CN117912504A

CN117912504A - Magnetic recording medium with multiple soft underlayers and magnetic recording device used therewith

Info

Publication number: CN117912504A
Application number: CN202311312276.9A
Authority: CN
Inventors: A·巴希尔; P-O·朱伯特; A·阿健; P·C·多尔西
Original assignee: Western Digital Technologies Inc
Current assignee: Western Digital Technologies Inc
Priority date: 2022-10-19
Filing date: 2023-10-11
Publication date: 2024-04-19

Abstract

Various devices, systems, methods, and media for thermally assisted magnetic recording (HAMR) are disclosed, which in some examples provide a HAMR medium with two Soft Underlayer (SUL) on opposite sides of a single heat sink layer. For example, a magnetic recording medium including a lower SUL on a substrate is provided. The lower SUL is configured and positioned within the medium to provide a first return path for magnetic flux from the magnetic recording head during a write operation. The medium also includes a heat sink layer on the lower SUL and an upper SUL on the heat sink layer. The upper SUL is configured and positioned within the medium to provide a second return path for magnetic flux from the magnetic recording head. A magnetic recording layer is disposed on the upper SUL to store information during the write operation. Additional layers or films may also be provided.

Description

Magnetic recording medium with multiple soft underlayers and magnetic recording device used therewith

Cross Reference to Related Applications

The present application claims the priority and benefit of U.S. provisional patent application No. 63/417,622, entitled "magnetic recording media with multiple soft underlayer and magnetic recording apparatus (MAGNETIC RECORDING MEDIUM WITH MULTIPLE SOFT UNDERLAYERS AND MAGNETIC RECORDING APPARATUS FOR USE THEREWITH)" for use therewith," filed on day 10 and 19 of 2022, the entire contents of which are incorporated herein by reference as if fully set forth below and for all applicable purposes.

Technical Field

In some aspects, the present disclosure relates to magnetic recording media and magnetic recording devices for use with magnetic recording media. More particularly, but not exclusively, the present disclosure relates to magnetic recording media with a Soft Underlayer (SUL) configured for use with Heat Assisted Magnetic Recording (HAMR).

Background

Magnetic storage systems, such as Hard Disk Drives (HDDs), are used in a variety of devices in stationary and mobile computing environments. Examples of devices that incorporate magnetic storage systems include desktop computers, portable notebook computers, portable hard drives, high Definition Television (HDTV) receivers, television set-top boxes, video game controllers, and portable media players.

A typical disk drive includes a magnetic storage medium in the form of one or more flat disks. Magnetic disks are typically formed from a few major materials, namely a substrate material that imparts structure and rigidity thereto, a magnetic recording layer that retains magnetic pulses or moments that store digital data, and a dielectric overcoat and lubricant layer to protect the magnetic recording layer. Typical disk drives also include read and write heads, typically in the form of magnetic transducers that can sense and/or alter the magnetic moment stored on the recording layer of the disk.

Thermally assisted magnetic recording (HAMR) systems can increase the areal density of magnetically recorded information on various magnetic media. To achieve higher areal densities for magnetic storage, smaller magnetic grain sizes (e.g., less than 6 nanometers (nm)) may be required. In HAMR, a high temperature is applied to the medium during writing to facilitate recording of small grains that have high magnetic anisotropy by design. The high temperature may be achieved using a near field transducer of a laser diode coupled to the slider of the HAMR disk drive.

At least some magnetic recording media used with HAMR employ a Soft Underlayer (SUL) below the magnetic recording layer that provides a return path for magnetic flux from the magnetic recording head of the slider during a write operation. Aspects of the present disclosure relate to configuring and locating such SUL layers.

Disclosure of Invention

The following presents a simplified summary of some aspects of the disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended to neither identify key or critical elements of all aspects of the disclosure nor delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present various concepts of some aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

In one embodiment, there is provided a magnetic recording medium including: a substrate; a first Soft Underlayer (SUL) located on the substrate, wherein the first SUL is configured and positioned within the magnetic recording medium to provide a first return path for magnetic flux; a heat sink layer located on the first SUL; a second SUL located on the heat sink layer, wherein the second SUL is configured and positioned within the magnetic recording medium to provide a second return path for magnetic flux that is different from the first return path; and a magnetic recording layer located on the second SUL. The magnetic recording medium may be a Heat Assisted Magnetic Recording (HAMR) medium.

In another embodiment, there is provided a magnetic recording medium including: a substrate; an adhesion layer directly on the substrate; a first SUL located directly on the adhesion layer; a heat sink layer directly on the first SUL; a second SUL located on the heat sink layer; and a magnetic recording layer located on the second SUL. The magnetic recording medium may be a HAMR medium.

In another embodiment, a magnetic recording apparatus is provided that includes a magnetic recording head; and a magnetic recording medium including: a substrate; a first SUL located on the substrate, wherein the first SUL has a top surface no more than 125nm from the magnetic recording head while the magnetic recording head is positioned to write data to the magnetic recording medium; a heat sink layer located on the first SUL; a second SUL located on the heat sink layer, wherein the second SUL has a top surface no more than 40nm from the magnetic recording head while the magnetic recording head is positioned to write data to the magnetic recording medium; and a magnetic recording layer located on the second SUL. The magnetic recording device may be a HAMR device.

In another embodiment, a method for manufacturing a magnetic recording medium is provided. The method comprises the following steps: providing a substrate; providing an adhesion layer directly on the substrate; providing a first soft cushioning layer (SUL) directly on the adhesive layer; providing a heat sink layer directly on the first SUL; providing a second SUL located on the heat sink layer; and providing a magnetic recording layer on the second SUL. The magnetic recording medium manufactured may be a HAMR medium.

These and other aspects of the disclosure will be more fully understood upon reading the detailed description that follows. Other aspects, features and implementations of the disclosure will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the disclosure in conjunction with the accompanying drawings. While features of the present disclosure may be discussed with respect to certain implementations and figures below, all implementations of the disclosure may include one or more of the advantageous features discussed herein. In other words, while one or more implementations may be discussed as having certain advantageous features, one or more of these features may also be used in accordance with the various implementations of the disclosure discussed herein. Similarly, while certain implementations may be discussed below as device implementations, system implementations, or method implementations, it should be understood that such implementations may be implemented in a variety of devices, systems, and methods.

Drawings

The following more particular description is included with reference to specific aspects shown in the accompanying drawings. Understanding that these drawings depict only certain aspects of the disclosure and are not therefore to be considered limiting of its scope, the disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a top view schematic illustration of an exemplary disk drive configured for thermally assisted magnetic recording (HAMR) including a slider and a HAMR medium including at least two Soft Underlayer (SUL) on opposite sides of a single heatsink layer in accordance with aspects of the present disclosure.

FIG. 2 is a side view schematic illustration of the example slider and HAMR medium of FIG. 1 in accordance with aspects of the present disclosure.

