(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

[0107] The carboxylic acid compound represented by the above general formula is soluble in non-fluorinated solvents that have a small impact on the environment, and has the advantage that it can be subjected to coating, immersion, spraying, etc., using general-purpose solvents such as hydrocarbon solvents, ketone solvents, alcohol solvents, ester solvents, etc. Specific examples of solvents that can be used 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.

[0108] Since the protective layer of the magnetic recording medium of the present technology contains DLC, when a lubricant layer is applied to the surface of the protective layer, the presence of two carboxyl groups and at least one ester bond group, which are the polar bases of the carboxylic acid compound represented by the above general formula, contained in the protective layer increases the cohesive force and adsorption force due to the interaction between the DLC and the hydrophobic group of the carboxylic acid compound, making it possible to form a lubricant layer with good durability.

[0109] The lubricant may not only be held as a lubricant layer on the surface of the magnetic recording medium as described above, but may also be contained in layers such as the magnetic layer and protective layer that constitute the magnetic recording medium.

[0110] The amount of lubricant in the lubricant layer can be calculated, for example, by measuring the number of counts per second of a peak corresponding to the fluorine 1s orbital derived from a lubricant compound having a fluorine hydrocarbon group using X-ray photoelectron spectroscopy.

[0111] In the magnetic recording medium of the present technology, by including H element in the protective layer, the surface of the lubricant layer is ―６ When measurement is performed by X-ray photoelectron spectroscopy at a setting of 6 kV / 20 mA at a pressure of 100 Pa or less, the counts per second of the peak corresponding to the fluorine 1s orbital can be adjusted to 32 kcps or less.

[0112] The lower limit of the number of counts per second of the peak corresponding to the fluorine 1s orbital in the measurement by the X-ray photoelectron spectroscopy is, for example, 10 kcps or more, 20 kcps or more, or 28 kcps or more.

[0113] <Seed Layer> The magnetic recording medium of the present technology may have a seed layer between the substrate layer and the magnetic layer. Furthermore, if the magnetic recording medium further includes an underlayer, which will be described later, the seed layer is provided between the substrate layer and the underlayer. In this case, as shown in FIG. 1 , the substrate layer 5, seed layer 4, underlayer 3, magnetic layer 1, and protective layer P are stacked in this order. The seed layer may have a structure of two or more layers, such as the first seed layer 41 and second seed layer 42 in FIG. 1 .

[0114] The seed layer 12 is preferably provided from the viewpoint of ensuring a good SNR when the underlayer and intermediate layer described below are formed thinly or even in a layer configuration in which the underlayer and intermediate layer are not provided. The seed layer 12 may have the function of adhering the underlayer 13 and the upper layers thereof, i.e., the underlayer 13 and the recording layer 14, etc., to the substrate 11.

[0115] When the seed layer has a structure of two or more layers, the seed layer provided on the substrate layer side (second seed layer 42 in FIG. 1) is preferably in an amorphous state. The seed layer provided on the substrate layer side preferably contains three atoms, Ti, Cr, and O, and may have a composition with an average atomic ratio represented by the following formula (2A), for example. The seed layer is particularly (TiCr) ９８ O ２ It may be formed from

[0116] (TiCr) （１００－ｘ） O ｘ ... (2A) (However, in formula (2A), x is, for example, 1≦x≦10, preferably 1≦x≦5, more preferably 1≦x≦3, and even more preferably x=2.)

[0117] In the above formula (2A), when x is too large (for example, when it exceeds 10), TiO ２ This is undesirable because it causes crystals to be generated, significantly reducing the function of the amorphous layer.

[0118] The Ti metal element has a hexagonal close-packed (hcp) structure in its crystal structure, similar to that of a Co-based alloy. By including Ti in the seed layer (particularly the seed layer provided on the substrate layer side), the matching of the crystal structure between the magnetic layer having the hexagonal close-packed (hcp) structure and the seed layer is improved.

[0119] Furthermore, the seed layer (particularly the seed layer provided on the substrate layer side) contains three atoms of Ti, Cr, and O, which improves the matching of the crystal structure of the seed layer with a magnetic layer that also contains Cr. Furthermore, in the case where the magnetic recording medium further includes an underlayer, and the underlayer contains Cr, the matching of the crystal structure of the underlayer and the seed layer also improves by containing three atoms of Ti, Cr, and O in the seed layer (particularly the seed layer provided on the substrate layer side).

[0120] When the seed layer has a structure of two or more layers, the seed layer (first seed layer 41 in FIG. 1) laminated on the seed layer provided on the base layer side is preferably in a crystalline state. The seed layer preferably contains an alloy containing Ni and W, and more preferably is made of an alloy containing Ni and W. The alloy may have an average atomic ratio represented by, for example, the following formula (2B). The seed layer, in particular, contains Ni ９４ W ６ It may be formed from

[0121] Ni （１００－ｘ） W ｘ ... (2B) (However, in formula (2B), x is, for example, 1≦x≦10, preferably 2≦x≦10, more preferably 4≦x≦8, and even more preferably x=6.)

[0122] The seed layer may contain oxygen because oxygen originating from or resulting from the film constituting the substrate layer penetrates into the seed layer. That is, the seed layer of a magnetic recording medium has a different atomic composition from the seed layer of a hard disk drive (HDD), which does not use a substrate layer made of a film.

[0123] The film thickness (average thickness) of the seed layer 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.

[0124] When the seed layer has a structure of two or more layers, the thickness of the seed layer provided on the substrate layer side 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.

[0125] In this case, the thickness of the seed layer stacked on the seed layer provided on the substrate layer side 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.

[0126] The thicknesses of these seed layers can be measured, for example, by the same method as that used to measure the thickness of the protective layer described above. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of these layers. Similarly, the thickness of each seed layer provided when the seed layer has a structure of two or more layers can also be measured by the same method.

[0127] <Underlayer> When the magnetic recording medium of the present technology includes a seed layer, it may further include an underlayer. In this case, the underlayer is provided between the seed layer and the magnetic layer. More specifically, as shown in FIG. 1 , a substrate layer 5, a seed layer 4, an underlayer 3, a magnetic layer 1, and a protective layer P are stacked in this order. Note that the underlayer may have a structure of two or more layers, such as the first underlayer 31 and the second underlayer 32 in FIG. 1 .

[0128] The underlayer is preferably provided from the viewpoint of improving the orientation characteristics (granularity) of the magnetic layer. Therefore, it is preferable that the underlayer contains a crystalline structure similar to that of the magnetic crystal grains contained in the magnetic layer. For example, when the magnetic crystal grains contained in the magnetic layer are Co-based alloys, the material forming the underlayer preferably contains a material having a hexagonal close-packed structure similar to that of the Co-based alloy, and the c-axis of this structure is preferably oriented perpendicular to the main surface of the underlayer (thickness direction of the magnetic recording medium). This further improves the crystalline orientation characteristics of the magnetic layer and can achieve relatively good matching of the lattice constants between the underlayer and the magnetic layer.

[0129] Because the material constituting the underlayer and the material constituting the layer immediately below the underlayer (the first seed layer in the configuration shown in FIG. 1 ) are different, their crystal structures may not match, and the crystallographic alignment state may differ. As mentioned above, the underlayer has the role of enhancing the crystalline orientation characteristics of the magnetic layer. For this reason, it is preferable to design the underlayer to a thickness that can enhance the crystalline orientation characteristics of the magnetic layer, taking into account the crystallographic alignment state with the material constituting the layer immediately below. Furthermore, from the above perspective, the underlayer may be designed to have a structure of two or more layers.

