Cobalt-boron (CoB) layers for magnetic recording devices, memory devices, and memory devices

Abstract

Embodiments of the present disclosure relate to a cobalt-boron (CoB) layer for magnetic recording devices, memory devices, and memory devices. In one or more embodiments, the CoB layer is part of a spin-orbit torque (SOT) device. In one or more embodiments, the SOT device is part of an SOT-based sensor, an SOT-based writer, a memory device, such as a magnetoresistive random access memory (MRAM) device, and / or a storage device, such as a hard disk drive (HDD) or tape drive. In one embodiment, an SOT device includes a seed layer and a capping layer spaced apart from the seed layer. The SOT device includes a spin-orbit torque (SOT) layer, and a nanolayer (NL) between the seed layer and the capping layer. The SOT device includes a cobalt-boron (CoB) layer between the seed layer and the capping layer, and the CoB layer is ferromagnetic.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. non-provisional application No. 17 / 956,786, filed on September 29, 2022, entitled “Cobalt-Boron (CoB) Layer for Magnetic Recording Devices, Memory Devices, and Storage Devices,” and the entire contents of that U.S. non-provisional application are hereby incorporated by reference into this document for all purposes. Background Art Technical Field

[0003] Embodiments of the present disclosure relate to a cobalt-boron (CoB) layer for a magnetic recording device, a memory device, and a storage device.

[0004] Related technical description

[0005] In spin-orbit torque (SOT) devices, it may be desirable to have negative magnetostriction (λ), low coercivity (H c ), and high resistivity properties. However, many configurations have limitations in such properties. Many configurations may also involve obstacles regarding material melting, material migration, material damage, and large grain size.

[0006] Therefore, improved material configurations are needed, such as for SOT devices. Summary of the invention

[0007] Embodiments of the present disclosure relate to a cobalt-boron (CoB) layer for a magnetic recording device, a memory device, and a storage device. In one or more embodiments, the CoB layer is part of a spin-orbit torque (SOT) device. In one or more embodiments, the SOT device is part of a SOT-based sensor, a SOT-based writer, a memory device (such as a magnetoresistive random access memory (MRAM) device), and / or a storage device (such as a hard disk drive (HDD) or a tape drive).

[0008] In one embodiment, a spin-orbit torque (SOT) device includes a seed layer and a cover layer spaced apart from the seed layer. The cover layer is nonmagnetic. The SOT device includes a spin-orbit torque (SOT) layer and a nanolayer (NL) between the seed layer and the cover layer. The NL is magnetic. The SOT device includes a cobalt-boron (CoB) layer between the seed layer and the cover layer, and the CoB layer is ferromagnetic. The CoB layer is substantially free of materials other than cobalt (Co) and boron (B).

[0009] The NL is below the CoB layer and has a higher polarization than the CoB layer, which can increase the polarization of the CoB free layer (FL) layer (eg, polarize the CoB FL layer) and enhance the negative magnetostrictive property of the CoB layer.

[0010] In one embodiment, a spin-orbit torque (SOT) device includes a spin-orbit torque (SOT) layer comprising bismuth antimony (BiSb), and a cobalt-boron (CoB) layer. The CoB layer is ferromagnetic; the SOT device includes a nanolayer (NL) between the SOT layer and the CoB layer. The NL is magnetic. The SOT device includes one or more insertion layers, the one or more insertion layers are above the CoB layer, so that the CoB layer is between the NL and the one or more insertion layers.

[0011] In one embodiment, a spin-orbit torque (SOT) device includes a seed layer and a cover layer spaced apart from the seed layer. The cover layer is nonmagnetic. The SOT device includes a polarization device between the seed layer and the cover layer. The polarization device is magnetic. The SOT device includes a cobalt-boron (CoB) layer between the polarization device and the cover layer, and the CoB layer is ferromagnetic. The SOT device includes one or more insertion layers between the CoB layer and the cover layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Thus, a detailed understanding of the manner in which the above-described features of the present disclosure are understood, a more particular description of the present disclosure, the above brief overview, may be obtained by reference to the embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only typical embodiments of the present disclosure and are therefore not to be considered limiting of its scope, as the present disclosure may admit to other equally effective embodiments.

[0013] Figure 1 is a schematic diagram of a magnetic recording apparatus including a magnetic recording head having a SOT device according to one specific implementation.

[0014] Figure 2 is a schematic, fragmentary, cross-sectional side view of a read / write head having a SOT device according to one specific implementation.

[0015] FIG. 3A to FIG. 3C Schematic MFS views of a read head including a SOT device according to one or more specific implementations.

[0016] Figure 4A and Figure 4B is a schematic side view of a top spin-orbit torque (SOT) device according to one or more implementations.

[0017] Figure 5 is a schematic side view of a bottom SOT device according to a specific implementation.

[0018] Fig. 6A It shows the coercive force H c Schematic diagram of a graph comparing CoB free layer (FL) material thicknesses.

[0019] Figure 6B is a schematic diagram showing a graph of magnetostriction versus CoB (FL) material thickness.

[0020] Fig. 7A According to one specific implementation, in a MAMR write head, such as in a Figure 1 Schematic cross-sectional view of a SOT device for use in a MAMR write head that is a portion of a magnetic recording head of a magnetic recording device of FIG. 1 or other suitable magnetic recording device (e.g., a media drive).