FIG. 3 is a side view schematic illustration of an exemplary HAMR medium comprising, among other layers, two SULs on opposite sides of a single heatsink layer, in accordance with aspects of the present disclosure.

FIG. 4 is a flowchart of an exemplary process for manufacturing a HAMR medium comprising, among other layers, two SULs on opposite sides of a single heatsink layer, according to aspects of the present disclosure.

FIG. 5 is a side view schematic illustration of an exemplary HAMR medium and HAMR write head, wherein the HAMR medium comprises two SULs in some examples, in accordance with aspects of the present disclosure.

FIG. 6 is a side view schematic illustration of an exemplary HAMR medium and HAMR write head, wherein the HAMR medium comprises two or more SULs in some examples, in accordance with aspects of the present disclosure.

FIG. 7 includes graphs illustrating exemplary experimental results for various HAMR media designs, including dual SUL designs, in accordance with aspects of the present disclosure.

FIG. 8 includes graphs illustrating exemplary experimental results for various HAMR media designs including dual SUL designs, wherein the results for dual SUL designs appear as a percentage increase relative to a single SUL design, in accordance with aspects of the disclosure.

FIG. 9 is a side view schematic illustration of an exemplary magnetic recording medium including at least two SULs located on opposite sides of a heat sink layer, according to aspects of the present disclosure.

FIG. 10 is a side schematic view of another exemplary magnetic recording medium including at least two SULs on opposite sides of a heat sink layer, wherein at least some of the layers are formed directly on other layers, according to aspects of the present disclosure.

FIG. 11 is a side schematic view of an exemplary magnetic recording apparatus including a magnetic recording head and a magnetic recording medium having at least two SULs located on opposite sides of a heat sink layer in accordance with aspects of the present disclosure.

FIG. 12 is a flowchart of an exemplary process for manufacturing a magnetic recording medium including at least two SULs on opposite sides of a heat sink layer, according to aspects of the present disclosure.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In addition to the exemplary aspects, aspects and features described above, further aspects, aspects and features will become apparent by reference to the drawings and the following detailed description. The description of elements in each figure may refer to elements of previous figures. Like numbers may refer to like elements throughout, including alternative aspects of like elements.

In some aspects, the present disclosure relates to various apparatuses, systems, methods, and media for providing a magnetic recording medium, such as a Heat Assisted Magnetic Recording (HAMR) medium, wherein the magnetic recording medium may increase the magnetic field strength achieved within its magnetic recording layer during write operations, among other features, while also providing good thermal properties, layer deposition properties, and other features. In some aspects, these features are achieved by employing at least two cushion layers (SULs), such as dual SUL HAMR media, on opposite sides of the heat sink layer.

Prior to discussing dual SUL HAMR media, HAMR media having a single SUL will be described. An exemplary single SUL HAMR medium may include the following layers (in bottom-to-top order): a substrate; an adhesive layer for reducing delamination of subsequently deposited layers; a single SUL for providing a return path for magnetic flux from the magnetic recording head during a write operation; a heat sink layer for controlling heat flow (particularly lateral heat flow) within the HAMR medium; a seed layer for promoting growth of the granular magnetic recording layer and further providing a thermal barrier between the recording layer and the heat sink layer; a granular magnetic recording layer; a magnetic capping layer that facilitates magnetization reversal of magnetic grains in the granular magnetic recording layer; and an overcoat layer, such as a carbon overcoat layer (COC). In some examples, the seed layer is made of a MgO layer, a MgO-TiO (MTO) layer, or a suitable oxide layer, or multiple layers of the same material. In an exemplary HAMR medium, the SUL provides the closest flux closed loop for the magnetic write head.

In an exemplary HAMR system, the write head includes a main pole and one or more return poles. For HAMR systems, the return pole is typically about 500nm from the main pole tip, as opposed to Perpendicular Magnetic Recording (PMR) systems, where the distance between the poles is typically less than 20 nm. Given the relatively large distance of 500nm of HAMR systems, it is important to design and configure HAMR media to enhance their writability. Within such media, the head-to-SUL distance (HUS) is typically large, e.g., 120nm or more, due to the thickness of many layers (e.g., heat sink layer, seed layer, MTO layer, mgO layer, etc.) interposed between the top of the SUL and the top of the HAMR medium. Since HUS is large, the SUL is typically made quite thick to compensate for its distance from the write head pole in order to maximize the magnetic write field in the magnetic recording layers, thereby achieving write saturation in those layers. For example, the SUL may be 80nm thick. However, thick SULs may be difficult to deposit. Thus, the magnetic flux strength within the magnetic recording layer during write operations cannot generally be increased by providing a SUL thicker than 80nm without encountering SUL deposition problems.

It is therefore desirable to provide a HAMR medium configured to increase the magnetic field strength within its magnetic recording layer during write operations without the need to deposit a thicker SUL (and while also achieving good thermal characteristics, etc. within the HAMR medium).

There is provided a magnetic recording medium, in one aspect, comprising: a substrate; a first SUL located on the substrate, wherein the first SUL is configured and positioned within the magnetic recording medium to provide a first return path for magnetic flux (e.g., from a magnetic recording head during a write operation); a heat sink layer located on the first SUL; a second SUL located on the heat sink layer, wherein the second SUL is configured and positioned within the magnetic recording medium to provide a second return path for magnetic flux (e.g., from a magnetic recording head during a write operation) that is different from the first return path; and a magnetic recording layer (e.g., configured to store information during a write operation) located on the second SUL.

Thus, in some aspects, two SUL layers are provided, one below the heat sink and the other above the heat sink. The higher (second) SUL may be much thinner than the lower (first) SUL and may be deposited, for example, above the heat sink but below the seed layer and thus also below the magnetic recording layer. The addition of a higher (second) SUL serves to increase the magnetic field strength within the magnetic recording layer during write operations, as compared to a corresponding medium having only a lower SUL located below the heat sink. In an exemplary embodiment, the higher (second) SUL is 25nm thick. In one example, the lower (first) SUL may be 55nm thick, and in another example, 80nm thick.

In this way, the magnetic field strength within the magnetic recording layer during a write operation may be increased without a corresponding increase in the thickness of the lower SUL, and in some examples, while allowing for a significant reduction in its thickness (e.g., from 80nm to 55 nm). In some examples, a 10% to 15% increase in magnetic field strength within the magnetic recording layer is achieved compared to HAMR media having only a lower SUL located below the heat sink. Notably, in these examples, there is only a single heatsink layer between the lower (first) SUL and the upper (second) SUL. No separate heat sink layer is needed under the lower (first) SUL.