[0130] When the underlayer is configured with two or more layers, the underlayer provided on the substrate layer side (second underlayer 32 in FIG. 1) 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. When the second underlayer contains ruthenium, a ruthenium alloy, or a Co-based alloy, the lattice matching with the CoCrPt-based alloy contained in the magnetic layer is improved. This can improve the orientation characteristics of the magnetic layer.

[0131] The Co-based alloy preferably has an average atomic ratio represented by the following formula (3A):

[0132] Co （１００－ｙ） Cr ｙ ... (3A) (However, in formula (3A), y is within the range of 35≦y≦45, for example.)

[0133] The film thickness (average thickness) of the second underlayer is preferably 1.0 nm to 50.0 nm, more preferably 5.0 nm to 50.0 nm. When the second underlayer contains ruthenium alone or a ruthenium alloy, the film thickness of the second underlayer is even more preferably 2.0 nm to 20.0 nm, particularly preferably 2.0 nm to 8.0 nm, or 3.0 nm to 7.0 nm. When the second underlayer contains a Co-based alloy, the average thickness of the second underlayer is even more preferably 10.0 nm to 50.0 nm, even more preferably 20.0 nm to 50.0 nm, particularly preferably 25.0 nm to 45.0 nm.

[0134] When the underlayer is composed of two or more layers, the underlayer (first underlayer 31 in FIG. 1) stacked on the underlayer provided on the base layer side preferably contains ruthenium alone, a ruthenium alloy, or a Co-based alloy, more preferably contains ruthenium alone, and even more preferably is made of ruthenium alone. Ruthenium crystals have a hexagonal close-packed (hcp) structure. When the first underlayer contains ruthenium, a ruthenium alloy, or a Co-based alloy, the lattice matching with the CoCrPt-based alloy contained in the magnetic layer is improved. This can further improve the orientation characteristics of the magnetic layer.

[0135] When the second underlayer contains ruthenium or a ruthenium alloy, the first underlayer preferably contains ruthenium or a ruthenium alloy.When the second underlayer contains a Co-based alloy, the first underlayer preferably contains a Co-based alloy.

[0136] The Co-based alloy preferably contains Cr and a metal oxide. The metal oxide contained in the Co-based alloy is preferably silicon dioxide (SiO ２ ) or titanium dioxide (TiO ２ The Co-based alloy more preferably has an average atomic ratio represented by the following formula (3B):

[0137] [Co （１００－ｙ） Cr ｙ ] （１００－ｚ） (MO ２ ) ｚ...(3B) (wherein, in formula (3B), y is within the range of, for example, 35≦y≦45, z is within the range of, for example, z≦10, and M is, for example, Si or Ti.)

[0138] In the above formula (3B), 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 not preferable.

[0139] The thickness of the first underlayer is preferably 1.0 nm to 30.0 nm, more preferably 5.0 nm to 25.0 nm. When the first underlayer contains ruthenium or a ruthenium alloy, the thickness of the first underlayer is even more preferably 10.0 nm to 20.0 nm, particularly preferably 15.0 nm to 20.0 nm. When the first underlayer contains a Co-based alloy, the average thickness of the first underlayer is preferably 1.0 nm to 30.0 nm, more preferably 5.0 nm to 25.0 nm. The first underlayer serves to make the columns of the magnetic layer convex. A thicker first underlayer is preferable to make the columns convex, but the thicker the first underlayer, the more the crystal orientation characteristics deteriorate. The thickness of the first underlayer is preferably designed to a suitable thickness that can balance the function of making the columns convex and the crystal orientation characteristics of the magnetic layer, taking into account the crystallographic matching state with the material constituting the second underlayer directly below.

[0140] The thickness of the underlayer is preferably 10.0 nm to 60.0 nm, more preferably 15.0 nm to 55.0 nm. When the seed layer contains ruthenium alone or a ruthenium alloy, the thickness of the underlayer is even more preferably 15.0 nm to 40.0 nm, particularly preferably 20.0 nm to 40.0 nm, or 20.0 nm to 35.0 nm. When the seed layer contains a Co-based alloy, the thickness of the underlayer is even more preferably 40.0 nm to 55.0 nm, particularly preferably 45.0 nm to 55.0 nm.

[0141] The thickness of the underlayer can be measured, for example, by the same method as that used to measure the thickness of the protective layer. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of these layers. Similarly, when the underlayer has a structure of two or more layers, the thickness of each underlayer can be measured by the same method.

[0142] <Intermediate Layer> When the magnetic recording medium of the present technology includes an underlayer, it may also include an intermediate layer. In this case, the intermediate layer is provided between the underlayer and the magnetic layer. More specifically, as shown in the cross-sectional view of a modified example of the configuration of the magnetic recording medium of the present technology in Figure 6, a substrate layer 5, a seed layer 4, an underlayer 3, an intermediate layer 2, a magnetic layer 1, and a protective layer P are stacked in this order. Note that the intermediate layer may have a structure of two or more layers depending on the purpose and use of the magnetic recording medium.

[0143] The magnetic recording medium of the present technology can further improve the orientation characteristics (granularity) of the magnetic layer by providing an intermediate layer in addition to the underlayer. Therefore, it is preferable that the intermediate layer contains a crystalline structure similar to the magnetic crystal grains contained in the magnetic layer. For example, when the magnetic crystal grains contained in the magnetic layer are a Co-based alloy, it is preferable that the material forming the intermediate layer contains a material having a hexagonal close-packed structure similar to the Co-based alloy, and the c-axis of this structure is oriented perpendicular to the main surface of the intermediate layer (thickness direction of the magnetic recording medium). This further improves the crystalline orientation characteristics of the magnetic layer and improves the matching of the lattice constants between the intermediate layer and the magnetic layer.

[0144] When the magnetic crystal grains contained in the magnetic layer are a Co-based alloy, the material of the intermediate layer is preferably a material that forms a hexagonal close-packed structure. Ru is an example of such a material. From this perspective, the intermediate layer preferably contains Ru alone or an alloy thereof. The Ru alloy is, for example, RuCoCr (TiO ２ ), Ru—SiO ２ , RuTiO ２ , or Ru—ZrO ２ The Ru alloy may preferably have an average atomic ratio represented by the following formula (5):

[0145] [Ru ｘ Coｙ Cr （１００－ｘ－ｙ） ] （１００－ｚ） (MO ２ ) ｚ ... (5) (wherein, in formula (5), x is, for example, 10≦x≦40, and preferably 15≦x≦35; y is, for example, 20≦y≦50, and preferably 25≦y≦45; z is, for example, 1≦z≦30, and more preferably 5≦z≦25; and M is, for example, Ti or Si.)

[0146] Ru is a rare metal, and from the viewpoint of cost, it is preferable to make the intermediate layer as thin as possible, preferably to have an average thickness of 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 also possible to completely eliminate this intermediate layer.

[0147] Furthermore, by utilizing the "wettability" of the intermediate layer, the material constituting the magnetic layer formed on the intermediate layer by vacuum deposition can be easily diffused during crystallization, thereby increasing the column size of the crystals. For example, to ensure that a Ru-containing intermediate layer exhibits wettability, it is preferable that the thickness of the intermediate layer be at least 0.5 nm.