[0021] FIG. 7B to FIG. 7C According to one or more specific implementations, Fig. 7A Schematic MFS view of a portion of a MAMR write head for a SOT device.

[0022] Figure 8 is a schematic cross-sectional view of a SOT magnetic tunnel junction (MTJ) used as an MRAM device.

[0023] Fig. 9 is a diagram showing a graph of magnetostriction (in ppm) of a CoB layer (FL) versus NL material thickness (in Angstroms).

[0024] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION

[0025] Hereinafter, reference is made to the embodiments of the present disclosure. However, it should be understood that the present disclosure is not limited to the embodiments specifically described. On the contrary, any combination of the following features and elements (whether or not related to different embodiments) is considered to realize and practice the present disclosure. In addition, although the embodiments of the present disclosure can achieve advantages that are superior to other possible solutions and / or superior to the prior art, whether a specific advantage is achieved by a given embodiment is not a limitation to the present disclosure. Therefore, the following aspects, features, embodiments and advantages are merely illustrative, and are not considered to be elements or limitations of the appended claims, unless explicitly stated in the claims. Similarly, reference to "the present disclosure" should not be interpreted as a summary of any inventive subject matter disclosed herein, and should not be considered to be elements or limitations of the appended claims, unless explicitly stated in the claims.

[0026] Embodiments of the present disclosure relate to a cobalt-boron (CoB) layer for a magnetic recording device, a memory device, and a storage device. In one or more embodiments, the CoB layer is part of a spin-orbit torque (SOT) device. In one or more embodiments, the SOT device is part of a SOT-based sensor, a SOT-based reader or writer, a memory device (such as a magnetoresistive random access memory (MRAM) device), and / or a storage device (such as a hard disk drive (HDD) or a tape drive). In one embodiment, the SOT device includes a seed layer and a cover layer spaced apart from the seed layer. The cover layer is non-magnetic. The SOT device includes a nanolayer (NL) between the seed layer and the cover layer, and the NL is magnetic. The SOT device includes a cobalt-boron (CoB) layer between the NL and the cover layer, and the CoB layer is ferromagnetic. The CoB layer contributes to negative magnetostriction (λ), low coercivity (H c ), and high resistivity. The CoB layer contributes to benefits such as enhanced recording performance, high signal-to-noise ratio, and / or reduced shunting.

[0027] The CoB layer can be part of a SOT device including a bismuth antimony (BiSb) layer (which can be used as a spin Hall layer). The SOT device may include a non-magnetic buffer layer, a non-magnetic interlayer, and a non-magnetic barrier layer. Therefore, a BiSb layer with a (012) orientation or a (001) orientation can form a SOT device. For example, a SOT device can be part of a write head (e.g., in a MAMR HDD) or a read head. In another example, the SOT device can be used in a nano-oscillator device for a read head application for detecting signals in the frequency domain. As another example, a SOT device can be used as part of an MRAM device (e.g., where the BiSb layer is used as a spin Hall electrode layer). The SOT device can be a vertically stacked configuration or an in-plane stacked configuration.

[0028] As such, SOT devices may be used, for example, in MAMR write heads, read heads, nano-oscillator-based readers, MRAM, artificial intelligence chips, and / or in other applications.

[0029] Unless otherwise specified, chemicals referred to herein can have any number of atoms of the included elements (eg, stoichiometric or non-stoichiometric).

[0030] Figure 1 is a schematic diagram of a magnetic recording device 100 including a magnetic recording head having a SOT device according to one specific implementation. Such a magnetic recording device may be a single drive or include multiple drives. Figure 1 In the illustrated implementation, the magnetic recording device 100 is a magnetic media drive, such as a hard disk drive (HDD). For ease of illustration, a single disk drive 100 is shown. As shown, at least one rotatable disk 112 is carried on a spindle 114 and is rotated by a drive motor 118. The magnetic recording on each disk 112 is in the form of any suitable pattern of data tracks, such as an annular pattern of concentric data tracks on the disk 112. The recording may also be in the form of any suitable pattern of servo tracks.

[0031] At least one slider 113 is positioned near the disk 112, and each slider 113 supports one or more head assemblies 121 including SOT devices. When the disk 112 rotates, the slider 113 moves radially in and out over the disk surface 122 so that the head assembly 121 can access different tracks of the disk 112 where desired data is written. Each slider 113 is attached to an actuator arm 119 via a suspension 115. The suspension 115 provides a slight spring force that biases the slider 113 toward the disk surface 122. Each actuator arm 119 is attached to an actuator member 127. As shown in FIG. Figure 2 The actuator device 127 shown may be a voice coil motor (VCM). A VCM comprises a coil that can move within a fixed magnetic field, the direction and speed of the coil movement being controlled by a motor current signal supplied by the control unit 129.

[0032] During operation of the disk drive 100, the rotation of the disk 112 creates an air bearing between the slider 113 and the disk surface 122, which exerts an upward force or lift on the slider 113. Thus, during normal operation, the air bearing counteracts the slight spring force of the suspension 115 and supports the slider 113 off and slightly above the disk surface 122 by a small, substantially constant spacing.

[0033] The various components of the disk drive 100 are controlled in operation by control signals (such as access control signals and internal clock signals) generated by a control unit 129. The control unit 129 may include logic control circuits, memory devices, and a microprocessor. The control unit 129 generates control signals that control various system operations, such as drive motor control signals on line 123 and head position and seek control signals on line 128. The control signals on line 128 provide the desired current distribution to optimally move and position the slider 113 to the desired data track on the disk 112. Write signals and read signals are transmitted to and from the write and read heads on the assembly 121 through the recording channel 125.

