Heat assisted magnetic recording (HAMR) media with an optically coupled multilayer between the recording layer and the heat sink layer

Abstract

A heat assisted magnetic recording (HAMR) disc has a magnetic recording layer (typically a FePt chemically ordered alloy), a seed-thermal barrier layer (typically MgO) below the recording layer, a heat sink layer, and an optical coupling multilayer of alternating plasmonic and non-plasmonic materials between the heat sink layer and the seed-thermal barrier layer. Unlike the heat sink layer, the multilayer has very low in-plane and out-of-plane thermal conductivity, and thus does not function as a heat sink. The low thermal conductivity of the multilayer also allows the multilayer to function as a thermal barrier. Due to the plasmonic materials in the multilayer, the multilayer provides excellent optical coupling to the near field transducer (NFT) of the HAMR disc drive.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Nonprovisional Application No. 17 / 395,820, filed August 6, 2021, entitled "HEAT-ASSISTED MAGNETIC RECORDING (HAMR) MEDIUM WITH OPTICAL-COUPLING MULTILAYER BETWEEN THE RECORDING LAYER AND HEAT-SINK LAYER", the entire contents of which are incorporated herein by reference for all purposes. Background Technology Technical Field

[0003] The present invention relates generally to a perpendicular magnetic recording medium for use as a heat-assisted magnetic recording (HAMR) medium, and more specifically, to an HAMR medium having improved optical and thermal properties.

[0004] Description of related fields

[0005] In conventional continuous-particle magnetic recording media, the magnetic recording layer is a continuous layer of granular magnetic material covering the entire surface of the disk. In magnetic recording disk drives, the magnetic material (or medium) used for the recording layer on the disk is selected to have sufficient coercivity to ensure that the magnetized data region defining the data "bit" is precisely written and remains magnetized until overwritten by a new data bit. As the areal data density (the number of bits that can be recorded per unit surface area of ​​the disk) increases, the magnetic grains constituting the data bit can become so small that they can be easily demagnetized by thermal instabilities or agitation within the magnetized bit (the so-called "superparamagnetic" effect). To avoid thermal instabilities in the stored magnetization, high magnetocrystalline anisotropy (K0) is required. u The medium. The thermal stability of magnetic grains is largely determined by K. u V is determined, where V is the volume of the magnetic grain. Therefore, a high K u The recording layer is important for thermal stability. However, increasing K... u It also increases the coercivity of the medium, which can exceed the write field capability of the write head.

[0006] Since the coercivity of the magnetic materials used in recording layers is known to be temperature-dependent, one proposed solution to the thermal stability problem is heat-assisted magnetic recording (HAMR). In this system, the magnetic recording material is locally heated during writing to reduce the coercivity sufficiently for writing, while maintaining a coercivity / anisotropy high enough to achieve thermal stability of the recorded bits within the ambient temperature range of the disk drive (i.e., the normal operating temperature range of approximately 15°C–60°C). In some proposed HAMR systems, the magnetic recording material is heated to near or above its Curie temperature. The recorded data is then read back at ambient temperature using a conventional magnetoresistive read head.

[0007] The most common type of proposed HAMR disk drive uses a laser source and optical waveguides, along with a near-field transducer (NFT). A "near-field" transducer refers to a "near-field optics" device where light passes through an element with subwavelength characteristics and is coupled to a second element located at a subwavelength distance from the first element, such as a substrate like a magnetic recording medium. The NFT is typically located at the gas bearing surface (GBS) of a gas bearing slider, which also supports the read / write head and straddles or "archives" above the disk surface.

[0008] A type of high K-type magnetic anisotropy proposed with perpendicular magnetic anisotropy u HAMR media are chemically ordered FePt (or CoPt) alloys in the L10 phase. The bulk chemically ordered FePt alloy is called a face-centered tetragonal (FCT) L10 ordered phase material (also known as CuAu material). The c-axis of the L10 phase is the easy magnetization axis and is perpendicular to the disk substrate orientation. To obtain the desired chemical order of the L10 phase, the FePt alloy needs to be annealed after deposition or deposited while the substrate is kept at a high temperature (e.g., approximately 500°C to 700°C).