[0148] The thickness of the intermediate layer can be measured, for example, by the same method as that used to measure the thickness of the protective layer. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of these layers. Similarly, when the intermediate layer is configured with two or more layers, the thickness of each intermediate layer can be measured by the same method.

[0149] <Back Layer> The magnetic recording medium of the present technology may have a back layer on the surface of the substrate layer opposite the surface facing the magnetic layer. In this case, as shown in Fig. 1, the back layer 6, substrate layer 5, magnetic layer 1, and protective layer P are stacked in this order. The example of the magnetic recording medium shown in Fig. 1 is a case where the above-mentioned seed layer and underlayer are included, and an example is shown in which the back layer 6, substrate layer 5, seed layer 4 (first seed layer 41 and second seed layer 42), underlayer 3 (first underlayer 31 and second underlayer 32), magnetic layer 1, protective layer P, and lubricant layer L are stacked in this order.

[0150] The back layer plays a role in controlling friction that occurs when a magnetic recording tape using a magnetic recording medium runs at high speed facing a magnetic head, and in preventing winding irregularities, etc. In other words, it plays a fundamental role in ensuring stable running of the magnetic recording tape at high speed.

[0151] The back layer may contain a binder and a non-magnetic powder. The back layer may further contain at least one additive selected from the group consisting of a lubricant, a curing agent, an antistatic agent, etc., as necessary. As the binder, a resin having a structure in which a crosslinking reaction is imparted to a polyurethane resin or a vinyl chloride resin, etc., is preferred. However, the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required of the magnetic recording medium. The resin to be blended is not particularly limited, as long as it is a resin commonly used in coating-type magnetic recording media.

[0152] Examples of the binder 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. At least one selected from the group consisting of the above.

[0153] The binder may also contain a thermosetting resin or a reactive resin, and may contain, for example, at least one selected from the group consisting of 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.

[0154] In addition, in order to improve the dispersibility of the magnetic powder, each of the above-mentioned binders contains -SO ３ M, -OSO ３ M, -COOM, P=O(OM) ２ In the formula, M is a hydrogen atom or an alkali metal such as lithium, potassium, or sodium.

[0155] The polar functional groups include -NR1R2, -NR1R2R3 ＋ X － A side chain type having a 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.

[0156] The non-magnetic powder contained in the back layer may include, for example, at least one selected from the group consisting of inorganic particles and organic particles. These may be used alone or in combination of two or more types of non-magnetic powders. 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 powder may be, for example, acicular, spherical, cubic, plate-like, or other shapes, but is not particularly limited to these.

[0157] The non-magnetic powder contained in the back layer preferably has an average particle size of 10 nm or more and 150 nm or less, more preferably 15 nm or more and 110 nm or less. The non-magnetic powder may have two or more particle size distributions.

[0158] The curing agent that can be contained in the back layer 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.

[0159] The lubricant that can be contained in the back layer can be suitably the lubricant that can be used in the lubricant layer described above. That is, the explanation about the lubricant that can be contained in the lubricant layer also applies to the lubricant that can be contained in the back layer. As the antistatic agent that can be contained in the back layer, a commercially available antistatic agent can be used, and adding the antistatic agent can prevent the adhesion of dirt and dust to the back layer.

[0160] The upper limit of the thickness of the back layer is preferably 0.6 μm or less. By setting the upper limit of the thickness of the back layer to 0.6 μm or less, it is possible to maintain running stability of the magnetic recording tape in a recording and reproducing device using the magnetic recording medium. Although the lower limit of the thickness of the back layer is not particularly limited, for example, by setting it to 0.2 μm or more, it is possible to preferably ensure running stability of the magnetic recording tape in a recording and reproducing device.

[0161] The thickness of the back layer is determined as follows: First, the thickness t Ｔ The thickness [μm] of the back layer is measured using a laser hologram in the same manner as the thickness of the substrate layer described above. Subsequently, the back layer of the sample is removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Thereafter, the measurement is again performed in the same manner. Note that the measurement position is selected randomly from the sample, as in the case of the thickness of the substrate layer described above. Then, the average thickness t of the back layer is calculated using the following formula: ｂ [μm] is calculated using the following formula: ｂ [μm] = t Ｔ [μm]-t Ｂ [μm]

[0162] <CAP Layer> The magnetic recording medium of the present technology may further include a CAP layer. In this case, the CAP layer is provided between the magnetic layer and the protective layer. More specifically, as shown in the cross-sectional view of a modified example of the configuration of the magnetic recording medium of the present technology in FIG. 7, a substrate layer 5, a magnetic layer 1, a CAP layer C, and a protective layer P are stacked in this order. The example of the magnetic recording medium shown in FIG. 7 also includes the seed layer, underlayer, and back layer described above, and shows an example in which a back layer 6, a substrate layer 5, a seed layer 4 (first seed layer 41 and second seed layer 42), an underlayer 3 (first underlayer 31 and second underlayer 32), a magnetic layer 1, a CAP layer C, a protective layer P, and a lubricant layer L are stacked in this order.

[0163] The CAP layer is a layer containing a material with strong magnetic interaction. A laminated structure consisting of a magnetic layer having a granular structure and a CAP layer is generally called a Coupled Granular Continuous (CGC) structure.

[0164] The CAP layer may contain a CoPtCr-based material. The CoPtCr-based material includes, for example, a CoPtCr material, a CoPtCrB material, or a material 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, MON in the following formula (4B)) includes at least one selected from the group consisting of Si, Ti, Mg, Ta, and Cr. More specifically, the metal oxide may be, for example, SiO ２ , TiO ２ , MgO, Ta ２ O ５ , Cr ２ O ３ or a mixture of two or more thereof. The CAP layer preferably includes a CoPtCrB material. That is, the CAP layer is preferably a layer including an alloy containing Co, Pt, Cr, and B.

[0165] The material contained in the CAP layer preferably has an average atomic ratio shown in the following formula (4A) or (4B), for example.

[0166] Co(100-xy-z)Pt ｘ Cr ｙ Bｚ ... (4A) (However, in formula (4A), x is, for example, 5≦x≦30, y is, for example, 5≦y≦20, and z is, for example, 0≦z≦15, preferably 10≦z≦30.)

[0167] (Co(100-xy-z)Pt ｘ Cr ｙ B ｚ ) １００－ｐ - (MON) ｐ ...(4B) (wherein, in formula (4B), x is, for example, 5≦x≦30, y is, for example, 5≦y≦20, z is, for example, 0≦z≦15, preferably 5≦z≦12, MON is the metal oxide, and p is, for example, 5≦p≦15.)

[0168] The thickness of the CAP layer is preferably 4.0 nm or more, more preferably 5.0 nm or more. By making the thickness of the CAP layer 4.0 nm or more, a higher SNR can be obtained. Furthermore, the saturation magnetic field (Hs) of the magnetic layer can be reduced. The upper limit of the thickness of the CAP layer is not particularly limited, but can be set to, for example, 10.0 nm or less.

[0169] The thickness of the CAP layer can be measured, for example, by the same method as that used to measure the thickness of the protective layer, except that the magnification of the TEM image is adjusted appropriately depending on the thickness of the CAP layer.