[0034] The above description of the magnetic recording device and Figure 1 The accompanying drawings are for illustrative purposes only. It should be apparent that the magnetic recording device may include a large number of media or disks and actuators, and each actuator may support multiple sliders. It should be understood that the embodiments discussed herein are applicable to data storage devices such as hard disk drives (HDDs) and tape drives, such as tape embedded drives (TEDs) or insertable tape media drives, such as those that comply with the LTO (Linear Tape Open) standard. An example TED is described in U.S. Application No. 16 / 365,034, filed on March 26, 2019, for a patent application entitled "Tape Embedded Drive," which is assigned to the same assignee of the present application and is incorporated herein by reference. Therefore, unless expressly claimed, any reference to an HDD or a tape drive in the specific embodiments is for illustrative purposes only and is not intended to limit the present disclosure. For example, references to disk media in HDD embodiments are provided only as examples and may be replaced with tape media in tape drive embodiments. Furthermore, claims referring to or involving magnetic recording devices or data storage devices are intended to include at least all HDDs, tape drives, and other magnetic recording devices unless a HDD or tape drive device is explicitly claimed.

[0035] Figure 2 1 is a schematic, fragmented, cross-sectional side view of a read / write head 200 having a SOT device according to one implementation. It should be noted that although the SOT device is shown in both the read head and the write head, this is for illustrative purposes, and in various implementations the SOT device may be independently integrated into only the read head or only the write head, or integrated into both the read head and the write head. The read / write head 200 faces the magnetic medium 112. The read / write head 200 may be used as Figure 1The magnetic head assembly 121 is shown and described in the drawings. The read / write head 200 includes a medium facing surface (MFS) 212 (such as a gas bearing surface (e.g., air bearing surface (ABS))) facing the magnetic disk 112, a write head 210, and a magnetic read head 211. Figure 2 As shown, the magnetic medium 112 moves past the write head 210 in the direction indicated by arrow 232 , and the read / write head 200 moves in the direction indicated by arrow 234 .

[0036] In one or more embodiments, the magnetic read head 211 is a SOT read head that includes a SOT sensing element 204 located between SOT shields S1 and S2. The magnetic field of adjacent magnetized regions in the disk 112 can be detected as a recorded bit by the SOT sensing element 204. In the SOT sensing element 204 including a BiSb layer, such as Figure 4A , Figure 4B and Figure 5 In the SOT device described in , the current flows perpendicular to the film plane, and the signal is read out by measuring the voltage generated by the reverse spin Hall effect in the BiSb layer. Various implementations of the SOT device can be incorporated into the read head 211 .

[0037] The write head 210 includes a main pole 220, a front shield 206, a rear shield 240, and a coil 218 for exciting the main pole 220. The coil 218 may have a "pancake" structure instead of Figure 2 The "helical" structure shown is a "pancake" structure that is wrapped around the back contact between the main pole 220 and the trailing shield 240. In one or more embodiments, the write head 210 is a perpendicular magnetic recording (PMR) write head. In one or more embodiments, the write head 210 can use energy-assisted magnetic recording (EAMR) technology, such as microwave-assisted magnetic recording (MAMR) and heat-assisted magnetic recording (HAMR).

[0038] exist Figure 2 In one or more embodiments, a spin-orbit torque (SOT) device 250 is shown as part of the write head structure to facilitate the MAMR recording effect. Figure 22 shows a SOT device for both the read head and the write head, but it is not necessarily required to implement the SOT device in both. The SOT device 250 is formed in the gap 254 between the main pole 220 and the tail shield 240. The main pole 220 includes a tail cone 242 and a front cone 244. The tail cone 242 extends from a recessed position in the MFS 212 to the MFS 212. The front cone 244 extends from a recessed position in the MFS 212 to the MFS 212. The tail cone 242 and the front cone 244 may have the same taper, and the taper is measured relative to the longitudinal axis 260 of the main pole 220. In one or more embodiments, the main pole 220 does not include the tail cone 242 and the front cone 244. Instead, the main pole 220 may include a tail side and a front side, and the tail side and the front side may be substantially parallel. The main pole 220 may be a magnetic material, such as a FeCo alloy. The front shield 206 and the tail shield 240 can be magnetic materials, such as NiFe alloys. In one or more embodiments, the tail shield 240 can include a tail shield thermal seed layer 241. The tail shield thermal seed layer 241 can include a high-torque sputtering material, such as CoFe, CoFeNi, or FeXN, where X includes at least one of Rh, Al, Ta, Zr, Co, and Ti. In some embodiments, the tail shield 240 does not include a tail shield thermal seed layer.

[0039] In one or more embodiments, the read head 211 is a spin torque oscillator (STO) read head having an STO oscillator sensing element 204 located between shields S1 and S2. The magnetic field of adjacent magnetized regions of the disk 112 can be detected as a recorded bit by the STO sensing element 204. The STO sensing element 204 includes a BiSb layer, such as Figure 4A , Figure 4B and Figure 5 SOT devices. The STO reader can operate in a 2-terminal or 3-terminal configuration, where an in-plane current flows inside the SOT structure while a small sense current flows perpendicular to the film plane, and the signal is read out by measuring the frequency of the precession of the magnetic layer. The SOT devices of various embodiments can be incorporated into the read head 211.