[0009] The magnetic layer of FePt alloys typically also includes separators formed between FePt grains, such as C, SiO2, TiO2, and TaO, which reduce grain size. x Materials such as ZrO2, SiC, SiN, TiC, TiN, B, BC, or BN are used. In HAMR media, a seed-thermal barrier layer such as MgO is used to induce the desired (001) texture of FePt magnetic grains and influence their geometric microstructure, and also acts as a thermal barrier layer so that heat from the NFT does not dissipate too quickly from the FePt recording layer. A heat dissipation layer is located below the seed-thermal barrier layer to move heat first laterally (in-plane) and then vertically (i.e., in the out-of-plane direction of the recording layer) downwards to the substrate, thus resulting in less lateral heat diffusion in the recording layer. Summary of the Invention

[0010] The heat dissipation layer, selected from Au, Ag, and Cu, provides excellent thermal and optical properties for the HAMR medium. The high lateral (in-plane) thermal conductivity of Au, Ag, and Cu allows heat to move laterally first and then very rapidly vertically downwards to the substrate. Furthermore, Au, Ag, and Cu are plasmonic materials. One definition of a plasmonic material is a metal or metal alloy whose extinction coefficient k at the wavelength of interest is at least twice the refractive index n. Therefore, plasmonic materials also provide excellent optical coupling with NFTs, which generate confined heat sources in the recording layer.

[0011] However, directly bonding thick Au, Ag, and Cu plasmonic layers beneath a seed-thermal barrier layer (typically MgO) is challenging. The recording layer requires the correct grain structure and crystal orientation to achieve the desired magnetic properties. The recording layer is typically made of FePt L10 grains separated by thin oxide / nitride separation materials and requires a high-temperature deposition process. The recording layer also needs to have a uniform thickness and be very smooth, allowing the slider to remain only a few nanometers above the disk surface. However, Au, Ag, and Cu films become significantly rougher at high temperatures and are prone to interdiffusion upon heating. Therefore, an intermediate layer is needed between the Au, Ag, or Cu heat dissipation layer and the seed-thermal barrier layer. However, separating the heat dissipation layer and the recording layer by too large a distance is detrimental to the thermal and optical properties of the medium. For example, the optical benefits of plasmonic Au, Ag, and Cu are lost when used beneath an intermediate layer 10 nm to 25 nm thick.

[0012] In an embodiment of the invention, an optically coupled multilayer of alternating plasmonic and non-platinum materials is located between a seed-thermal barrier layer and a heat dissipation layer, without the need for an intermediate layer. Alternatively, the multilayer may be located within the seed-thermal barrier layer. Unlike the heat dissipation layer, this multilayer has very low in-plane and out-of-plane thermal conductivity, and therefore does not function as a heat dissipation layer. For this reason, a separate heat dissipation material layer is required below the multilayer. The low thermal conductivity of the multilayer also allows it to function as a thermal barrier. Due to the plasmonic materials in the multilayer, it provides excellent optical coupling with NFTs. Due to lamination, the multilayer provides good stability during annealing.

[0013] Importantly, HAMR media exhibit a high thermal gradient (TG) within the recording layer, meaning a sharp temperature drop exists at the edges of the bits being recorded. Similarly, the laser power (LP) required to achieve an acceptable thermal gradient, which is primarily determined by the optical and thermal properties of the layer beneath the recording layer, should be minimized to extend the lifetime of the NFT. The optically coupled multilayer in this embodiment improves the TG / LP ratio of HAMR media without a single plasmon layer.

[0014] To gain a more complete understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0015] Figure 1 is a top view of a heat-assisted magnetic recording (HAMR) disk drive according to the prior art.

[0016] Figure 2 depicts a cross-sectional view of a gas bearing slider and a portion of the HAMR disk used in a HAMR disk drive according to the prior art. The cross-sectional view is not drawn to scale because it is difficult to show very small features.

[0017] Figure 3 is a cross-sectional view of a HAMR disk having a single plasmonic heat dissipation layer of Au, Ag or Cu according to the prior art.

[0018] Figure 4 This is a cross-sectional view showing a HAMR disk according to an embodiment of the present invention.

[0019] Figure 5 This is a cross-sectional view showing a HAMR disk according to another embodiment of the present invention.

[0020] Figure 6 This refers to the in-plane thermal conductivity (TC) measured for RuAl / Au and RuAl / Rh multilayers with various thicknesses and alternating layer repetition numbers. IP The surface of the multilayer is formed on a glass substrate, with a thin 2nm Au or Rh capping to prevent oxidation of the multilayer.

[0021] Figure 7 Graphical data of thermal gradient / laser power (TG / LP) from computer-modeled RuAl(1nm) / Au(1nm) multilayers of various thicknesses are shown in contrast to single Au plasmonic layers of various thicknesses.