Illustrative examples and embodiments

FIG. 1 is a schematic top view of a data storage device 100 (e.g., a magnetic disk drive or magnetic recording device) configured for magnetic recording and including a slider 108 and a magnetic recording medium 102. In the exemplary embodiment, magnetic recording medium 102 includes a HAMR medium that includes at least two SULs (not shown in fig. 1, but see fig. 3). A laser (not visible in fig. 1, but see 114 in fig. 2) is positioned with the head/slider 108. The disk drive 100 may include one or more disks/media 102 to store data. The disk/media 102 resides on a spindle assembly 104 that is mounted to a drive housing 106. Data may be stored along tracks in the magnetic recording layer of the disk 102. Reading and writing of data is accomplished with a head 108 (slider) that may have both read and write elements (108 a and 108 b). The write element 108a is used to change the properties of the magnetic recording layer of the magnetic disk 102 and thus write information to the magnetic disk. In one aspect, the head 108 may have a magneto-resistive (MR) based element, such as a tunneling magneto-resistive (TMR) element for reading, and a write pole with a coil that can be energized for writing. In operation, a spindle motor (not shown) rotates the spindle assembly 104, and thus the disk 102, to position the head 108 at a particular location along the desired disk track 107. The position of the head 108 relative to the disk 102 may be controlled by control circuitry 110 (e.g., a microcontroller). It is noted that while an exemplary HAMR system is shown, at least some aspects of the present disclosure may be used in other HAMR or EAMR magnetic data recording systems or in non-HAMR or non-EAMR magnetic data recording systems, including shingled write magnetic recording (SMR) media, perpendicular Magnetic Recording (PMR) media, or microwave-assisted magnetic recording (MAMR) media.

FIG. 2 is a schematic side view of the slider 108 and magnetic recording medium 102 of FIG. 1. The magnetic recording medium 102 includes at least two SULs (not shown in FIG. 1, but see FIG. 3). The slider 108 (which may also be referred to as a head) may include a sub-mount 112 attached to a top surface of the slider 108. The laser 114 may be attached to the submount 112 and possibly to the slider 108. The slider 108 includes a write element (e.g., writer) 108a and a read element (e.g., reader) 108b positioned along an Air Bearing Surface (ABS) 108c of the slider to write information to and read information from the medium 102, respectively. In other aspects, the slider may also include a layer of Si or Si cladding 120. This layer is optional.

In operation, the laser 114 is configured to generate and direct light energy to a waveguide (e.g., along a dashed line) in the slider that directs the light to a Near Field Transducer (NFT) 122 proximate an air bearing surface (e.g., bottom surface) 108c of the slider 108. Upon receiving light from laser 114 via the waveguide, NFT 122 generates localized thermal energy that heats a portion of medium 102 within and near writing element 108 a. Recording temperatures in the range of about 350 ℃ to 400 ℃ are contemplated. In the aspect shown in FIG. 2, laser directed light is disposed within writer 108a and near the trailing edge of the slider. In other aspects, the laser directed light may instead be positioned between writer 108a and reader 108 b. Fig. 1 and 2 illustrate a specific example of a HAMR system. In other aspects, magnetic recording medium 102 may be used in other suitable HAMR systems (e.g., with other sliders configured for HAMR).

FIG. 3 is a side view schematic illustration of an exemplary HAMR medium 300 comprising two SULs on opposite sides of a heat sink layer in accordance with aspects of the present disclosure. HAMR medium 300 of fig. 3 has a stacked structure with a substrate (which may be formed, for example, of glass or glass-ceramic) 302 at an underlayer/base layer, an adhesion layer 304 (which may be formed, for example, of NiTa) on substrate 302, a first (lower) SUL 308 (which may be formed, for example, of CoZrWMo) on adhesion layer 304, a heat sink layer 310 (which may be formed, for example, of Cr) on lower SUL 308, a second (higher) SUL 312 (which may be formed, for example, of CoZrWMo) on heat sink layer 310, a seed layer 314 (which may include an MgO layer and an MTO layer as described above) on upper SUL 312, wherein the MgO layer is on top of the MTO layer, a Magnetic Recording Layer (MRL) 316 (which may be formed, for example, of FePt) on seed layer 314, a capping layer 318 (which may be formed, for example, of CoFe), and COC 320 on capping layer 318. Although not shown, an additional lubricant layer may be located on COC layer 320. It is noted that the layers in fig. 3 (and in other figures herein) are not shown to scale.

As used herein, the terms "above … …," "below … …," "over … …," and "between … …" refer to the relative position of one layer with respect to the other. Thus, one layer deposited or disposed on, over, or under another layer may be in direct contact with the other layer, or may have one or more intervening layers. Furthermore, a layer deposited or disposed between layers may be in direct contact with the layers or may have one or more intervening layers.

In some aspects, the layer has the following thickness: the thickness of the substrate 302 is in the range of 0.5mm to 0.635 mm; the adhesion layer 304 has a thickness in the range of 45nm to 180 nm; the lower SUL 306 thickness is in the range of 55nm to 80 nm; the heat sink layer 310 has a thickness in the range of 55nm to 100 nm; the higher SUL 312 thickness is about 25 (and in the range of 10nm to 30 nm); the seed layer 314 thickness is in the range of 2nm to 5nm (and is made of MgO, or alternatively MgO-TiO, or other suitable oxide layer that promotes FePt ordering and provides a good thermal barrier between the recording layer and the heat sink layer); the MRL structure may be, for exampleTo/>Thickness; the capping layer 318 has a thickness in the range of 1nm to 3 nm; COC 320 thickness at 30 angstroms/>To/>Is within the range of (2); lubricant layer thickness (if provided) at/>To/>Within a range of (2).

In some embodiments, the substrate 302 has an outer diameter (i.e., OD) of about 97mm and a thickness of about 0.5 mm. In other embodiments, the OD may be 95mm or 95.1mm. (generally, such disks are referred to as "3.5 inch" disks). In some aspects, the substrate 302 may be made of one or more materials (such as Al alloys, niP plated Al, glass-ceramic, and/or combinations thereof).

In some aspects, the adhesion layer 304 (which may alternatively be referred to as a pre-seed layer) is used to reduce delamination of layers or films deposited over the adhesion layer. Adhesion layer 304 may be a metal alloy, such as NiTa (as shown), or the like.

In some aspects, the lower SUL 308 may be configured by CoZrWMo. In other examples, the lower SUL 308 may be made of one or more other soft magnetic materials, such as one or more of Co, fe, or Ni and W, mo, ta, nb, cr, B, si or C, or a combination thereof. Thus, in some aspects, the lower SUL 308 may be made of a metallic material, such as CoZrWMo, coW, niFe or CoNiFe, or a combination thereof. In some examples, additional nonmetallic materials may be added to the metallic material, such as CrTa or ZrO ₂. In some examples, the SUL is formed of Co or CoFe alloys with Zr, B, ta, W, mo additives (to make the layer soft magnetic and amorphous). The lower SUL 308 may be an amorphous compound without anisotropy. The lower SUL 308 may be configured and positioned to support the magnetization of the magnetic recording layer structure 316 during data storage operations. More specifically, the lower SUL 308 may be configured and positioned to provide a first return path for magnetic fields applied during a write operation. Although various materials may be used to form the lower SUL 308, the lower SUL 308 is preferably configured from a material having a saturation magnetic flux density (B _S) greater than 1.2 Tesla (T) and having, for example, B _S in the range of 1.4T to 1.6T. CoZrWMo is one example of a material having such a high B _S value.