[0040] FIG. 3A to FIG. 3C Schematic MFS views of read heads 300, 350, 375 including a SOT device 301 having dual free layers 307a, 307b, respectively, according to one or more specific implementations. The read heads 300, 350, 375 may be used as Figure 2 The read head 211 of FIG.

[0041] Figure 3AThe read head 300 includes a first shield 302a, a first insulating layer 313a disposed on the first shield 302a, a first spin Hall effect layer (SHL) 310a disposed on the insulating layer 313a, a first free layer (FL) 307a disposed on the first SHL 310a, a gap layer 317 disposed on the first FL 307a, a second FL 307b disposed on the gap layer 317, a second SHL 310b disposed on the second FL 307b, a second insulating layer 313b disposed on the second SHL 310b, and a second shield 302b disposed on the second insulating layer 313b. The first SHL 310a and the second SHL 310b may each individually contain bismuth antimony (BiSb). The SHLs 310a and 310b may be referred to as spin-orbit torque (SOT) layers. The first FL 307a and the second FL 307b may each individually contain CoB, CoFeB, Co, CoFe, or NiFe. The first shield 302a and the second shield 302b may each individually include a magnetic material such as NiFe. The first insulating layer 313a and the second insulating layer 313b may each individually include an insulating material such as SiN or an oxide such as MgO, and may be formed with a Heusler alloy layer (hereinafter referred to as Figure 4A , Figure 4B ,and Figure 5 discussed in ) to maintain the texture and control the interdiffusion of Bi and Sb.

[0042] The side shield 319 is disposed adjacent to the SOT device 301 in the x-direction. The side shield 319 may include a magnetic material, such as NiFe. The third insulating layer 309 is disposed on the first SHL 310a and between the SOT device 301 and the side shield 319. The second SHL 310b is disposed in contact with the side shield 319. The antiferromagnetic cover layer 323 is disposed between the side shield 319 and the second insulating layer 313b. The first shield 302a and the second shield 302b, the first SHL 310a, and the Heusler alloy layer (hereinafter referred to as Figure 4A , Figure 4B ,and Figure 5 The first insulating layer 313a and the second insulating layer 313b used in combination with the first shield 302a (discussed in the foregoing) to control texture and interdiffusion may each individually have a greater length in the x-direction than the first FL 307a and the second FL 307b, the gap layer 317, and the second SHL 310b. The first current 321a flows from the first shield 302a into the gap layer 317, and the second current 321b flows from the gap layer 317 into the second shield 302b. A voltage may be applied to the first SHL 310a and the second SHL 310b.

[0043] Figure 3BThe read head 350 is similar to Figure 3A The read head 300 is provided. Figure 3B The read head 350 in FIG. 1 has no insulating layer or shield. In the read head 350, the first FL 307a is disposed on the first SHL 310a and includes the following: Figure 4A , Figure 4B ,and Figure 5 The interlayer of the Heusler alloy discussed in can be used in combination with a non-magnetic diffusion barrier between the FL 307a and the SHL layer 310a to reduce BiSb migration. The gap layer 317 is disposed on the first FL 307a, the second FL 307b is disposed on the gap layer 317, and the second SHL 310b is disposed on the second FL 307b, and a Heusler alloy (hereinafter referred to as in ) combined with a non-magnetic diffusion barrier layer can be used. FIG. 4A to FIG. 5 The first SHL 310a and the second SHL 310b may have a larger width in the x-direction than the first FL 307a and the second FL 307b and the gap layer 317. The first current 321a flows from the first SHL 310a into the gap layer 317, and the second current 321b flows from the gap layer 317 into the second SHL 310b. A voltage may be applied to the first SHL 310a and the second SHL 310b.

[0044] Figure 3C The read head 375 is similar to Figure 3A The read head 300 is provided. Figure 3C The read head 375 includes seed layers 325, 329 and interlayers 327a, 327b. The read head 375 includes a first shield 302a, a first insulating layer 313a disposed on the first shield 302a, a first seed layer 325 disposed on the insulating layer 313a, and a first SHL 310a disposed on the first seed layer 325. The read head 375 includes a first interlayer 327a disposed on the first SHL 310a, a first FL 307a disposed on the first interlayer 327a, a gap layer 317 disposed on the first FL 307a, a second seed layer 329 disposed on the gap layer 317, a second FL 307b disposed on the second seed layer 329, a second interlayer 327b disposed on the second FL 307b, a second SHL 310b disposed on the second interlayer 327b, a cap layer 323 disposed on the second SHL 310b, a second insulating layer 313b disposed on the second cap layer 323, and a second shield 302b disposed on the second insulating layer 313b. The cover layer 323 may include a migration barrier, such as a Heusler alloy layer (hereinafter FIG. 4A to FIG. 5), the migration barrier is optionally combined with an additional non-magnetic migration barrier adjacent to BiSb to control Bi, Sb migration. In one or more embodiments, each layer of the read head 375 has the same length in the x-direction. The present disclosure also contemplates that the layers of the read head 375 may have varying lengths in the x-direction.