[0022] Figure 8 Graphical data of TG / LP from computer-modeled RuAl(1nm) / Rh(1nm) multilayers of various thicknesses are shown in contrast to single Au plasmonic layers of various thicknesses. Detailed Implementation

[0023] Figure 1 is a top view of a heat-assisted magnetic recording (HAMR) disk drive 100 according to the prior art. In Figure 1, the HAMR disk drive 100 is shown as a disk 200 having a continuous magnetic recording layer 31 with concentric circular data tracks 118. Only a portion of several representative tracks 118 near the inner and outer diameters of the disk 200 is shown.

[0024] The driver 100 has a housing or base 112 supporting the actuator 130 and a drive motor for rotating the magnetic recording disk 200. The actuator 130 may be a voice coil motor (VCM) rotary actuator with a rigid arm 131 that rotates about a pivot 132 (as shown by arrow 133). The head suspension assembly includes a suspension 135 and a head carrier such as a gas bearing slider 120, the suspension having one end attached to the end of the actuator arm 131 and the head carrier attached to the other end of the suspension 135. The suspension 135 allows the slider 120 to remain very close to the surface of the disk 200 and allows it to “tilt” and “roll” on a gas (typically air or helium) bearing generated by the disk as the disk 200 rotates in the direction of arrow 20. The slider 120 supports a HAMR head (not shown) that includes a magnetoresistive read head, an inductive write head, a near-field transducer (NFT), and an optical waveguide. For example, a semiconductor laser 90 with a wavelength of 780 to 980 nm can be used as a HAMR light source and is described as being supported on top of the slider 120. Alternatively, the laser can be located on a suspension 135 and coupled to the slider 120 via an optical channel. As the disk 200 rotates in the direction of arrow 20, the movement of the actuator 130 allows the HAMR head on the slider 120 to access different data tracks 118 on the disk 200. The slider 120 is typically formed of a composite material, such as an alumina / titanium carbide (Al2O3 / TiC) composite. Only one disk surface with an associated slider and read / write head is shown in Figure 1, but typically multiple disks are stacked on a hub rotated by a spindle motor, with individual sliders and HAMR heads associated with each surface of each disk.

[0025] In the following figures, the X direction represents the direction perpendicular to the gas bearing surface (GBS) of the slider, the Y direction represents the track width or cross-track direction, and the Z direction represents the direction along the track. Figure 2 is a schematic cross-sectional view showing an example of a HAMR head according to the prior art, which can also be used as the HAMR head in the embodiments of the present invention. In Figure 2, disk 200 is shown as a conventional disk, wherein the HAMR recording layer 31 is a continuous unpatterned magnetic recording layer of magnetizable material having magnetized regions or “bits” 34. Bits 34 are physically adjacent to each other, and the boundary between adjacent bits is called a magnetic transition 37. These bits are recorded in various data sectors. The recording layer 31 is typically made of a high anisotropy (K0) material with perpendicular magnetic anisotropy. u The disk is formed of a substantially chemically ordered FePt alloy (or CoPt alloy). The disk includes an outer coating 36, typically formed of amorphous diamond-like carbon (DLC), and a liquid lubricant layer 38, typically bonded perfluoropolyether (PFPE).

[0026] The gas bearing slider 120 is supported by a suspension 135. The slider 120 has a surface 122 facing the recording layer, on which an outer coating 124 is deposited. The outer coating 124 is typically a DLC outer coating with a thickness of approximately 10 to [missing value]. Within the range, and its outer surface forms the GBS of slider 120. Optional adhesive film or inner coating (not shown) such as to Silicon nitride (SiN) x The film can be deposited on surface 122 prior to the deposition of outer coating 124. Slider 120 supports magnetic write head 50, magnetoresistive (MR) read head 60, and flux read head shields S1 and S2. The recording magnetic field is generated by write head 50, which consists of coil 56, main magnetic pole 53 for transmitting the flux generated by coil 56, write pole 55 with end 52, and return pole 54. The magnetic field generated by coil 56 is transmitted through magnetic pole 53 to write end 52 located near optical near-field transducer (NFT) 74. Write head 50 is typically capable of operating at different clock rates to enable writing data at different frequencies. When light from waveguide 73 is incident, NFT 74, also known as plasmonic antenna, typically uses a low-loss metal (e.g., Au, Ag, Al, or Cu) shaped such that surface charge movement is concentrated at the tip located at slider GBS. The oscillating tip charge generates a strong near-field pattern, thereby heating recording layer 31. The metallic structure of NFT 74 can generate resonant charge movement (surface plasmons) to further enhance the strength and heating of the recording layer 31. At the moment of recording, the recording layer 31 of the disk 200 is heated by the optical near field generated by NFT 74, and simultaneously, the region or "bit" 34 is magnetized and thus written onto the recording layer 31 by applying a recording magnetic field generated by the write end portion 52.