In some aspects, the heat sink layer 310 may be made of one or more materials, such as Cr (as shown) or Ag, al, au, cu, mo, ru, W, cuZr, moCu, agPd, crRu, crV, crW, crMo, crNd, niAl, niTa, combinations thereof, and/or other suitable materials known in the art.

In some aspects, the upper SUL 312 may be configured to be the same as the lower SUL 308, at least with respect to material composition. That is, the upper SUL 312 may be formed of CoZrWMo. In other examples, the higher SUL 312 may be made of one or more other soft magnetic materials, such as one or more of Co, fe, ni, and W, mo, ta, nb, cr, B, si, zr or C, or a combination thereof. The upper SUL 312 may be an amorphous compound without anisotropy. The upper SUL 312 may be configured and positioned to further support the magnetization of the magnetic recording layer structure 316 during data storage operations. More specifically, the upper SUL 312 may be configured and positioned to provide a second return path for the magnetic field applied during the write operation. As with the lower SUL 308, the upper SUL 312 is preferably configured from a material having a B _S value greater than 1.2T and, for example, having a B _S in the range of 1.4T to 1.6T. CoZrWMo are likewise examples of materials having such high B _S values.

While lower SUL 308 and upper SUL 312 may be formed of the same material, they need not be the same, and in some examples, the two SUL layers may be formed of different materials. The lower SUL 312 should be configured to have a low thermal conductivity to act as a thermal barrier rather than a heat sink. Still further, the upper SUL 312 should be placed as close to the top of the media as possible (and thus as close to the write head as possible). The higher SUL 312 should also remain fairly thin (e.g., less than 30 nm) because a thicker higher SUL may block heat from reaching the heat sink and reduce thermal gradients. The thermal gradient is a measure of the thermal distribution into the medium that results from the NFT. Generally, higher gradients are preferred. The higher SUL 312 and various other layers, such as MgO and MTO, may be configured and positioned to achieve a desired thermal gradient, among other thermal performance parameters.

In some aspects, seed layer 314 is used to form a growth template for subsequently deposited films (including heat sink layer 310 and MRL 316), and to provide the correct crystallographic orientation, e.g., L1 ₀. Functional goals of the seed layer 314 include small grain size and good crystallographic texture, both of which may be desirable for good media recording performance. In some aspects, seed layer 314 may include an MTO layer to facilitate nucleation in order to allow for proper crystal growth within MRL 316 such that MRL 316 will have a good crystallographic texture with small grains. In some aspects, the seed layer may include a MgO layer to facilitate nucleation in order to allow proper crystal growth within MRL 316 and in combination with the MTO layer provide a thermal barrier.

In some aspects, MRL 316 includes one or more magnetic recording layers for magnetically storing data, not explicitly shown in FIG. 3. For example, MRL 316 may include a magnetic recording sublayer and an exchange control sublayer (ECL). These sublayers together form an MRL structure 316, which may be, for exampleTo/>Thick. In some aspects, MRL 316 may be made of FePt. In some aspects, MRL 316 may instead be made from an alloy selected from FePtY, where Y is a material selected from Cu, ni, and combinations thereof. In other aspects, MRL 316 may instead be made of a CoPt alloy. In some aspects, MRL 316 may be formed from highly anisotropic L1 ₀ FePt with a partitioning ion (such as C, BN, siO ₂, ag, and combinations thereof). In some aspects, the MRL is a four layer MRL. Each layer of the MRL may have an ion, where the amount of ion that is separated varies from layer to layer within the MRL.

In some aspects, capping layer 318 is magnetic and may be made of CoFe, coPt, coPd, co only, or other suitable materials known in the art.

In some aspects, if a lubricant layer is also provided on COC 320, the lubricant layer (not shown) may be made of a polymer-based lubricant material.

Notably, FIG. 3 shows an exemplary embodiment of a HAMR stack with a specific combination and arrangement of layers. In other examples, more or fewer layers may be formed. For example, in some examples, the MTO may be omitted or the adhesion layer may be omitted. In other examples, additional layers or films, such as a thermal resistance layer (which may be formed of RuAlTiO ₂, for example), may be provided above the heat sink and below the upper SUL. In some cases, the sequential positioning of the SULs within a layer may vary. For example, the higher SUL may be positioned above the MTO/MgO, or the seed layer may be located below the heat sink but above the lower SUL. Generally, various arrangements may present various tradeoffs in terms of different properties (e.g., thermal versus magnetic properties).

FIG. 4 is a flow chart of a process 400 for manufacturing a HAMR medium comprising at least two SULs on opposite sides of a heatsink layer, in accordance with aspects of the present disclosure. In one aspect, process 400 may be used to fabricate the HAMR medium described above with respect to fig. 3. In block 402, the process provides a substrate. In block 404, the process provides an adhesion layer (which may be formed of NiTa, for example) on the substrate. In block 406, the process provides a first (lower) SUL (which may be formed, for example, of CoZrWMo) located on the adhesion layer. In block 408, the process provides a heat sink layer (which may be formed of Cr, for example) located on the lower SUL. In block 410, the process provides a second (higher) SUL (which may be formed, for example, of CoZrWMo) located on the heat sink layer. In block 412, the process provides a seed layer (which may include a MgO layer and an MTO layer as described above) on the upper SUL. In block 416, the process provides an MRL on the seed layer. In block 418, the process provides a capping layer (which may be formed of CoFe, for example) on the MRL. In block 420, the process provides the COC on the capping layer and then preferentially etches the COC. Although not shown, the process may also provide a lubricant layer on the COC. Additional or alternative exemplary materials are listed above.

As with the processes described herein, these processes may, in some cases, perform a sequence of actions in a different order. In another aspect, the process may skip one or more of the actions. In other aspects, one or more of the acts are performed concurrently. In some aspects, additional actions may be performed. Deposition of at least some of these layers may be performed using various deposition processes or sub-processes, including, but not limited to, physical Vapor Deposition (PVD), sputter deposition and ion beam deposition, plasma Enhanced Chemical Vapor Deposition (PECVD) and other forms of Chemical Vapor Deposition (CVD) other than PECVD, low Pressure Chemical Vapor Deposition (LPCVD), and Atomic Layer Chemical Vapor Deposition (ALCVD). In other aspects, other suitable deposition techniques known in the art may also be used.