[0170] <SUL Layer (Soft Magnetic Underlayer)> The magnetic recording medium of the present technology may further include a soft magnetic underlayer (SUL). In this case, the SUL layer is provided between the substrate layer and the magnetic layer. More specifically, as shown in the cross-sectional view of FIG. 8 , which illustrates a modified example of the configuration of the magnetic recording medium of the present technology, the SUL layer is provided between the substrate layer 5 and the seed layer 4. The example of the magnetic recording medium shown in FIG. 8 includes the seed layer, underlayer, and back layer described above, and illustrates an example in which the back layer 6, substrate layer 5, SUL layer 7, seed layer 4 (first seed layer 41 and second seed layer 42), underlayer 3 (first underlayer 31 and second underlayer 32), magnetic layer 1, CAP layer C, protective layer P, and lubricant layer L are stacked in this order.

[0171] The SUL layer is a layer provided to efficiently draw leakage magnetic flux generated from a magnetic head into the magnetic layer when magnetic recording is performed on the magnetic layer. In other words, by providing the SUL layer, the magnetic field strength from the magnetic head can be increased, resulting in a magnetic recording medium suitable for higher density recording. Note that a magnetic recording medium equipped with an SUL layer can also be called a "dual-layer perpendicular magnetic recording medium."

[0172] By disposing the SUL layer below the perpendicular alignment film of the magnetic recording medium, the surface magnetization induced on the film surface when recording perpendicularly to the perpendicular alignment film is canceled, and the demagnetizing field generated inside the perpendicular alignment film is suppressed. Generally, in perpendicular magnetic recording, the best performance can be achieved by combining a single-pole type magnetic head that can generate a steep recording magnetic field in the perpendicular direction with a magnetic recording medium having an SUL layer.

[0173] The saturation magnetization Ms of the SUL layer is preferably 400 emu / cm ３ Above, 500 emu / cm ３ By adjusting the above, the magnetic flux generated by the magnetic head can be suitably passed through, and the recording efficiency to the magnetic layer can be improved. In addition, the saturation magnetization Ms of the SUL layer is, for example, 1400 emu / cm ３ Below, 1000 emu / cm ３ By adjusting the following, the influence of the residual magnetization of the SUL layer can be reduced, and when erasing a part of the magnetization already recorded in the magnetic layer, it can be suitably erased. The amount of saturation magnetization of the SUL layer can be adjusted appropriately by changing the type and ratio of the constituent materials.

[0174] The SUL layer includes a soft magnetic material in an amorphous state. The amorphous soft magnetic material can be, for example, a Co-based material such as a CoZrNb alloy. Other examples of the soft magnetic material include CoZrTa and CoZrTaNb. Alternatively, an Fe-based material such as FeCoB, FeCoZr, FeCoTa, or CoFeTaZr may be used. These materials may be used alone or in combination. The SUL layer may 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.

[0175] The thickness of the SUL layer is not particularly limited, but by setting it in the range of, for example, 10.0 nm or more and 30 nm or more, it can fully function as a path for the recording magnetic field when recording with a single-pole type recording head, and can achieve saturated recording. Furthermore, by setting the upper limit of the SUL layer thickness in the range of, for example, 100.0 nm or less and 50 nm or less, deformation of the magnetic recording tape using the magnetic recording medium due to the stress of the SUL layer can be suppressed, and stable contact with the magnetic head performing recording or playback can be achieved. The thickness of the SUL layer can be measured, for example, by the same method as for measuring the thickness of the protective layer described above. However, the magnification of the TEM image is appropriately adjusted depending on the thickness of the SUL layer.

[0176] The magnetic recording medium of the present technology can be designed by arbitrarily combining the above-mentioned layers according to the purpose and application. For example, as shown in the cross-sectional view of a modified example of the configuration of the magnetic recording medium of the present technology in FIG. 9, it may have a configuration including all of the above-mentioned layers.

[0177] <Other Layers> The magnetic recording medium of the present technology may include other layers in addition to the above-described configuration, as needed, as long as the desired physical properties are not significantly impaired.

[0178] The film thickness of the entire magnetic recording medium of the present technology can be adjusted by arbitrarily combining the above-mentioned layers. The preferred range of the film thickness of the entire magnetic recording medium of the present technology is not particularly limited, but taking into account the configuration of the magnetic recording tape cartridge, for example, when a layer configuration in which a thick SUL layer is provided (for example, a layer configuration including an SUL layer with a film thickness of 50 nm or more) is adopted, the film thickness can be set to 4.50 μm or less, and when a layer configuration in which no SUL layer is provided or a layer configuration in which a thin SUL layer is provided (for example, a layer configuration including an SUL layer with a film thickness of 50 nm or less) is adopted, the film thickness can be set to 4.40 μm or less.

[0179] [Magnetic Recording Tape] The present technology provides a magnetic recording tape in the form of a long magnetic recording medium according to the present technology. This magnetic recording tape can be used for recording or playback via a magnetic head. As described above, the magnetic recording tape according to the present technology can effectively suppress a decrease in the abrasive power of the surface that comes into contact with the magnetic head, thereby effectively maintaining the function of removing dirt from the magnetic head.

[0180] There are no particular limitations on the magnetic head that can be used with the magnetic recording tape of the present technology, and recording or playback can be suitably performed using any magnetic head, such as a ring-type magnetic head, a tilt-type magnetic head, etc. Furthermore, there are no particular limitations on the running speed of the magnetic recording tape using the magnetic recording medium of the present technology when recording or playback via the magnetic head, and any running speed can be used.

[0181] [Magnetic Recording Tape Cartridge] The present technology also provides a magnetic recording tape cartridge (also referred to as a tape cartridge) including a magnetic recording tape using the magnetic recording medium of the present technology. In the magnetic recording tape cartridge, the magnetic recording medium may be configured, for example, to be wound around a reel and housed in a case (cartridge case). The magnetic recording tape cartridge may include, for example, a communication unit that communicates with a recording / playback device described below, a memory unit, and a control unit that stores information received from the recording / playback device via the communication unit in the memory unit, and reads information from the memory unit and transmits it to the recording / playback device via the communication unit in response to a request from the recording / playback device. The information may include adjustment information for adjusting the tension applied to the magnetic recording medium in the longitudinal direction.

[0182] An example of the configuration of a magnetic recording tape cartridge 10A equipped with a magnetic recording medium T having the above-described configuration will be described with reference to FIG.

[0183] 10 is an exploded perspective view showing an example of the configuration of a magnetic recording tape cartridge 10 A. The magnetic recording tape cartridge 10 A is a magnetic recording tape cartridge that conforms to 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 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 tape LT is connected to one end of the magnetic tape T. A leader pin 220 is provided at the tip of the leader tape LT.

[0184] The cartridge memory 211 is provided near one corner of the magnetic recording tape cartridge 10A. When the magnetic recording tape 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, described below, specifically with the reader / writer (not shown), using a wireless communication standard that complies with the LTO standard.

[0185] In the example of the magnetic recording tape cartridge shown in FIG. 10, an example is shown in which the magnetic recording tape is wound around one reel, but the number of reels may be multiple (for example, two).

[0186] [Recording / Reproducing Device] <Configuration of Recording / Reproducing Device> Fig. 11 is a diagram showing an example of the configuration of a recording / reproducing device using a magnetic recording tape cartridge according to the present technology. With reference to Fig. 11, an example of the configuration of a recording / reproducing device 30 that records and reproduces data on a magnetic recording medium 10 will be described.