[0027] A semiconductor laser 90 is mounted to the top surface of a slider 120. An optical waveguide 73 for guiding light from the laser 90 to the NFT 74 is formed within the slider 120. The laser 90 is typically capable of operating at different power levels. Materials ensuring that the refractive index of the waveguide 73 core material is greater than that of the cladding material can be used for the waveguide 73. For example, Al2O3 can be used as the cladding material, and TiO2, Ta2O5, and SiO2 are also suitable. x N y It can be used as a core material. Alternatively, SiO2 can be used as a coating material, and Ta2O5, TiO2, and SiO2 can also be used. x N y Alternatively, Ge-doped SiO2 may be used as the core material. The waveguide 73 that transmits light to the NFT 74 is preferably a single-mode waveguide.

[0028] Figure 3 is a cross-sectional view of a HAMR disk 200 having a continuous grain recording layer (RL) 31 according to the prior art. The recording layer 31 may be composed of a substantially chemically ordered FePt alloy (or CoPt alloy) with or without cleavage, as proposed in the prior art. The disk 200 is a substrate 201 having a generally flat surface, on which representative layers are typically deposited sequentially by sputtering. The disk substrate 201 may be any commercially available high-temperature glass substrate, but may also be an alternative substrate, such as silicon or silicon carbide. An adhesion layer 202, typically an amorphous adhesion layer material of about 10-200 nm, such as a CrTa or NiTa alloy, is deposited on the substrate 201.

[0029] An optional soft-walled layer (SUL) 204 of magnetically permeable material may be formed on the adhesion layer 202, which acts as a flux return path for the magnetic flux from the write head. The SUL 204 may be formed from magnetically permeable materials such as CoFeZr and certain alloys of CoZr, which are also compatible with the high-temperature deposition process of FePt. The SUL 204 may also be a laminate or multilayer SUL formed from multiple soft magnetic films separated by conductive films such as Al or CoCr. The SUL 204 may also be a laminate or multilayer SUL formed from multiple soft magnetic films separated by interlayer films mediating antiferromagnetic coupling, such as Ru, Ir, or Cr or their alloys. The SUL 204 may have a thickness in the range of approximately 5 nm to 100 nm.

[0030] A seed layer 205, such as a RuAl or NiAl layer, is deposited on the SUL 204, or, if the SUL is not used, on the adhesion layer 202. A heat dissipation layer 206 is then deposited on the seed layer 205. The heat dissipation layer 206 facilitates heat transfer from the RL to prevent heat diffusion into RL regions adjacent to the area where data is to be written, thereby preventing data rewriting in adjacent data tracks. The heat dissipation layer 206 can be formed of plasmonic materials Au, Ag, or Cu, which have high thermal conductivity and allow excellent coupling with the NFT, thus creating a confined heat source. However, Au, Ag, and Cu become significantly roughened when annealed at high temperatures. Therefore, the seed-thermal barrier layer 210 for the RL cannot be formed directly on the heat dissipation layer 206. Therefore, an intermediate layer (IL) 207 is required between the Au, Ag, or Cu heat dissipation layer 206 and the seed-thermal barrier layer 210. A seed-thermal barrier layer 210 is formed on IL 207 and serves as both a seed layer and a thermal barrier layer for RL 31. The seed-thermal barrier layer 210 is typically MgO, but other materials have been proposed, including CrRu, CrMo, TiN, and mixtures of MgO and TiO2 (MTO), such as (Mg... 0.2 Ti 0.8However, IL 207 increases the distance between RL 31 and the heat dissipation layer 206, which degrades the optical and thermal properties of the heat dissipation layer 206. US 8605555B1, assigned to the same assignee as this application, describes a HAMR medium having an amorphous IL such as CrTi, CrTa, or NiTa between the heat dissipation layer and FePt RL to reduce roughness caused by the heat dissipation layer. US 9558777B2, assigned to the same assignee as this application, describes a HAMR medium having a heat dissipation layer that can be formed from many metals and alloys including plasmon resonances Au, Ag, Cu, and Rh, but requires an IL such as amorphous NiTa between the heat dissipation layer and the MgO seed layer. Heat dissipation layers selected from non-plasmon materials Cr, W, Mo, and Ru have been proposed to replace Au, Ag, or Cu because non-plasmon materials do not become rough during annealing and therefore an intermediate layer is not required. However, the optical and thermal properties provided by these materials are not optimal.