[0045] The capping layer 323 comprises a material selected from the group consisting of SiN, TiN, Al2O3, SiO2, NiFeTa, NiTa, NiW, NiFeW, CoHf, CoFeHf, Pt, Co, Cu, Ni, NiCu, CoCu, Ru, Ta, Cr, Au, Rh, other non-magnetic materials, and combinations thereof. The first seed layer 325 comprises a silicide or GeNiFe layer optionally in combination with another non-magnetic barrier. The second seed layer 329 may comprise a GeNiFe layer optionally in combination with another non-magnetic barrier. The first interlayer 327a and the second interlayer 327b may each individually comprise a non-magnetic Si or Ge transition metal alloy layer (such as a NiFeGe or CoFeGe layer), a Heusler alloy layer, or other alloy, in combination with a material selected from the group consisting of Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B or in combination with another non-magnetic barrier to control BiSb intermixing and maintain BiSb texture.

[0046] Although FIG. 3A to FIG. 3C Each dual ferromagnetic or dual free layer SOT device 301 is shown separately, but FIG. 3A to FIG. 3C The read heads 300, 350, 375 may alternatively utilize a single ferromagnetic or single free layer SOT device or a single ferromagnetic or single free layer SOT device including an antiferromagnetic (AFM) layer, wherein the AFM layer may include a single layer or multiple layers of PtMn, NiMn, IrMn, IrMnCr, CrMnPt, FeMn, other antiferromagnetic materials, and / or combinations thereof. An exemplary single ferromagnetic or single free layer SOT device may include a substrate or shield, a buffer layer disposed on the substrate, a free layer disposed on the buffer layer, an interlayer disposed on the free layer, a SHL disposed on the interlayer, and a capping layer disposed on the SHL. An exemplary single ferromagnetic or single free layer SOT device including an AFM layer may include an AFM layer disposed adjacent to the single ferromagnetic or single free layer SOT device, wherein the AFM layer is recessed from the MFS. Additionally, the described single or dual free layer based SOT devices may be used in magnetic sensor applications other than read sensors / readers in magnetic recording, and such sensors may be similarly fabricated into the various reader stacks shown or described.

[0047] Figure 4A and Figure 4Bis a schematic side view of a top spin-orbit torque (SOT) device 400 , 450 according to one or more implementations.

[0048] Figure 5 is a schematic side view of a bottom SOT device 500 according to a specific implementation.

[0049] Each of the SOT devices 400, 450, 500 may include FIG. 4A to FIG. 5 The SOT devices 400, 450, 500 can each be used individually Figure 1 The magnetic recording device 100 or other suitable magnetic recording device has a magnetic recording head, such as Figure 2 The read head 211 and / or the write head 210, and FIG. 3A to FIG. 3C One or more of the read heads 300, 350, 375. For example, Figure 3C The first seed layer 325 and the second seed layer 329 and the first interlayer 327a and the second interlayer 327b may be the first insertion layer 416, the second insertion layer 417, and / or the NL 412 discussed below. FIG. 4A to FIG. 5 Various SOT devices / stacks can be used for magnetic sensors and as MRAM (such as Figure 8 A portion of the memory structure in the example shown in ).

[0050] In addition, although the SOT devices 400, 450, 500 are referred to as SOT devices, the SOT devices 400, 450, 500 can each be used individually as a spin torque oscillator (STO) device. Aspects of each SOT device 400, 450, 500 can be used in combination with each other. When the SOT device 400, 450, 500 is used in a write head, current flows in a plane to the SOT layer or bismuth antimony (BiSb) layer 410, and the ferromagnetic (FM) or free layer oscillates through the SOT generated by the spin Hall effect in the BiSb layer 410.

[0051] Figure 4AThe SOT device 400 includes a first electrode 402a, a seed layer 404 disposed on the first electrode 402a, an optional buffer layer 406 disposed on the seed layer 404, an optional nucleation layer 408 disposed on the buffer layer 406, a BiSb layer 410 disposed on the optional nucleation layer 408 (or the buffer layer 406), an optional spacer 411 disposed on the BiSb layer 410, a nanolayer (NL) 412 disposed on the optional spacer 411 (or the BiSb layer 410), a cobalt-boron (CoB) layer 414 disposed on the NL 412, one or more insertion layers 416, 417 disposed on the CoB layer 414, a capping layer 418 disposed on the one or more insertion layers 416, 417, and a second electrode 402b disposed on the capping layer 418. The second electrode 402b is spaced apart from the first electrode 402a using layers 404, 406, 408, 410, 412, 414, 416, 417, 418 between the first electrode 402a and the second electrode 402b. Although shown, the first electrode 402a and the second electrode 402b are optional.

[0052] The capping layer 418 is spaced apart from the seed layer 404, and the capping layer 418 is nonmagnetic. Each of the layers 406, 408, 410, 412, 414, 416, 417 is between the seed layer 404 and the capping layer 418. The NL 412 is magnetic. The CoB layer 414 is between the NL 412 and the capping layer 418, and the CoB layer 414 is ferromagnetic. One or more insertion layers 416, 417 are between the CoB layer 414 and the capping layer 418. The present disclosure contemplates that the majority of the phase of each of the layers 404, 406, 408, 410, 411, 412, 414, 416, 417, 418 can be crystalline, amorphous, or nanocrystalline.