FIG. 5 is a side view schematic of four exemplary HAMR media highlighting the upper SUL and lower SUL and showing exemplary HUS values and other distance or thickness parameters. An important parameter in terms of magnetic write performance is the distance from the top surface of the SUL to the main pole of the write head of the HAMR drive, i.e., HUS value. From a media manufacturing perspective, a key parameter is the distance from the top surface of the SUL to the top of the HAMR media stack, as the distance is properly selected in conjunction with the head-to-media spacing (HMS) during writing, the top surface of the SUL can be set to an appropriate HUS value to maximize magnetic write performance. In each of the examples of fig. 5, the HMS is 10nm. In other HAMR drivers, the HMS may be different. Note that in fig. 5, each HAMR media stack is shown in dashed lines, with only the SUL shown in solid lines. That is, FIG. 5 does not show various other layers and films within the HAMR medium. See also fig. 3 for an exemplary embodiment including various other layers and films.

Design 500 is a HAMR medium with a single SUL. In this example, the SUL has a thickness of 80nm, its top surface is positioned 120nm from the main pole of the write head (i.e., HUS is 120 nm), and its top surface is positioned 110nm from the top of the HAMR medium stack. Although not shown in fig. 5, the fin layer is located above a single SUL. See also fig. 3.

Design 502 is a first exemplary dual SUL HAMR medium. In this example, the lower SUL is configured and positioned the same as a single SUL of design 500; that is, the lower SUL has a thickness of 80nm with its top surface positioned 120nm from the main pole of the write head and 110nm from the top of the HAMR medium stack. The higher SUL of design 502 has a thickness of 25nm with its top surface positioned 35nm from the main pole of the write head (i.e., HUS is 35 nm) and 25nm from the top of the HAMR media stack. Although not shown in fig. 5, the fin layer is located below the upper SUL and above the lower SUL, and the MRL is located above the upper SUL. See also fig. 3. By providing a dual SUL configuration of design 502, improved magnetic performance may be achieved compared to a single SUL of design 500. In some examples, the magnetic field strength within the MRL in design 502 is 10% to 15% greater than single SUL design 500.

Design 504 is a second exemplary dual SUL HAMR medium. In this example, the lower SUL has a thickness of 55nm with its top surface positioned 120nm from the main pole of the write head and 110nm from the top of the HAMR medium stack. The higher SUL of design 503 also has a thickness of 25nm with its top surface positioned 35nm from the main pole of the write head (i.e., 35nm for HUS) and 25nm from the top of the HAMR media stack. Although not shown in fig. 5, a heat sink layer is also provided below the upper SUL and above the lower SUL, and an MRL is provided above the upper SUL. See also fig. 3. Although a thinner SUL is used as the lower SUL (e.g., 55nm and 80 nm), good magnetic performance may be achieved compared to a single SUL with its design 500 of an 80nm SUL.

Design 506 is a third exemplary dual SUL HAMR medium. In this example, the lower SUL also has a thickness of 55nm, but its top surface is positioned 145nm from the main pole of the write head and 135nm from the top of the HAMR medium stack. The higher SUL of design 504 also has a thickness of 25nm with its top surface positioned 35nm from the main pole of the write head (i.e., 35nm for HUS) and 25nm from the top of the HAMR media stack. Although not shown in fig. 5, a heat sink layer is also provided below the upper SUL and above the lower SUL, and an MRL is provided above the upper SUL. See also fig. 3. By locating the lower SUL away from the higher SUL, a thicker layer of fins is accommodated by this particular design.

Thus, fig. 5 shows various examples of a dual SUL design. Other layers of the HAMR stack are not explicitly shown in the figures to emphasize that various different combinations or arrangements of other HAMR layers may be provided within the available space between the SULs of fig. 5. An example of such other layers is shown in fig. 3. From a magnetic write performance standpoint, the upper SUL and lower SUL may be configured and positioned as shown in FIG. 5 with HUS values that optimize (or at least improve) magnetic write performance. Other layers may be configured and positioned above, below, or between the SUL layers to achieve other objectives. For example, design 506 accommodates thicker heat sink layers, which may be advantageous in some HAMR drives. Design 504 may allow the entire HAMR stack to be thinner than the HAMR stack of design 502 while using the same thickness of heat sink. Thus, there is considerable flexibility in the design of HAMR stacks. Furthermore, at least some dual SUL designs benefit from being relatively thin (e.g., 55nm instead of 80 nm). As described above, there is the advantage of a thinner SUL during deposition.

In some aspects, once the intended HMS is known, the HAMR stack may be designed to achieve the desired HUS value by selecting the thickness of the layers of the HAMR stack to place the top surfaces of the upper and lower SULs at the desired HUS location. Depending on the particular embodiment, this may involve setting or adjusting the thickness of other layers (such as a heatsink layer) to position the SUL at a particular depth within the HAMR stack to provide a desired HUS value during a write operation. In other examples, this may involve rearranging the order of layers (such as by repositioning any required seed layers) to locate the SUL to provide a desired HUS value during a write operation. It should also be noted that if the HMS is less than the exemplary 10nm, the SUL may be positioned lower within the HAMR stack to achieve the desired HUS value. On the other hand, if the HMS is greater than the exemplary 10nm, then both SULs may be positioned higher within the HAMR stack to also achieve the desired HUS value. In other examples, the driver's HMS may be adjusted to set the HUS to a preferred or optimal value.

Fig. 6 highlights the flexibility of SUL layer positioning. As shown in fig. 5, a first design 600 shows a single SUL with a specific thickness and HUS value. Second design 602 is a dual SUL design with a higher SUL and a lower SUL, which shows that each of the thickness value and the distance value (e.g., the HUS value) are variable (var.) because they can be adjusted during the design phase of the HAMR medium to achieve a preferred or optimal HUS value or other parameter. Third design 606 is a three SUL design with a higher SUL, a middle SUL, and a lower SUL, again showing that each of the thickness value and the distance value are variable. Generally, there may be N SUL layers, where N may be 2, 3,4, or any practical number.

It should be appreciated that once the HAMR stack is fabricated, the thickness of the layers and their relative distances from the top and bottom of the stack are no longer variable, but rather are fixed within the final structure. Variability occurs during the design phase.

In some examples, the relative thicknesses of the various SULs may be specified in terms of thickness ratios during the design phase. For example, the thickness ratio of the higher SUL to the lower SUL may be in the range of 1:2 to 1:5, depending on the particular embodiment. In design 502 of FIG. 5, where the upper SUL is 25nm and the lower SUL is 80nm, the ratio is 1:3.2. In design 504 of FIG. 5, where the upper SUL is 25nm and the lower SUL is 55nm, the ratio is 1:2.2. In some aspects, the thickness of the SUL may be set to achieve certain advantageous ratios, such as ratios in the range of 1:2 to 1:4 or in the narrower range of 1:2.2 to 1:3.2. In some aspects, the thicknesses are set to achieve a combined target thickness. For example, the combined target thickness for both the higher and lower SULs may be 80nm (as in design 504 of fig. 5), with the lower SUL being made thinner (e.g., 55 nm) to accommodate the higher SUL (e.g., 25 nm).