[0031] The perpendicular medium forming RL 31 is a highly anisotropic (K) medium with perpendicular magnetic anisotropy. u Essentially chemically ordered FePt alloys (or CoPt alloys). Essentially chemically ordered means that FePt alloys possess the properties of Fe... (y) Pt (100-y) Compositions in the form of y, where y is between approximately 45 and 55 atomic percentages. Such ordered FePt (and CoPt) alloys in L10 are known for their high magnetocrystalline anisotropy and magnetization properties (desired for high-density magnetic recording materials). Bulk-form, substantially chemically ordered FePt alloys are called face-centered tetragonal (FCT) L10 ordered phase materials (also called CuAu materials). The c-axis of the L10 phase is the easy magnetization axis and is perpendicular to the disk substrate orientation. Substrate-formally chemically ordered FePt alloys can also be pseudo-binary alloys based on the FePt L10 phase, such as (Fe... (y) Pt (100-y) The RL is a pseudo-binary alloy, where y is between about 45 and 55 atomic percent, and element X can be one or more of Ni, Au, Cu, Pd, Mn, and Ag, and is present in the range of about 0% to about 20% atomic percent. Although pseudo-binary alloys generally have a similarly high anisotropy as binary alloy FePt, they allow for additional control over the magnetic and other properties of the RL. For example, Ag promotes the formation of the L10 phase, and Cu lowers the Curie temperature. Although HAMR media according to embodiments of the invention will be described using FePt RL, embodiments of the invention are also fully applicable to media having CoPt (or pseudo-binary CoPt-X alloys based on the CoPt L10 phase) RL.

[0032] Particulate films based on the FePt L10 phase exhibit strong vertical anisotropy, which potentially leads to small, thermally stable grains for ultra-high density magnetic recording. To fabricate small-grained FePt L10 media, some form of grain separator can be used as an integral part of the magnetic recording layer. Therefore, in HAMR media, RL 31 typically also includes separators formed between FePt grains and reducing grain size, such as C, SiO2, TiO2, and TaO. x One or more of ZrO2, SiC, SiN, TiC, TiN, B, BC, and BN. Although Figure 3 describes RL 31 as a single magnetic layer, the recording layer can be multiple layers, such as multiple stacked FePt sublayers, each with different separators, as described in US 9,406,329-B1, assigned to the same assignee as this application.

[0033] FePt RL is sputtered and deposited while the disk substrate 201 is maintained at an elevated temperature, for example, between about 500°C and 700°C, typically to a thickness between about 4 nm and 15 nm. FePt RL can be sputtered and deposited from a single composite target having approximately equal atomic weights of Fe and Pt, as well as desired amounts of X additives and separators, or from a single target co-sputtering.

[0034] An optional capping layer 212, such as a Co film, may be formed on RL 31. A protective outer coating (OC) 36 is deposited on RL 31 (or on the optional capping layer 212), typically to a thickness between about 1-5 nm. OC 36 is preferably an amorphous diamond-like carbon (DLC) layer. DLC may also be hydrogenated and / or nitrided, as is well known in the art. On the finished disk, a liquid lubricant 38, such as perfluoropolyether (PFPE), is coated on OC 36.

[0035] Figure 4 This is a cross-sectional view of a HAMR disk according to an embodiment of the present invention, showing the optically coupled multilayer 300 between the seed-thermal barrier layer 210 and the heat dissipation layer 206. Figure 4 The optional SUL layer is omitted. The seed-thermal barrier layer 210 is preferably MgO or MTO. The multilayer 300 includes alternating layers of non-plasmic material 302 and plasmonic material 304. Each layer 302, 304 has a thickness in the range of 0.5-2 nm, and the total thickness of the multilayer 300 is preferably in the range of 3-20 nm.

[0036] Figure 5 This is a cross-sectional view of a HAMR disk according to another embodiment of the present invention, showing an optically coupled multilayer 300 between a first seed thermal barrier film 220 and a second seed thermal barrier film 230. Each of the films 220 and 230 may be formed of MgO or MTO.