[0053] In one or more embodiments, NL 412 is formed of a magnetic material that includes one or more of cobalt (Co), nickel-iron (NiFe), cobalt-iron (CoFe), and / or Heusler alloy. In one or more embodiments, the magnetic material of NL 412 includes Co2FeGe. In one or more embodiments, the magnetic material of NL 412 includes CoFeX, where X is an element that does not easily interact with BiSb, such as Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B. In such embodiments, NL 412 can have negative magnetostriction. In one or more embodiments, NL 412 is formed of Co or CoFe with an Fe atomic percentage in the range of 5% to 60% (such as 5%, 10%, 25%, or 60%) and a Co atomic percentage in the range of 35% to 90%. In one or more embodiments, the Fe atomic percentage is in the range of 10% to 60%. The Co atomic percentage and the Fe atomic percentage added together equal at least 95% of the total atomic percentage of NL 412.

[0054] In one or more embodiments, a majority of the phase of the CoB layer 414 is amorphous. The boron (B) atomic percentage of the CoB layer 414 is in the range of 5% to 30%, and the cobalt (Co) atomic percentage of the CoB layer 414 is in the range of 65% to 90%. In one or more embodiments, the B atomic percentage is in the range of 10% to 30%. In one or more embodiments, the B atomic percentage is about 20%. The B atomic percentage and the Co atomic percentage add up to at least 95% of the total atomic percentage of the CoB layer 414. In this specific implementation, the CoB layer 414 is substantially free of other materials (such as nickel (Ni) and iron (Fe)). For example, other materials may be present in the CoB layer 414 at a total atomic percentage of 5% or less (such as 4% or less).

[0055] The first thickness T1 (in the downstream direction) of the CoB layer 414 is at least 35 angstroms, such as 40 angstroms or more. In one or more embodiments, the first thickness T1 is in the range of 50 angstroms to 100 angstroms. The first thickness T1 promotes, for example, negative magnetostriction. The second thickness T2 of the NL 412 is 5 angstroms or less. In one or more embodiments, the second thickness T2 is 3.5 angstroms or less, or 2.0 angstroms or less. The second thickness T2 can promote sufficient magnetic coupling of the CoB layer 414 with the BiSb layer 410. The present disclosure contemplates that a portion of the CoB layer 414 can migrate (e.g., leach) out toward the NL 412.

[0056] The ratio of the first thickness T1 to the second thickness T2 is 9:1 or higher, such as 12:1 or higher.

[0057] The third thickness T3 of the capping layer 418 is 100 angstroms or less. In one or more embodiments, the third thickness T3 is 50 angstroms or less, such as in the range of 15 angstroms to 50 angstroms. The resistivity of the CoB layer 414 is at least 100 μOhms-cm. In one or more embodiments, the resistivity of the CoB layer 414 is in the range of 120 μOhms-cm to 140 μOhms-cm or more, such as 140 μOhms-cm or more, or 150 μOhms-cm or more. In one or more embodiments, the thickness of each of the spacer 411, NL412, the first insertion layer 416, the second insertion layer 417, and the capping layer 418 is less than 50 angstroms. The coercivity of the CoB layer 414 is less than 10 Oe, such as 8 Oe or less, 7 Oe or less, or 6 Oe or less.

[0058] The CoB layer 414 promotes low coercivity, reduced shunting of magnetic (e.g., read) signals, negative magnetostriction, and high resistivity. The CoB layer 414 promotes benefits such as high spin Hall effect, enhanced recording performance, and / or high signal-to-noise ratio. The use of the CoB layer 414 and the NL 412 promotes negative magnetostriction and increased spin polarization and increased signal amplitude of the SOT device 400.

[0059] The one or more insertion layers 416, 417 include a first insertion layer 416, and a second insertion layer 417 between the first insertion layer 416 and the capping layer 418. In one or more embodiments, the first insertion layer 416 is formed of hafnium (Hf) and the second insertion layer 417 is formed of tantalum (Ta). Each of the first insertion layer 416 and the second insertion layer 417 has a thickness T4, T5 in the range of 10 angstroms to 15 angstroms. Other materials are contemplated for the insertion layers 416, 417. The insertion layers 416, 417 facilitate controlling magnetostriction while helping the capping layer 418 protect the layers of the SOT device 400 from environmental factors.

[0060] The optional spacer layer 411, if used, is a highly resistive and nonmagnetic layer and may (1) be formed of Fe, Co, or a magnetic alloy such as NiFe, CoFe, which in turn is alloyed with relatively non-SOT intermixed elements such as Cu, Ag, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B to form an amorphous nonmagnetic layer, or (2) may be formed of a non-interacting highly resistive layer such as, but not limited to, an oxide such as TiO, a nitride such as TiN, and / or a boride such as TiB and / or ZrB. The optional spacer layer 411 may be similar to the first interlayer 327a and / or the second interlayer 327b of the read head 375.

[0061] Figure 4BThe SOT device 450 shown is similar to Figure 4A The SOT device 400. The SOT device 450 also includes a texture layer 452 disposed between the seed layer 404 and the buffer layer 406, and the NL 412 is disposed on the interlayer 454 disposed on the BiSb layer 410. Therefore, the SOT device 450 includes the seed layer 404, the texture layer 452 disposed on the seed layer 404, the buffer layer 406 disposed on the texture layer 452, the optional nucleation layer 408 disposed on the buffer layer 406, the BiSb layer 410 disposed on the optional nucleation layer 408 or the buffer layer 406, the interlayer 454 disposed on the BiSb layer 410, the NL 412 disposed on the interlayer 454, the CoB layer 414 disposed on the NL 412, the first insertion layer 416 disposed on the CoB layer 414, the second insertion layer 417 disposed on the first insertion layer 416, and the capping layer 418 disposed on the second insertion layer 417. Although in Figure 4B 4. Although not shown, the SOT device 450 may include a first electrode 402a and a second electrode 402b outside the seed layer 404 and the cap layer 418. The texture layer 452 may include RuAl, CrMo, or multiple layers of CrMoX with CrX (where X = Ti, Ru, Mo, or W). In one or more embodiments, the interlayer 454 is non-magnetic.