[0187] The recording and reproducing device 30 has a configuration that allows adjustment of the tension applied in the longitudinal direction of the magnetic recording medium 10. The recording and reproducing device 30 also has a configuration that allows a magnetic recording tape cartridge 10A to be loaded into it. Here, for ease of explanation, a case will be described in which the recording and reproducing device 30 has a configuration that allows one magnetic recording tape cartridge 10A to be loaded into it, but the recording and reproducing device 30 may also have a configuration that allows multiple magnetic recording tape cartridges 10A to be loaded into it.

[0188] The recording and reproducing device 30 is preferably a timing servo type magnetic recording and reproducing device, and the magnetic recording medium of the present technology is suitable for use in a timing servo type magnetic recording and reproducing device.

[0189] The recording / reproducing device 30 is connected to information processing devices such as a server 41 and a personal computer (hereinafter referred to as "PC") 42 via a network 43, and is configured to be able to record data supplied from these information processing devices onto the magnetic recording tape cartridge 10A. The shortest recording wavelength of the recording / reproducing device 30 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.

[0190] As shown in Figure 11, the recording and playback device includes a spindle 31, a reel 32 on the recording and playback device side, a spindle drive device 33, a reel drive device 34, a plurality of guide rollers 35, a head unit 36, a communication interface (hereinafter referred to as I / F) 37, and a control device 38.

[0191] The spindle 31 is configured so that a magnetic recording tape cartridge 10A can be attached thereto. The magnetic recording tape cartridge 10A conforms to the LTO (Linear Tape Open) standard, and rotatably houses a single reel 10C around which a magnetic recording medium 10 is wound in a cartridge case 10B. A V-shaped servo pattern is pre-recorded as a servo signal on the magnetic recording medium 10. The reel 32 is configured so that the tip of the magnetic recording medium 10 pulled out from the magnetic recording tape cartridge 10A can be fixed.

[0192] The present technology also provides a magnetic recording tape cartridge including a magnetic recording medium according to the present technology, in which the magnetic recording medium may be wound on a reel, for example.

[0193] The spindle drive device 33 is a device that rotates the spindle 31. The reel drive device 34 is a device that rotates the reel 32. When recording or reproducing data on the magnetic recording medium 10, the spindle drive device 33 and the reel drive device 34 rotate the spindle 31 and the reel 32, thereby running the magnetic recording medium 10. The guide roller 35 is a roller that guides the running of the magnetic recording medium 10.

[0194] The head unit 36 ​​includes a plurality of recording heads for recording data signals on the magnetic recording medium 10, a plurality of reproducing heads for reproducing the data signals recorded on the magnetic recording medium 10, and a plurality of servo heads for reproducing the servo signals recorded on the magnetic recording medium 10. Any magnetic head can be used as the recording head, such as a ring-type head or a tilt-type magnetic head.

[0195] The communication I / F 37 is for communicating with information processing devices such as a server 41 and a PC 42 , and is connected to a network 43 .

[0196] The control device 38 controls the entire recording / reproducing device 30. For example, in response to a request from an information processing device such as a server 41 or a PC 42, the control device 38 records a data signal supplied from the information processing device onto the magnetic recording medium 10 using the head unit 36. In addition, in response to a request from the information processing device such as the server 41 or a PC 42, the control device 38 reproduces the data signal recorded on the magnetic recording medium 10 using the head unit 36, and supplies the reproduced data signal to the information processing device.

[0197] The control device 38 also detects changes in the width of the magnetic recording medium 10 based on the servo signals supplied from the head unit 36. Specifically, multiple V-shaped servo patterns are recorded on the magnetic recording medium 10 as servo signals, and the head unit 36 ​​simultaneously reproduces two different servo patterns using two servo heads on the head unit 36, thereby obtaining respective servo signals. Using relative position information between the servo patterns and the head unit obtained from these servo signals, the position of the head unit 36 ​​is controlled to track the servo patterns. At the same time, distance information between the servo patterns can be obtained by comparing the two servo signal waveforms. By comparing this distance information between the servo patterns obtained during each measurement, the change in the distance between the servo patterns at each measurement can be obtained. By taking into account the distance information between the servo patterns when the servo patterns were recorded, the change in the width of the magnetic recording medium 10 can also be calculated. The control device 38 controls the rotational drive of the spindle drive device 33 and the reel drive device 34 based on the change in the distance between the servo patterns obtained as described above or the calculated change in the width of the magnetic recording medium 10, and adjusts the tension in the longitudinal direction of the magnetic recording medium 10 so that the width of the magnetic recording medium 10 becomes a specified width or approximately a specified width. This makes it possible to suppress changes in the width of the magnetic recording medium 10.

[0198] <Operation of Recording / Reproducing Device> Next, we will explain the operation of the recording / reproducing device 30 having the above configuration. First, the magnetic recording tape cartridge 10A is loaded into the recording / reproducing device 30, the leading end of the magnetic recording medium 10 is pulled out and transported to the reel 32 via multiple guide rollers 35 and the head unit 36, and the leading end of the magnetic recording medium 10 is attached to the reel 32.

[0199] Next, when an operating unit (not shown) is operated, the spindle drive device 33 and the reel drive device 34 are driven under the control of the control device 38, and the spindle 31 and the reel 32 are rotated in the same direction so that the magnetic recording medium 10 runs from the reel 10C toward the reel 32. As a result, the magnetic recording medium 10 is wound onto the reel 32, while the head unit 36 ​​records information onto the magnetic recording medium 10 or reproduces information recorded on the magnetic recording medium 10.

[0200] When the magnetic recording medium 10 is rewound onto the reel 10C, the spindle 31 and the reel 32 are rotated in the opposite direction to that described above, causing the magnetic recording medium 10 to run from the reel 32 to the reel 10C. During this rewinding, the head unit 36 ​​also records information onto the magnetic recording medium 10 or reproduces information recorded on the magnetic recording medium 10.

[0201] The present technology can have the following configuration: [1] A substrate layer, a magnetic layer containing magnetic crystal particles, and a protective layer are laminated in this order, the protective layer contains DLC and H element, and when the surface of the protective layer is measured by Raman spectroscopy, the wavelength is 1000 to 1800 cm ―１a magnetic recording medium in which the baseline of the relative intensity of the Raman spectrum in a measurement region is defined by a linear function, the relative intensity of the Raman spectrum derived from the H element is defined as a value obtained by integrating the baseline, and the relative ratio of the relative intensity of the Raman spectrum derived from the H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region exceeds 0.32. [2] The magnetic recording medium according to [1], wherein the relative ratio of the relative intensity of the Raman spectrum derived from the H element is 0.38 or more. [3] The magnetic recording medium according to [1] or [2], wherein the relative ratio of the relative intensity of the Raman spectrum derived from the H element is 0.53 or less. [4] The magnetic recording medium according to [1] or [2], wherein the relative ratio of the relative intensity of the Raman spectrum derived from the H element is less than 0.50. [5] The magnetic recording medium according to any one of [1] to [4], wherein the counts per second of the elements constituting the magnetic crystal grains are 243 cps or less when secondary ion mass measurement is performed on the surface of the magnetic recording medium on which the protective layer is provided using a Ga liquid metal ion gun. [6] The magnetic recording medium according to [5], wherein the elements constituting the magnetic crystal grains are Co, Pt, or Cr. [7] The magnetic recording medium according to any one of [1] to [6], wherein the thickness of the magnetic recording medium is 4.50 μm or less. [8] The magnetic recording medium according to any one of [1] to [7], wherein the film thickness of the protective layer is 10.0 nm or less. [9] The magnetic recording medium according to any one of [1] to [8], wherein the protective layer has one or more H-element-added layers in which the relative ratio of the relative intensities of Raman spectra derived from the H element exceeds 0.32, and one or more H-element-unadded layers in which the relative ratio of the relative intensities of Raman spectra derived from the H element does not exceed 0.32.