[0037] Table 1 below lists the various metals and metal alloys that can be used in layers 302 and 304, along with their corresponding n and k values ​​at 830 nm. Furthermore, various metal nitrides such as CrN, VN, WN, and MoN are suitable as non-plasmic materials because they possess lattice constants similar to Au and Ag and exhibit low overall thermal conductivity.

[0038] Table 1

[0039] Au 0.1 5.3 Ag 0.1 5.0 Cu 0.3 5.3 Rh 2.8 7.0 Non-plasmic polaritons <![CDATA[Ru 50 Al 50 ]]> 4.3 4.4 <![CDATA[Ni 50 Facing 50 ]]> 3.9 4.0 <![CDATA[Cr 50 Facing 50 ]]> 4.3 4.4

[0040] Multilayer 300 is made of alternating thin plasmonic layers separated by thin non-platinonic materials. The thickness of each individual layer is small relative to the electron mean free path of each material, which significantly reduces the thermal conductivity of each individual layer. Therefore, multilayer 300 has a low in-plane thermal conductivity (TC) preferably less than about 20 W / mK. IP Therefore, it does not function as a heat dissipation layer. For this reason, a heat dissipation layer 206 is required below the multilayer 300, and this layer can be formed from any known heat dissipation material, including Cr, W, Mo, Ru, Rh, Au, Ag, or Cu, and their alloys. However, Cr, W, and Mo, and their alloys, are preferred because they do not become rough during annealing. Figure 6 This is a list of TC measurements for RuAl / Au and RuAl / Rh multilayers with various thicknesses and alternating layer repetitions. IP The surface, multilayers are formed on a glass substrate, with a thin 2nm Au or Rh capping to prevent oxidation of the multilayers. The RuAl / Au multilayers exhibit a TC of approximately 20 W / mK. IP RuAl / Rh multilayers exhibit a TC of approximately 10 W / mK. IP Multilayer 300 also exhibits anisotropic thermal conductivity, i.e., out-of-plane thermal conductivity (TC). OP (Below TC) IP This is due to the increased scattering and decreased conductivity of heat carriers, electrons, and / or phonons encountering numerous interfaces in out-of-plane directions. Depending on the material and quality of the interfaces, interfacial thermal conductivity between metals is typically around 500 MW / m. 2 K to 4000MW / m 2 Within the range of K. This produces TC ranging from 0.5 W / mK to 10 W / mK, depending on the thermal conductivity and layer thickness at each interface. OP Multi-layered. Based on TC IP Measurement of TC in RuAl / Au multilayer OP The estimated value is approximately 10 W / mK, and the TC of RuAl / Rh multilayers is... OPThe estimated value is between 5 W / mK and 10 W / mK. In comparison, conventional heat dissipation materials such as Cr have a TC of approximately 40-45 W / mK. IP and approximately 40-45 W / mK TC OP .

[0041] The optical performance of HAMR dielectric stacks can be modeled by the ratio of the thermal gradient TG (temperature change along the track direction) to the laser power (LP) required to write 48 nm wide tracks. The higher the ratio, the better the optical efficiency of the dielectric. Figure 7 Showing data from TC IP =20W / mK and TC OP Graphical TG / LP data from computer modeling of RuAl(1nm) / Au(1nm) multilayers of various thicknesses with a density of 10 W / mK, compared to single Au plasmonic layers of various thicknesses. The baseline (TG / LP = 1) is for stacks without plasmonic layers below the seed-thermal barrier layer. The 3nm thick multilayer is RuAl(1nm) / Au(1nm) / RuAl(1nm), where RuAl is directly on the heat sink and directly below the seed-thermal barrier layer. The 9nm thick multilayer is four repetitions of the 3nm thick multilayer. Figure 8 It shows the relationship with Figure 7 The same graphical TG / LP data from computer modeling, but for two cases of RuAl(1nm) / Rh(1nm) multilayers, one of which is where TC IP =10W / mK and TC OP =5W / mK, and in one case, TC IP =10W / mK and TC OP =10W / mK.

[0042] Figure 7 and Figure 8 The modeling data for both demonstrates the optical coupling provided by the multilayer, i.e., the improvement of TG / LP relative to the baseline, where the improvement increases with the multilayer thickness (the number of repeated laminations). Similar improvements for TG / LP are also shown in the modeling data for RuAl(2nm) / Au(2nm) and RuAl(2nm) / Au(2nm) multilayers of various thicknesses. Figure 7 and Figure 8 As shown, TG / LP increases with increasing multilayer thickness, wherein the preferred thickness range is between approximately 3-20 nm.