[0062] Figure 5 The SOT device 500 shown in FIG. FIG. 4A to FIG. 4B The SOT devices 400 and 450 are shown in FIG. 5 , except that the SOT device 500 is in a bottom configuration instead of FIG. 4A to FIG. 4B For the SOT device 500 , the CoB layer 414 is disposed below the BiSb layer 410 . Figure 5 The SOT device 500 shown includes a seed layer 404, a texture layer 452 disposed on the seed layer 404, a CoB layer 414 disposed on the texture layer 452, an NL 412 disposed on the CoB layer 414, a buffer layer 406 disposed on the NL 412, a BiSb layer 410 disposed on the buffer layer 406, a barrier layer 512 disposed on the BiSb layer 410, and a cap layer 418 disposed on the barrier layer 512. Figure 5402a and 402b and / or the nucleation layer 408. In one or more embodiments, the barrier layer 512 is a crystalline high-resistance layer and contains zirconium nitride (ZrN) and / or titanium nitride (TiN). In one or more embodiments, the barrier layer 512 is a non-magnetic and amorphous high-resistance layer and can be similar to the first interlayer 327a and / or the second interlayer 327b. The barrier layer 512 can be formed of a non-interacting high-resistance layer such as an oxide (such as TiO), a nitride (such as TiN), and / or a boride (such as TiB and / or ZrB). The barrier layer 512 can facilitate reducing shunting from the cap layer 418 to the BiSb layer 410.

[0063] For the SOT devices 400, 450, 500, the BiSb layer 410 may be FIG. 3A to FIG. 3C The BiSb layer 410 may have a thickness of about 100 mm in the y direction (eg, along the downward direction). to about The thickness T6 is within the range. The BiSb layer 410 may be referred to herein as a spin Hall effect (SHE) layer, a spin-orbit torque (SOT) layer, or a topological insulator. The BiSb layer 410 may include undoped BiSb or doped BiSbX, wherein the atomic percentage of the dopant is less than about 10%, and wherein X is extracted from an element that does not interact easily with Bi or Sb, such as Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B or an alloy combination of one or more of the foregoing elements, such as CuAg, CuNi, CoCu, AgSn. The BiSb layer 410 may have a (012) crystal orientation or a (001) crystal orientation.

[0064] In embodiments where the SOT device 400, 450, 500 includes a first electrode 402a and a second electrode 402b, the first electrode 402a and the second electrode 402b may each individually comprise a non-magnetic low resistivity metal. For example, the first electrode 402a and the second electrode 402b may each comprise Ru, CuAg, Ta(α), W(α), Mo, Cu, Ag, Rh, Pt, etc. If the first electrode 402a and the second electrode 402b are far enough away so as not to interfere with the FM / SOT interaction, a magnetic material with low to medium resistivity may be used. The thickness of each of the first electrode 402a and the second electrode 402b in the y direction is greater than or equal to about

[0065] Figure 4A , Figure 4B and Figure 5 The SOT devices 400, 450, 500 can each be used as FIG. 3A to FIG. 3C The SOT device 301 of each read head 300, 350, 375.

[0066] As further described below, the present disclosure contemplates a variety of properties, materials, features, components, and / or aspects of SOT devices 400, 450, 500 and their layers. Such properties, materials, features, components, and / or aspects may be used to replace (or supplement) certain properties, materials, features, components, and / or aspects described above.

[0067] The texture layer 452 may include RuAl (where Ru is in the range of about 45% to about 55% by atomic percentage), CrMo (where Mo is in the range of about 25% to about 50% by atomic percentage), or multiple layers of CrMoX with CrX (where X=Ti, Ru, Mo, or W). The texture layer 452 has a (001) texture. The texture layer 452 may have a B2 or BCC crystal structure, where the a-axis lattice parameter is about 2.95 angstroms to about 3.05 angstroms. The thickness of the texture layer 452 in the y direction is about 30 angstroms to about 50 angstroms.

[0068] Each of the buffer layer 406, NL 412, interlayer 454, first insertion layer 416, second insertion layer 417, and / or nucleation layer 408 may include a magnetic or non-magnetic Heusler alloy, wherein the Heusler alloy may be a full Heusler alloy (i.e., X2YZ) or a half Heusler alloy (i.e., XYZ). Full X2YZ-type Heusler alloys typically have L21, cF16, B2-type structures, with a-axis lattice parameters ranging from about 5.70 angstroms to about 6.20 angstroms, which may match embodiments in which the texture layer 452 has RuAl or CrMo. Half XYZ-type Heusler alloys typically have C1b-type or Pm-3m-type structures, with a-axis lattice parameters ranging from about 2.85 angstroms to about 3.10 angstroms. However, the type or structure may vary with respect to half Heusler alloys and full Heusler alloys. For example, RuMnAl, RhMnAl, and Al2CuRh have a Pm-3m structure, and Ni2MnAl and Mn2NiAl have a cF16 structure, and Al2NiMn has a B2 structure.