[10] The magnetic recording medium according to [9], wherein the film thickness of the H element-added layer is 3.0 nm or less.

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

[10] , wherein the protective layer has a lubricant layer containing a lubricant.

[12] The magnetic recording medium according to

[11] , wherein the lubricant contains a compound having a fluorine hydrocarbon group.

[13] The surface of the lubricant layer is treated with a 3.0 × 10 ―６

[12] The magnetic recording medium according to

[12] , wherein the counts per second of a peak corresponding to a fluorine 1s orbital are 32 kcps or less when measured by X-ray photoelectron spectroscopy at a setting of 6 kV / 20 mA at a pressure of 100 Pa or less.

[14] The magnetic recording medium according to

[13] , wherein the counts per second of a peak corresponding to a fluorine 1s orbital are 28 kcps or more.

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

[14] , wherein a seed layer is provided between the substrate layer and the magnetic layer.

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

[15] , wherein a back layer is provided on the surface of the substrate layer opposite to the surface facing the magnetic layer.

[17] A magnetic recording tape cartridge having a configuration in which a magnetic recording tape using the magnetic recording medium according to any one of [1] to

[16] is wound around a reel and housed in a case.

[18] A method for manufacturing a magnetic recording medium, comprising: forming a protective layer by sputtering carbon element on the surface of a magnetic recording medium having a laminated structure with a base layer and a magnetic layer containing magnetic crystal grains, the surface being on the side of the magnetic layer; and performing the sputtering in an atmosphere of an inert gas to which a gas consisting of a compound containing an H element has been added.

[19] A method for manufacturing a magnetic recording medium according to

[18] , wherein the gas consisting of a compound containing an H element is a hydrocarbon gas.

[20] A method for manufacturing a magnetic recording medium according to

[19] , wherein the hydrocarbon gas is ethylene.

[0202] The present technology will be described in more detail below using examples, but the present technology is not limited to the contents of the examples shown below.

[0203] <Production of Magnetic Recording Medium> [Production of Comparative Magnetic Recording Medium] First, a comparative magnetic recording medium (Comparative Example 1) was produced under the following conditions: The film thickness (average thickness) of each layer was confirmed by the method described in this specification.

[0204] (Step of forming second seed layer) Under the following film forming conditions, (TiCr) ９８ O ２A second seed layer having an average thickness of 2.0 nm and consisting of the above was formed on the first main surface of a long polymer film (substrate / base material layer). The polymer film used was an aramid film having a thickness of 3.8 μm. Sputtering method: DC magnetron sputtering method Target: Ti ５０ Cr ５０ Target gas type: Ar Gas pressure: 0.5 Pa Input power: 21.5 mW / mm ２ Feed speed: 4 m / min

[0205] (Step of forming first seed layer) Next, Ni was formed under the following film forming conditions. ９４ W ６ A first seed layer having an average thickness of 10.0 nm and consisting of: ９４ W ６ Target gas type: Ar Gas pressure: 0.3 Pa Input power: 47 mW / mm ２ Feed speed: 4 m / min

[0206] (Step of forming second underlayer) Next, a second underlayer made of Ru and having an average thickness of 5.0 nm was formed on the first seed layer under the following film formation conditions: Sputtering method: DC magnetron sputtering method Target: Ru target Gas type: Ar Gas pressure: 0.3 Pa Input power: 24 mW / mm ２ Feed speed: 4 m / min

[0207] (Step of forming first underlayer) Next, a first underlayer made of Ru and having an average thickness of 18.0 nm was formed on the second underlayer under the following film formation conditions: Sputtering method: DC magnetron sputtering method Target: Ru target Gas type: Ar Gas pressure: 13.0 Pa Input power: 90 mW / mm ２ Feed speed: 4 m / min

[0208] (Magnetic Layer Forming Process) Next, a recording layer made of (CoPtCr)-(SiO) and having an average thickness of 14.0 nm was formed on the first underlayer under the following film forming conditions: Film forming method: DC magnetron sputtering method Target: Co ４７．２ Pt１５．２ Cr １３．７ Si ６．６ O １７．２ Target gas type: Ar Gas pressure: 6.0 Pa Input power: 90 mW / mm ２ Feed speed: 4 m / min

[0209] (CAP layer formation process) Next, Co was formed under the following film formation conditions. ６５ Cr ７．５ Pt ２０ B ７．５ A CAP layer having an average thickness of 3.0 nm and consisting of the above was formed on the magnetic layer. Sputtering method: DC magnetron sputtering method Target: Co ６５ Cr ７．５ Pt ２０ B ７．５ Target gas type: Ar Gas pressure: 1.5 Pa Input power: 5.25 mW / mm ２ Feed speed: 4 m / min

[0210] (Protective Layer Forming Process) Next, under the following film forming conditions, a protective layer made of carbon and having an average thickness of 5.0 nm was formed on the recording layer. The protective layer was formed using an apparatus equipped with two sputtering chambers (No. 1 cathode and No. 2 cathode in FIG. 12) capable of adding gases other than inert gas, as shown in FIG. 12, with each chamber forming a 2.5 nm thick protective layer, thereby forming a 5.0 nm thick protective layer. Here, as shown in FIG. 13, the lower layer of the protective layer of the magnetic recording medium (the layer of the protective layer on the magnetic layer side) was formed by the No. 1 cathode, and the upper layer of the protective layer of the magnetic recording medium was formed by the No. 2 cathode. Among the examples shown in FIG. 13, <13A> is an image of the protective layer formed in the magnetic recording medium for comparison. Film formation method: DC magnetron sputtering method Target: carbon target Gas type: Ar Gas pressure: 0.8 Pa Input power: 90 mW / mm ２ x 2 cathodes Feed speed: 6 m / min

[0211] (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 mass % of a perfluoroalkyl carboxylic acid ester and 0.06 mass % of a fluoroalkyl dicarboxylic acid derivative in a general-purpose solvent.

[0212] (Backcoat Layer Formation Process) Next, a coating material for forming a back layer was applied to a second main surface of the polymer film as the base layer, opposite to the first main surface, and then dried to form a back layer. More specifically, a back layer was formed with an average thickness of 0.3 μm, which was composed of non-magnetic powder composed of carbon and calcium carbonate and a polyurethane binder.

[0213] [Manufacturing of Magnetic Recording Media According to the Present Technology] (Examples 1-3) Among the manufacturing conditions for the magnetic recording media for comparison (Comparative Example 1), the film forming conditions for the protective layer were changed to a condition in which ethylene (C) was used as a compound containing H element in Ar, which was an inert gas. ２ H ４ The magnetic recording media according to Examples 1 to 3 were manufactured under the conditions shown in Table 1. The other conditions were the same as those used for manufacturing the comparative magnetic recording media.

[0214]

[0215] In the examples shown in Figure 13, <13B> is an image of the protective layer formed in the magnetic recording medium of Examples 1 and 2, and <13C> is an image of the protective layer formed in the magnetic recording medium of Example 3.