[0043] While the invention has been specifically shown and described with reference to preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention. Therefore, the disclosed invention is considered to be exemplary only and is limited in scope to that specified in the appended claims.

Claims

1. A heat-assisted magnetic recording medium, comprising: substrate; A heat dissipation layer is located on the substrate; A magnetic recording layer comprising a chemically ordered alloy selected from FePt alloys and CoPt alloys; A seed-thermal barrier layer for the recording layer, wherein the recording layer is located on and in contact with the seed-thermal barrier layer; and The multilayer comprises alternating layers of plasmon material and layers of non-platform material, the multilayer being located between the heat dissipation layer and the seed-thermal barrier layer. The seed-thermal barrier layer includes a first film and a second film, wherein the multilayer is located between the first film and the second film, the first film is located on and in contact with the heat dissipation layer, the second film is located on and in contact with the multilayer, and the recording layer is located on and in contact with the second film.

2. The medium according to claim 1, wherein the plasmon material is selected from Au, Ag, Cu and Rh.

3. The medium according to claim 1, wherein the non-plasmic material is selected from RuAl alloy, NiTa alloy, CrTa alloy, and nitrides of Cr, V, W, or Mo.

4. The medium according to claim 1, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm.

5. The medium according to claim 1, wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.

6. The medium according to claim 1, wherein the heat dissipation layer is formed of a material selected from Cr, W, Mo and alloys thereof.

7. The medium according to claim 1, wherein the seed-thermal barrier layer is selected from MgO or MTO.

8. The medium according to claim 1, wherein the layer of non-plasmic material in the multilayer is located on and in contact with the heat dissipation layer.

9. The medium according to claim 1, wherein the magnetic recording layer further comprises a substantially chemically ordered alloy having Pt and elements selected from Fe and Co, and elements selected from C, SiO2, TiO2, and TaO. x Separators of one or more of ZrO2, SiC, SiN, TiC, TiN, B, BC and BN.

10. The medium according to claim 1, wherein the multilayer is located on and in contact with the heat dissipation layer, and the seed-thermal barrier layer is located on and in contact with the multilayer.

11. The medium according to claim 1, wherein each of the first membrane and the second membrane is selected from MgO or MTO.

12. The medium according to claim 1, wherein the plasmon material is selected from Au, Ag, Cu and Rh, and the non-platform material is selected from RuAl alloy, NiTa alloy, CrTa alloy and nitrides of Cr, V, W or Mo.

13. A heat-assisted magnetic recording (HAMR) disk drive, include: The medium according to claim 1, wherein the medium is a rotatable HAMR disk; and A carrier, which is held near the magnetic recording layer of the disk and supports the near-field transducer.

14. A heat-assisted magnetic recording (HAMR) disk, comprising: Disk substrate; A heat dissipation layer is located on the substrate; The multilayer, located on the heat dissipation layer, includes alternating layers of plasmonic material and layers of non-plasmonic material, wherein the plasmonic material is selected from Au, Ag, Cu and Rh, and the non-plasmonic material is selected from RuAl alloy, NiTa alloy, CrTa alloy and nitrides of Cr, V, W or Mo. A seed-thermal barrier layer selected from MgO or MTO, wherein the seed-thermal barrier layer is located on and in contact with the multilayer; and A magnetic recording layer selected from chemically ordered alloys of FePt and CoPt, wherein the magnetic recording layer is located on and in contact with the seed-thermal barrier layer. The seed-thermal barrier layer includes a first film and a second film, wherein the multilayer is located between the first film and the second film, the first film is located on and in contact with the heat dissipation layer, the second film is located on and in contact with the multilayer, and the recording layer is located on and in contact with the second film.

15. The disk of claim 14, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm, and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.

16. A heat-assisted magnetic recording (HAMR) disk drive, comprising: The disk according to claim 14; and A gas bearing slider is held near the magnetic recording layer of the disk and supports the near-field transducer.

17. A heat-assisted magnetic recording (HAMR) disk, comprising: Disk substrate; A heat dissipation layer is located on the substrate; A first seed-thermal barrier film selected from MgO or MTO is located on the heat dissipation layer; The multilayer comprises alternating layers of plasmonic material and layers of non-platinonic material, the multilayer being located on the first seed-thermal film, wherein the plasmonic material is selected from Au, Ag, Cu and Rh, and the non-platinonic material is selected from RuAl alloy, NiTa alloy, CrTa alloy and nitrides of Cr, V, W or Mo. A second seed-thermal barrier film selected from MgO or MTO is located on and in contact with the multilayer; and A magnetic recording layer comprising a chemically ordered alloy selected from FePt and CoPt alloys, the magnetic recording layer being located on and in contact with a second seed-thermal barrier film.