FIG. 7 provides a graph 700 of exemplary finite element modeling results for the four designs shown in FIG. 5. The Y-axis of plot 700 represents the strength of the perpendicular magnetic field (Hperp) within the MRL of the HAMR medium in oersted (Oe). The X-axis shows the coil current Iw in mA for (providing for) exciting the write head. The write current Iw may be applied in the range of 30mA to 130mA depending on the number of coil turns. In the modeling results presented here, the write head has three turns of excitation coil.

The first curve 702 of fig. 7 represents the first dual SUL design of fig. 5: design 502. A second curve 704 represents the second dual SUL design of fig. 5: design 504. Third curve 706 represents the third dual SUL design of fig. 5: design 506. Fourth curve 708 represents the single SUL design of fig. 5: design 500. As shown in fig. 7, each of the curves shows Hperp that increases in intensity with increasing Iw. Further, at each Iw value, each of the dual SUL designs exhibits improvements over the single SUL design, with design 502 providing the best Hperp (as shown by curve 702). As shown in fig. 7, the greatest relative improvement in field strength for the dual SUL design is achieved at smaller Iw values, and therefore at the highest write density, compared to the single SUL design. This will be further illustrated in the following figures.

Fig. 8 provides a graph 800 showing the same results as fig. 7, but the increase of Hperp is expressed as a percentage increase relative to a single SUL design. That is, the Y-axis of graph 800 represents the percentage increase in the Hperp magnetic field strength within the MRL of the HAMR medium implemented using the dual SUL design of FIG. 5 as compared to the baseline magnetic field strength implemented by the single SUL design of FIG. 5. The X-axis also shows Iw. Thus, FIG. 8 conveniently shows that the highest increase Hperp occurs at the highest write density when a dual SUL design is used.

Additional examples and embodiments

FIG. 9 is a side schematic view of an exemplary magnetic recording medium 900 according to another aspect of the present disclosure. The medium 900 has a stacked structure with a substrate 902 and a first (lower) SUL 904 located on the substrate 902, wherein the first SUL 904 is configured and positioned within the magnetic recording medium 900 to provide a first return path (e.g., for magnetic flux from a magnetic recording head (not shown in FIG. 9) during a write operation). The media 900 also has a heat sink layer 906 located over the first SUL 904 and a second (higher) SUL 908 located over the heat sink layer 906, wherein the second SUL 908 is configured and positioned within the magnetic recording media 900 to provide a second return path for magnetic flux (e.g., from the magnetic recording head during a write operation) that is different than the first return path. MRL 910 is located on second SUL 908. Medium 900 may be a HAMR medium.

In some aspects, the substrate 902 may be made of one or more materials (such as Al alloys, niP plated Al, glass-ceramic, and/or combinations thereof). In some aspects, the fin layer 906 may be made of Cr. In some aspects, MRL 910 may be made of FePt. In some aspects, MRL 910 may instead be made from an alloy selected from FePtY, where Y is a material selected from Cu, ni, and combinations thereof. In other aspects, MRL 910 may instead be made of a CoPt alloy. In some aspects, the MRL 910 may be formed from highly anisotropic L1 ₀ FePt with separation. In some examples, MRL 910 may include one or more magnetic recording layers, which are not explicitly shown in FIG. 9. As described above, additional layers of HAMR media may be provided, such as an MTO layer, an MgO layer, and a seed layer.

In some aspects, the first SUL 904 is configured and positioned by: (a) Configuring SUL 904 with a specific material having a high B _S, such as CoZrWMo, and having a specific SUL thickness, such as 55nm or 80nm (or in the range of 50nm to 90 nm); and (b) positioning SUL 904 within the medium to provide a selected HUS such as a 120nm or 145nm (or in the range of 110nm to 150 nm) HUS. For example, the first SUL 904 may be configured by selecting or fabricating a material having a B _S above a B _S threshold, such as a B _S threshold of 1.2T (or a B _S threshold, e.g., in the range of 1.2T to 1.6T). The actual positioning of the first SUL 904 within the media to implement a particular HUS may depend on the HMS of the drive in which the media is to be installed. For example, if the HMS is fixed at 10nm, the first SUL 904 is positioned vertically within the media at a position relative to the top of the media to achieve a particular desired HUS, such as 120nm.

In some aspects, the second SUL 908 is configured and positioned by: (a) Configuring SUL 908 with a specific material having a high B _S, such as CoZrWMo, and having a specific SUL thickness, such as 25nm (or in the range of 20nm to 30 nm); and (b) positioning the SUL 908 within a medium to provide a selected HUS such as a 35nm (or in the range of 25nm to 35 nm) HUS. For example, the second SUL 908 may be configured by selecting or fabricating a material having a B _S that is higher than a B _S threshold, such as a B _S threshold of 1.2T (or a B _S threshold, e.g., in the range of 1.2T to 1.6T). As with the lower SUL 904, the location of the higher SUL 908 within the media that implements a particular HUS may depend on the HMS in which the drive of the media is to be installed. For example, if the HMS is fixed at 10nm, the SUL 908 is positioned at a location within the media relative to the top of the media to achieve a particular desired HUS, such as 35nm.

CoZrWMo are just one example of suitable materials for the SUL. Other soft magnetic materials may be used, such as one or more of Co, fe, ni and W, mo, ta, nb, cr, B, si or C, or combinations thereof. In some aspects, first SUL 904 and second SUL 908 may be made of CoZrWMo, coW, niFe or CoNiFe or a combination thereof. As described above, in some examples, the SUL is formed from Co or CoFe alloy with Zr, B, ta, W, mo additives (to make the layer soft magnetic and amorphous). In some aspects, first SUL 904 and second SUL 908 may be formed of different materials having different values of B _S.

In some aspects, the first SUL 904 and the second SUL 908 are configured and positioned to achieve a perpendicular magnetic field strength within the magnetic recording layer that is greater than an absolute amount of 7000 Oersted (and greater than 7500 Oersted when, for example, a write current Iw of 40mA is used, where Iw is a write current provided to a writer coil of a 3-turn writer for performing write operations. (see also fig. 7.)

In some aspects, the second SUL 908 is configured and positioned to increase the magnetic field strength within the magnetic recording layer of the medium by at least 10% during a write operation as compared to the magnetic field strength within a magnetic recording layer of a corresponding magnetic recording medium lacking the second SUL (e.g., the same magnetic recording medium except lacking the second SUL).