[0216] Example 4 Next, a sputtering target used for forming the magnetic layer was Co. ４７．８ Pt １５．４ Cr １３．９ Si ６．７ O １６．２ A magnetic recording medium of Example 4 was manufactured under the same conditions as in Example 1, except that the target was used.

[0217] (Examples 11-14) Next, to confirm that similar effects can be obtained even when another layer is added between the protective layer and the substrate layer of the magnetic recording medium according to the present technology, magnetic recording media provided with an SUL layer (soft magnetic underlayer) were manufactured. These magnetic recording media were manufactured under the same conditions as in Example 1, except that an SUL layer was formed and the film thickness of the magnetic layer was changed.

[0218] (SUL Layer Forming Process) The SUL layer of the magnetic recording media of Examples 11-14 was formed on the first main surface of the polymer film for the base layer using the sputtering target shown in Table 2, before forming the second seed layer, to a thickness shown in Table 2. The film formation conditions are shown below. In the magnetic recording media of Examples 11-14, the second seed layer was formed on the SUL layer. Furthermore, the magnetic recording media of Examples 11-14 were manufactured by changing the thickness of the magnetic layer to the thickness shown in Table 2.

[0219] Sputtering method: DC magnetron sputtering method Gas type: Ar Gas pressure: 0.5 Pa Input power: 153 mW / mm ２ Feed speed: 4 m / min

[0220]

[0221] (Examples 15 to 18) Next, for the magnetic recording media of Examples 14 to 18, the sputtering target used for forming the magnetic layer was Co. ４７．８ Pt １５．４ Cr １３．９ Si ６．７ O １６．２ The target was manufactured under the conditions shown in Table 3. The other conditions were the same as those in Example 11.

[0222]

[0223] <Cutting Step> The magnetic recording media of Examples 1 to 4, Examples 11 to 18, and Comparative Example 1 obtained as described above were cut into 1 / 2 inch (12.65 mm) widths. This resulted in long magnetic recording tapes.

[0224] The obtained 1 / 2-inch wide magnetic recording tapes were wound onto reels provided inside cartridge cases to obtain magnetic recording tape cartridges. Servo signals were recorded on the magnetic recording tapes using a servo track writer. The servo signals consisted of a series of V-shaped magnetic patterns, and the magnetic patterns were recorded in advance in two or more rows parallel to each other in the longitudinal direction, with known intervals between each other.

[0225] [Evaluation of the protective layer according to the present technology] Of the magnetic recording media obtained above, the effects of the protective layer according to the present technology were confirmed by carrying out the evaluations described below using the magnetic recording media and magnetic recording tape cartridges of Examples 1 to 3 and Comparative Example 1. The results of the evaluations for each magnetic recording medium are shown in Table 4.

[0226] <Measurement by Raman Spectroscopy> Each magnetic recording tape was attached to a φ6 mm sample stage to serve as a measurement sample, and measurement was performed by Raman spectroscopy in an environment of 23°C and 50% humidity using a DXR Raman microscope manufactured by Thermo Scientific Corp. The measurement conditions are shown below.

[0227] Objective lens × 50 Laser wavelength: 532 nm Laser output: 0.3 mW Aperture: 50 μm Measurement exposure time: 30 seconds, Number of exposures: 10 times

[0228] Using the obtained Raman spectroscopy measurement results, ―１ The baseline of the relative intensity of the Raman spectrum in the measurement region was defined by a linear function, and the value obtained by integrating the baseline was taken as the relative intensity of the Raman spectrum derived from the H element. ―１ The relative ratio of the relative intensity of the Raman spectrum attributable to H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region was calculated.

[0229] For each magnetic recording medium, the calculated relative intensity of the Raman spectrum derived from H element and the relative ratio of the relative intensity of the Raman spectrum derived from H element to the total peak area of ​​the relative intensity of the Raman spectrum in the measurement region are shown in Table 4. From the obtained results, it can be confirmed that by increasing the ratio of ethylene added to the inert gas, the relative intensity of the Raman spectrum derived from H element increases, and the content of H element in the protective layer tends to increase.

[0230] <Secondary ion mass measurement / evaluation of magnetic layer coverage> For each magnetic recording tape, a 1 cm square piece of magnetic recording tape was attached to a dedicated sample stage to serve as a measurement sample, and secondary ion mass measurement was performed using a Ga liquid metal ion gun with a TOF-SIMS IV manufactured by IONTOF Corp. The measurement conditions are shown below.

[0231] Measurement mode: High current bunching mode (25 kV) High mass resolution mode DC ion current: 25 nA DC or higher Pulse width: 700 ps or less Mass resolution: 8000 (M / ΔM) (29 amu) Pulse ion current: 2.5 pA at 10 kHz (1560 ions / pulse) Beam diameter: 10 μm or less

[0232] The counts per second of the Co element were calculated from the peak intensity of the Co element measured in positive mode. The calculated counts per second of the Co element for each magnetic recording medium are shown in Table 4. From the obtained results, it can be confirmed that increasing the ratio of ethylene added to the inert gas improves the coverage of the magnetic layer. It can also be confirmed that the effect of improving the coverage of the magnetic layer can be obtained whether the H element is contained in the upper or lower layer of the protective layer. In particular, when the H element is contained in the upper layer side of the protective layer, the effect of improving the coverage of the magnetic layer can be obtained more efficiently.

[0233] 14 is a graph comparing the number of Co element counts per second for the magnetic recording media of Examples 1 and 2 and Comparative Example 1. From the right, the graph shows Example 2, Example 1, and Comparative Example 1, which contain a high ethylene content, respectively, and no ethylene added. It can be seen that the coverage of the magnetic layer improves as the proportion of ethylene added to the inert gas increases.

[0234] 15 is a graph showing the change in the number of counts per second of Co elements when secondary ion mass measurement is performed using a Ga liquid metal ion gun, with the thickness of the protective layer being changed according to the present technology. It can be seen that, within the range of protective layer thicknesses up to 10 nm, the number of counts per second of Co elements decreases as the thickness of the protective layer increases, and the coverage rate of the magnetic layer improves.

[0235] <Abrasive Force Measurement> The abrasiveness of each magnetic recording tape was measured under the following conditions and was taken as the abrasive force of each magnetic recording tape.

[0236] (Wear Volume of Abrasivity Bar) The wear volume of the abrasivity bar is measured in accordance with ECMA-319 Annex C. Note that the abrasivity is measured by changing the ceramic material of the abrasivity bar to AlFeSi. Abrasivity is an index that indicates the degree of wear of the magnetic head by the magnetic surface of the magnetic recording tape when the magnetic recording tape comes into contact with the magnetic head and runs. For example, a square prism bar (abrasivity bar) A made of a ceramic material (AlFeSi) shown in FIG. 17 was set in a dedicated jig (a jig described in ECMA-319 Appendix C) shown in FIG. 16 , and attached to a magnetic head unit such as a tape drive so that the corners of the square prism came into contact with the magnetic recording tape. A 30 m long magnetic recording tape was run 1,000 times at a wrap angle of 12°, a tension of 1.0 N±0.1 N, and a tape speed of 3.0 m / s. After the run, the width B of the worn abrasive bar was measured as shown in FIG. 18 . Using the measurement results of the width B, the wear volume of the abrasive bar was calculated using the aforementioned equation (11). The results are shown in Table 4.