18. The disk of claim 17, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm, and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 15 nm.

19. A heat-assisted magnetic recording (HAMR) disk drive, comprising: The disk according to claim 17; and A gas bearing slider is held near the magnetic recording layer of the disk and supports the near-field transducer.

20. A heat-assisted magnetic recording medium, comprising: substrate; Heat dissipation layer; Magnetic recording layer; Seed-thermal barrier; and The multilayer comprises alternating layers of plasmon material and layers of non-platform material, the multilayer being located between the heat dissipation layer and the seed-thermal barrier layer. The seed-thermal barrier layer includes a first film and a second film, wherein the multilayer is located between the first film and the second film, the first film is located on and in contact with the heat dissipation layer, the second film is located on and in contact with the multilayer, and the recording layer is located on and in contact with the second film.

21. The medium according to claim 20, wherein the plasmon material is selected from Au, Ag, Cu and Rh.

22. The medium according to claim 20, wherein the non-plasmic material is selected from RuAl alloys, NiTa alloys, CrTa alloys, and nitrides of Cr, V, W, or Mo.

23. The medium of claim 20, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm.

24. The medium of claim 20, wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.

25. The medium of claim 20, wherein the heat dissipation layer is formed of a material selected from Cr, W, Mo and alloys thereof.

26. The medium according to claim 20, wherein the seed-thermal barrier layer is selected from MgO or MTO.

27. The medium of claim 20, wherein the layer of non-plasmic material in the multilayer is located on and in contact with the heat dissipation layer.

28. The medium of claim 20, wherein the magnetic recording layer further comprises a substantially chemically ordered alloy having Pt and elements selected from Fe and Co, and elements selected from C, SiO2, TiO2, and TaO. x Separators of one or more of ZrO2, SiC, SiN, TiC, TiN, B, BC and BN.

29. The medium of claim 20, wherein the multilayer is located on and in contact with the heat dissipation layer, and the seed-thermal barrier layer is located on and in contact with the multilayer.

30. The medium according to claim 20, wherein each of the first membrane and the second membrane is selected from MgO or MTO.

31. The medium according to claim 20, wherein the plasmon material is selected from Au, Ag, Cu and Rh, and the non-platform material is selected from RuAl alloy, NiTa alloy, CrTa alloy and nitrides of Cr, V, W or Mo.

32. A heat-assisted magnetic recording (HAMR) disk drive, comprising: The medium according to claim 20, wherein the medium is a rotatable HAMR disk; and A carrier, which is held near the magnetic recording layer of the disk and supports the near-field transducer.

33. A heat-assisted magnetic recording (HAMR) disk, comprising: Disk substrate; Heat dissipation layer; The multilayer, located on the heat dissipation layer, includes alternating layers of plasmonic material and layers of non-platinonic material; Seed-thermal barrier; and Magnetic recording layer, wherein the multilayer is disposed between the heat dissipation layer and the seed-thermal barrier layer. The seed-thermal barrier layer includes a first film and a second film, wherein the multilayer is located between the first film and the second film, the first film is located on and in contact with the heat dissipation layer, the second film is located on and in contact with the multilayer, and the recording layer is located on and in contact with the second film.

34. The disk of claim 33, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm, and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.

35. A heat-assisted magnetic recording (HAMR) disk drive, comprising: The disk according to claim 33; and A gas bearing slider is held near the magnetic recording layer of the disk and supports the near-field transducer.

36. A heat-assisted magnetic recording (HAMR) disk, comprising: Disk substrate; Heat dissipation layer; The first seed-thermal barrier film is located on the heat dissipation layer; The multilayer, located on the first seed-thermal film, comprises alternating layers of plasmon material and layers of non-platinum material; The second seed-thermal barrier membrane is located on and in contact with the multilayer; and A magnetic recording layer, which is located on and in contact with the second seed-thermal barrier film.

37. The disk of claim 36, wherein each of the plasmonic material layer and the non-platinonic material layer has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm, and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 15 nm.

38. A heat-assisted magnetic recording (HAMR) disk drive, comprising: The disk according to claim 36; and A gas bearing slider is held near the magnetic recording layer of the disk and supports the near-field transducer.

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