FIG. 10 is a schematic side view of an exemplary magnetic recording medium 1000 according to another aspect of the present disclosure. Medium 1000 has a stacked structure in which substrate 1002 has an adhesion layer 1004 directly on substrate 1002. The first (lower) SUL 1006 is located directly on the adhesion layer 1004. First SUL 1006 may be configured and positioned within magnetic recording medium 1000 to provide a first return path for magnetic flux from a magnetic recording head (not shown in FIG. 10) during a write operation. In other examples, the adhesion layer 1004 may be omitted, with the first SUL 1006 directly on the substrate 1002. Medium 1000 also has a heat sink layer 1008 directly on first SUL 1006. A second (higher) SUL 1010 is located on the heat sink layer 1008. The second SUL 1010 may be configured and positioned within the magnetic recording medium 1000 to provide a second return path for magnetic flux (from the magnetic recording head during a write operation) that is different from the first return path. MRL 1012 is located on a second SUL 1010. In some examples, second SUL 1010 is directly on heat sink layer 1008. In some examples, there are one or more additional layers, such as a seed layer, an MTO layer, and an MgO layer. For example, the seed layer may be directly on the second SUL, the MTO layer may be directly on the seed layer, and the MTO layer may be directly on the MgO layer, with the MRL directly on the MgO layer structure. In other examples, the seed layer includes an MTO layer and an MgO layer. The medium may be a HAMR medium. Other layers or films may also be provided as shown in fig. 3. Various layers or films may be formed using the various materials described above.

FIG. 11 is a schematic side view of an exemplary magnetic recording device 1100 including a magnetic recording head 1101 and a magnetic recording medium 1102, according to another aspect of the present disclosure. The medium 1102 has a structure stacked with the substrate 1104. A first (lower) SUL 1106 is located on a substrate 1104. In some examples, first SUL 1106 is directly on substrate 1104. In other examples, an intermediate adhesion layer is present. The first SUL 1106 has a top surface that is no more than 125nm from the bottom surface of the magnetic recording head 1101 while the magnetic recording head is positioned to write data to the magnetic recording medium, wherein the distance is taken from a point on the top surface of the first SUL that is directly below the write head (i.e., wherein a line perpendicular to the top surface at the point intersects the middle of the write head). The first SUL 1106 may have a thickness, for example, in the range of 55nm to 80 nm. Medium 1102 also has a heat sink layer 1108 located on first SUL 1106. In some examples, the heat sink layer 1108 is located directly on the first SUL 1106. A second (higher) SUL 1110 is located on the heat sink layer 1108. The second SUL 1110 has a top surface that is no more than 40nm from the bottom surface of the magnetic recording head while the magnetic recording head is positioned to write data to the magnetic recording medium, wherein the distance is taken from a point on the top surface of the second SUL that is directly below the write head (i.e., wherein a line perpendicular to the top surface at the point intersects the middle of the write head). The second SUL 1110 may have a thickness, such as 25nm, for example, in the range of 10nm to 30 nm. In some examples, second SUL 1110 is directly on heat sink layer 1108. MRL 1112 is located on second SUL 1110. In some examples, there are one or more additional layers, such as a seed layer, an MTO layer, and an MgO layer. For example, the seed layer may be directly on the second SUL, the MTO layer may be directly on the seed layer, and the MTO layer may be directly on the MgO layer, with the MRL directly on the MgO layer structure. In other examples, the seed layer includes an MTO layer and an MgO layer. The medium may be a HAMR medium. Other layers or films may also be provided as shown in fig. 3. Various layers or films may be formed using the various materials described above.

FIG. 12 is a flow chart of a process 1200 for manufacturing a magnetic recording medium according to some aspects of the present disclosure. In one aspect, process 1200 may be used to manufacture the media described above with respect to fig. 9. In block 1202, the process provides a substrate. In block 1204, the process provides an adhesion layer directly on the substrate. In block 1206, the process provides a first SUL located directly on the adhesion layer. In block 1208, the process provides a heat sink layer directly on the first SUL. In block 1210, the process provides a second SUL located on the heat sink layer. The second SUL may be located directly on the heat sink layer, but in some examples, there may be one or more intermediate layers. In block 1212, the process provides an MRL located on the second SUL. The MRL may be located directly on the second SUL, but in some examples, one or more intermediate layers may be present, such as MTO and MgO. For example, the process may provide a seed layer directly on the second SUL and a underlayer structure directly on the seed layer, the underlayer structure comprising a material selected from the group consisting of MgO and MgOTiO. The MRL may be disposed directly on the bedding structure. The medium manufactured may be a HAMR medium. In other examples, the adhesion layer is omitted and the first SUL is located directly on the substrate.

Additional aspects

Examples set forth herein are provided to illustrate certain concepts of the disclosure. The apparatus, devices, or components shown above may be configured to perform one or more of the methods, features, or steps described herein. Those of ordinary skill in the art will appreciate that these are merely exemplary in nature and that other examples may fall within the scope of the present disclosure and the appended claims. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Furthermore, other structures, functions, or structures and functions may be used in addition to or in place of one or more of the aspects set forth herein to implement such an apparatus or may practice such a method.

Aspects of the present disclosure have been described below with reference to schematic flow diagrams and/or schematic block diagrams of methods, apparatus, systems, and computer program products according to aspects of the present disclosure. It will be understood that each block of the schematic flow diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flow diagrams and/or schematic block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a computer or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor or other programmable data processing apparatus, create means for implementing the functions and/or acts specified in the schematic flow chart diagrams and/or schematic block diagram block or blocks.

The subject matter described herein may be implemented in hardware, software, firmware, or any combination thereof. As such, the terms "function," "module," and the like as used herein may refer to hardware, which may also include software and/or firmware components for implementing the described features. In one exemplary embodiment, the subject matter described herein can be implemented using a computer-readable medium having stored thereon computer-executable instructions that, when executed by a computer (e.g., a processor), control the computer to perform the functions described herein. Examples of computer readable media suitable for implementing the subject matter described herein include non-transitory computer readable media such as disk memory devices, chip memory devices, programmable logic devices, and application specific integrated circuits. Furthermore, a computer-readable medium embodying the subject matter described herein may be located on a single device or computing platform or may be distributed across multiple devices or computing platforms.

It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated figure. Although various arrow types and line types may be employed in the flow chart diagrams and/or block diagrams, they are understood not to limit the scope of the corresponding aspects. For example, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted aspect.

The various features and processes described above may be used independently of each other or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain methods, events, states, or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states associated therewith may be performed in other sequences as appropriate. For example, the described tasks or events may be performed in a different order than specifically disclosed, or multiple may be combined in a single block or state. Exemplary tasks or events may be performed in series, in parallel, or in some other suitable manner. Tasks or events may be added to or removed from the disclosed exemplary aspects. The exemplary systems and components described herein may be configured differently than described. For example, elements may be added, removed, or rearranged as compared to the disclosed exemplary aspects.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspect" does not require that all aspects include the discussed feature, advantage or mode of operation.