[0237] From the results obtained, it was found that adding ethylene to the inert gas reduces the abrasive power of the tape while ensuring cleaning power to remove dirt from the magnetic head. 3 ] and it can be confirmed that it can be adjusted more than this.

[0238] <Measurement by X-ray photoelectron spectroscopy / lubricant amount measurement> Each magnetic recording tape was attached to a φ6 mm sample stage to serve as a measurement sample. The surface of the lubricant layer of the magnetic recording tape was measured using an ESCA-3400 manufactured by Shimadzu Corporation. ―６ At a pressure of 6 kV / 20 mA or less, a peak corresponding to the 1s orbital of fluorine was detected by X-ray photoelectron spectroscopy.

[0239] The peak intensity area of ​​the peak corresponding to the fluorine 1s orbital detected above was normalized by the peak intensity area corresponding to the Au 4f orbital measured on the same day, to calculate the number of counts per second of the peak corresponding to the fluorine 1s orbital. The evaluation results for each magnetic recording medium are shown in Table 4.

[0240] Each peak was detected in the following range: (Au 4f): Peak intensity area in the range of binding energy Start: 94, End: 81 (eV) (F 1s): Peak intensity area in the range of binding energy Start: 696, End: 684 (eV)

[0241]

[0242] Next, the magnetic recording tape according to the magnetic recording medium of Example 2 was used to measure the effect on the amount of lubricant when the wear volume of the abrasive bar was increased by increasing the number of repeated runs. The measurement conditions for the wear volume of the abrasive bar and the amount of lubricant were the same as those for the above-mentioned measurements. The evaluation results are shown in Table 5.

[0243]

[0244] [Confirmation of the effect of the protective layer on magnetic recording media with other layer configurations] The same measurements as above were carried out in Example 4, in which the components of the magnetic layer were changed. As a result, it was found that by increasing the ratio of ethylene added to the inert gas, the content of H element in the protective layer increased, the coverage of the magnetic layer improved, and the abrasive power of the tape was reduced while the cleaning power for removing dirt from the magnetic head was secured at 1.8E05 [μm 3 ] and it was confirmed that it is possible to adjust it more than this.

[0245] Similarly, in Examples 11 to 18, which are examples in which a layer (in this case, an SUL layer) was added between the protective layer and the substrate layer, the components of the layer (in this case, the SUL layer) provided between the protective layer and the substrate layer were changed, and the film thickness of the magnetic layer provided between the protective layer and the substrate layer was changed, the same measurements as described above were performed, and it was confirmed that the effects of the protective layer according to the present technology could be obtained similarly to the above cases. These results suggest that, regardless of the conditions such as the layer configuration, film thickness, and components provided between the protective layer and the substrate layer of the magnetic recording medium, by adding H element to the protective layer containing DLC ​​of the magnetic recording medium, it is possible to ensure the cleaning power for removing dirt from the magnetic head during running of the magnetic recording medium while adjusting to a range in which deterioration of the magnetic head can be suppressed.

[0246] T, T2, T3, T4, T5: magnetic recording medium L: lubricant layer P: protective layer C: CAP layer 1: magnetic layer (recording layer) 2: intermediate layer 3: underlayer 31: first underlayer 32: second underlayer 4: seed layer 41: first seed layer 42: second seed layer 5: substrate layer (base layer) 6: back layer 7: SUL layer (soft magnetic underlayer) 10A magnetic recording tape cartridge T magnetic recording medium (magnetic recording tape) 30 recording / reproducing device

Claims

1. A substrate layer, a magnetic layer containing magnetic crystal particles, and a protective layer are laminated in this order, and the protective layer contains DLC and H element. When the surface of the protective layer is measured by Raman spectroscopy, the wave number is 1000 to 1800 cm ―１ a baseline of the relative intensity of the Raman spectrum in a measurement region is defined by a linear function, the relative intensity of the Raman spectrum derived from the H element is defined as a value obtained by integrating the baseline, and a relative ratio of the relative intensity of the Raman spectrum derived from the H element to a total peak area of ​​the relative intensity of the Raman spectrum in the measurement region exceeds 0.

32.

2. The magnetic recording medium according to claim 1, wherein the relative ratio of the relative intensities of the Raman spectra originating from the H element is 0.38 or more.

3. The magnetic recording medium according to claim 1, wherein the relative ratio of the relative intensities of the Raman spectra originating from the H element is 0.53 or less.

4. The magnetic recording medium according to claim 1, wherein the relative ratio of the relative intensities of the Raman spectra originating from the H element is less than 0.

50.

5. A magnetic recording medium as described in claim 1, wherein when secondary ion mass measurement is performed on the surface of the magnetic recording medium on which the protective layer is provided using a Ga liquid metal ion gun, the number of counts per second of the elements constituting the magnetic crystal grains is 243 cps or less.

6. The magnetic recording medium according to claim 5, wherein the element constituting the magnetic crystal grains is one of Co, Pt, and Cr.

7. The magnetic recording medium according to claim 1, wherein the thickness of the magnetic recording medium is 4.50 μm or less.

8. The magnetic recording medium according to claim 1, wherein the protective layer has a thickness of 10.0 nm or less.

9. The magnetic recording medium according to claim 1, wherein the protective layer comprises one or more H-element-added layers in which the relative ratio of the relative intensities of the Raman spectra derived from the H element exceeds 0.32, and one or more H-element-unadded layers in which the relative ratio of the relative intensities of the Raman spectra derived from the H element does not exceed 0.

32.

10. The magnetic recording medium according to claim 9, wherein the film thickness of the H-element-added layer is 3.0 nm or less.

11. The magnetic recording medium according to claim 1, further comprising a lubricant layer containing a lubricant on the outside of said protective layer.

12. The magnetic recording medium according to claim 11, wherein the lubricant comprises a compound having a fluorine-containing hydrocarbon group.

13. The surface of the lubricant layer is polished with 3.0 x 10 ―６ 13. The magnetic recording medium according to claim 12, wherein when measured by X-ray photoelectron spectroscopy at a setting of 6 kV / 20 mA at a pressure of 100 Pa or less, the counts per second of a peak corresponding to a fluorine 1s orbital are 32 kcps or less.

14. The magnetic recording medium according to claim 13, wherein the number of counts per second of the peak corresponding to the fluorine 1s orbital is 28 kcps or more.

15. The magnetic recording medium according to claim 1, further comprising a seed layer between the substrate layer and the magnetic layer.

16. The magnetic recording medium according to claim 1, further comprising a back layer on the surface of said substrate layer opposite to the surface facing said magnetic layer.

17. A magnetic recording tape cartridge in which a magnetic recording tape using the magnetic recording medium according to claim 1 is wound around a reel and housed in a case.

18. A method for manufacturing a magnetic recording medium, comprising: forming a protective layer on the surface of a magnetic recording medium having a laminated structure with a base layer and a magnetic layer containing magnetic crystal grains by sputtering carbon elements on the surface of the magnetic layer side; and carrying out the sputtering in an atmosphere of an inert gas to which a gas consisting of a compound containing H elements has been added.

19. The method for producing a magnetic recording medium according to claim 18, wherein the gas comprising a compound containing H element is a hydrocarbon gas.

20. The method for producing a magnetic recording medium according to claim 19, wherein the hydrocarbon gas is ethylene.

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