While the above description contains many specific aspects of the invention, these should not be construed as limitations on the scope of the invention, but rather as examples of specific aspects thereof. The scope of the invention should, therefore, be determined not with reference to the above-described aspects, but instead should be determined with reference to the appended claims along with their equivalents. Furthermore, reference throughout this specification to "one aspect," "an aspect," or similar language means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect of the present disclosure. Thus, the appearances of the phrases "in one aspect," "in an aspect," and similar language throughout this specification may, but do not necessarily, all refer to the same aspect, but mean "one or more but not all aspects," unless expressly specified otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms (i.e., one or more) as well, unless the context clearly indicates otherwise. The enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or inclusive, unless expressly specified otherwise. It will be further understood that the terms "comprises," comprising, "" includes, "" including, "" includes, "" having, "" has, "" with variations thereof, as used herein, mean "including but not limited to," unless expressly specified otherwise. That is, the terms may specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Furthermore, it should be understood that the word "OR" has the same meaning as the boolean operator "OR", that is to say that it encompasses the possibility of "OR" and "both", and is not limited to "exclusive OR" ("XOR") unless explicitly noted otherwise. It will also be appreciated that the symbol "/" between two adjacent words has the same meaning as "or" unless explicitly stated otherwise. Furthermore, phrases such as "connected to," "coupled to," or "in communication with" are not limited to direct connections unless specifically stated otherwise.

Any reference herein to elements using names such as "first," "second," etc. generally does not limit the number or order of those elements. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, reference to first and second elements does not mean that only two elements may be used there, or that the first element must somehow precede the second element. In addition, a set of elements may include one or more elements unless otherwise specified. Furthermore, as used in the specification or the claims, the term "at least one of a, b, or c" or "a, b, c, or any combination thereof" means "a or b or c or any combination of these elements. For example, this term may include a, or b, or c, or a and b, or a and c, or a and b and c, or 2a, or 2b, or 2c, or 2a and b, etc. As used in this disclosure, the term "about 'value X'" or "about value X" shall mean within 10% of "value X". For example, a value of about 1 or about 1 would mean a value in the range of 0.9-1.1. In one aspect, "about" as used herein may alternatively mean 5%. In the present disclosure, various numerical values are presented. It is contemplated that these values may have a tolerance of 10% unless specifically indicated otherwise. In another aspect, the tolerance may be 5%. In this disclosure, various value ranges may be specified, described, and/or claimed. It should be noted that any time the specification, description and/or claims specify, describe and/or claim a range is intended to include the endpoints (at least in one embodiment). In another embodiment, the range may not include the ends of the range. Various components described in this specification can be described as "comprising" or being made of certain materials or combinations of materials. In one aspect, this may mean that the component is composed of one or more specific materials. In another aspect, this may mean that the component comprises one or more specific materials.

As used herein, the term "determining" encompasses various actions. For example, "determining" may include arithmetic, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), determining or the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and so forth. Also, "determining" may include parsing, selecting, establishing, and the like.

Claims

1. A magnetic recording medium, the magnetic recording medium comprising:

A substrate;

A first Soft Underlayer (SUL) on the substrate, wherein the first SUL is configured and positioned within the magnetic recording medium to provide a first return path for magnetic flux;

a heat sink layer located on the first SUL;

A second SUL located on the heat sink layer, wherein the second SUL is configured and positioned within the magnetic recording medium to provide a second return path for magnetic flux that is different from the first return path; and

And a magnetic recording layer on the second SUL.

2. The magnetic recording medium of claim 1, wherein the first SUL and the second SUL each comprise a material having a saturation magnetic flux density greater than 1.2 tesla.

3. The magnetic recording medium of claim 1 wherein the first SUL and the second SUL each comprise CoZrWMo.

4. The magnetic recording medium of claim 1, wherein one or both of the first SUL and the second SUL comprises one or more of Co, fe, or Ni and W, mo, ta, nb, cr, B, si or C, or a combination thereof.

5. The magnetic recording medium of claim 1, wherein the first SUL and the second SUL are configured and positioned to achieve a perpendicular magnetic field strength having an absolute amount of more than 7000 oersted within the magnetic recording layer during a write operation.

6. The magnetic recording medium of claim 1, wherein the second SUL is configured and positioned to increase a magnetic field strength within the magnetic recording layer by at least 10% during a write operation as compared to a magnetic field strength within a magnetic recording layer of a corresponding magnetic recording medium without the second SUL.

7. The magnetic recording medium of claim 1 wherein the first SUL has a top surface that is about 110 nanometers (nm) from a top surface of the magnetic recording medium.

8. The magnetic recording medium of claim 1 wherein the first SUL has a top surface no greater than 120 nanometers (nm) from a top surface of the magnetic recording medium.

9. The magnetic recording medium of claim 1 wherein the second SUL has a top surface that is about 25 nanometers (nm) from a top surface of the magnetic recording medium.

10. The magnetic recording medium of claim 1 wherein the second SUL has a top surface no greater than 30 nanometers (nm) from a top surface of the magnetic recording medium.

11. The magnetic recording medium of claim 1, wherein the magnetic recording medium is configured for Heat Assisted Magnetic Recording (HAMR).

12. A data storage device, the data storage device comprising:

a slider including a magnetic write head; and

The HAMR medium of claim 11,

Wherein the slider is configured to write information to the magnetic recording layer of the HAMR medium during a write operation.

13. A magnetic recording medium, the magnetic recording medium comprising:

A substrate;

an adhesion layer directly on the substrate;

A first Soft Underlayer (SUL) directly on the adhesive layer;

A heat sink layer directly on the first SUL;

A second SUL located on the heat sink layer; and

And a magnetic recording layer on the second SUL.

14. The magnetic recording medium of claim 13 wherein the second SUL is directly on the heat sink layer.

15. The magnetic recording medium of claim 13, further comprising a seed layer directly on the second SUL, the seed layer configured to provide a growth template for subsequently deposited layers, wherein the magnetic recording layer is on the seed layer.

16. The magnetic recording medium of claim 15 wherein the seed layer comprises a material selected from the group consisting of MgO and MgO-TiO.

17. A magnetic recording apparatus, the magnetic recording apparatus comprising:

A magnetic recording head; and

A magnetic recording medium, the magnetic recording medium comprising:

A substrate;

A first Soft Underlayer (SUL) on the substrate, wherein the first SUL has a top surface no more than 125 nanometers (nm) from the magnetic recording head while the magnetic recording head is positioned to write data to the magnetic recording medium;

a heat sink layer located on the first SUL;

A second SUL located on the heat sink layer, wherein the second SUL has a top surface no more than 40nm from the magnetic recording head while the magnetic recording head is positioned to write data to the magnetic recording medium; and

And a magnetic recording layer on the second SUL.

18. A method for manufacturing a magnetic recording medium, the method comprising:

Providing a substrate;

providing an adhesion layer directly on the substrate;

Providing a first soft cushioning layer (SUL) directly on the adhesive layer;

providing a heat sink layer directly on the first SUL;

providing a second SUL located on the heat sink layer; and

A magnetic recording layer is provided on the second SUL.

19. The method of claim 18, further comprising:

Providing a seed layer directly on the second SUL; and

Wherein the magnetic recording layer is disposed directly on the seed layer.

20. The method of claim 18, wherein the first SUL and the second SUL each comprise CoZrWMo.