[0069] For full and half Heusler alloys, X can be one of Li, Mg, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Cd, Ir, Pt, or Au; Y can be one of Li, Be, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Mo, Hf, or W; and Z can be one of B, Mg, Al, Si, Zn, Ga, Ge, As, In, Sn, Sb, Pb, or Bi. Some examples of nonmagnetic Heusler alloys include Ti2MnAl, Fe2VAl (a-axis = 5.78 angstroms), Cr2CoAl (a-axis = 5.88 angstroms), CoTiSb (a-axis = 5.88 angstroms), Mn2VSi, V2VAl (a-axis = 6.14 angstroms), [Mn 1-x Co x ]2VAl(x=0.5)(a-axis=6.05 Å), [Mn 1-x Co x ]2VSi (x = 0.25) (a axis = 6.18 angstroms), and CoMnNbAl, CoZrFeAl. Examples of magnetic Heusler alloys with large spin polarization include Co2MnSb (a axis = 5.94 angstroms), Co2MnGe (a axis = 5.75 angstroms), CoMnSb (a axis = 5.90 angstroms) NiMnSb, Co2FeGe, Co2MnSn, and Co2MnFeGe, each of which is not easily mixed with the BiSb layer 410.

[0070] Each of the buffer layer 406, NL 412, interlayer 454, first insertion layer 416, second insertion layer 417, and / or nucleation layer 408 may include: (1) an amorphous / nanocrystalline layer formed by combining a Heusler alloy with an element, or an alloy layer that is not easily mixed with a SOT or NL layer, or a uniform alloy formed by co-sputtering a Heusler alloy with other elements, or an alloy that is not easily mixed with a SOT or NL layer, or (2) a polycrystalline Heusler alloy as an epitaxial layer in the SOT device 400, 450, 500. With respect to the amorphous / nanocrystalline buffer layer 406, the nucleation layer 408, the NL 412, and the insertion layers 416, 417, thin polycrystalline Heusler alloys (magnetic and non-magnetic, and full or half Heusler alloys) may be used when alloyed with other elements that do not readily mix with the BiSb layer 410, such as Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B, or alloy combinations of one or more of the foregoing elements (such as CuAg, CuNi, CoCu, AgSn). The nucleation layer 408 may also be a very thin (e.g., dusting) layer of these aforementioned elements or very thin alloy combinations of these elements (e.g., CuAg, CuNi, CoCu, and / or AgSn).

[0071] In one or more embodiments, the nonmagnetic amorphous / nanocrystalline buffer layer 406 and the nucleation layer 408 are effectively formed using an amorphous or nanocrystalline layer formed from a Heusler alloy alloyed with other elements that are not miscible with the BiSb layer 410 in the following situations: (1) after deposition and room temperature (RT) intermixing; (2) post-annealing before deposition of the BiSb layer 410; (3) in a single uniform composition layer, depositing the nonmagnetic amorphous / nanocrystalline alloy using a single alloy target; or (4) co-sputtering with a target containing an element of the Heusler alloy and an immiscible multi-element combination of the above elements.

[0072] In one or more embodiments, NL 412, interlayer 454, first insertion layer 416, and / or second insertion layer 417 are formed in a manner similar to buffer layer 406 and nucleation layer 408 (although nucleation layer 408 may also be only the above-mentioned elements or any non-magnetic alloy combination of these elements); however, after deposition and room temperature (RT) intermixing, the resulting graded NL 412, interlayer 454 or insertion layer 416, 417 does not have to be amorphous, as long as the resulting layer has high resistance and reduces the intermixing of NL412 / interlayer 454 / insertion layer 416, 417 with the BiSb layer 410 or with the CoB layer 414.

[0073] Magnetic alloys and magnetic Heusler alloys may be used in combination with other elements or alloys described above so that when deposited, the materials intermix at room temperature or after post-annealing to form a stack (which may be magnetic or non-magnetic). Examples include layers of NiFeX, CoFeX, NiX, FeX, CoX, where X is an element that does not interact readily with BiSb, such as Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B, and / or a magnetic Heusler alloy deposited on a non-interacting element or alloy layer (e.g., a Ge layer) and in a single alloy deposited layer, wherein the resulting Ge content in the intermixed alloy can make the intermixed alloy nonmagnetic for interlayer 454 (e.g., in the case of alloying with Ge, the Ge content can be greater than or equal to about 44 atomic percent); or combined with a sufficiently thick layer of an element that does not interact readily with BiSb (such as Cu, Ag, Si, Ge, Mn, Ni, Co, Mo, W, Ti, and / or B) to form a multi-element high resistivity combination thereof; or a single polycrystalline nonmagnetic Heusler layer.

[0074] Another example of a material that can be used for the interlayer 454 / NL 412 stack includes: Ge / CoFe / NiFeTaN (where Ge / CoFe can form a single layer at room temperature or can be deposited as an alloy layer).

[0075] NL 412 may include a magnetic material such as a polycrystalline magnetic Heusler alloy. Magnetic Heusler alloys have large spin polarizations, and examples of magnetic Heusler alloys that may be used in NL 412 include Co2MnSb, Co2MnGe, CoMnSb, NiMnSb, Co2FeGe, Co2MnSn, and Co2MnFeGe, which do not readily mix with BiSb layer 410.

[0076] In one or more embodiments, NL 412 is crystalline and formed from highly polarized Heusler layers.

[0077] It should be further understood that multiple SOT devices 400 can be configured together as part of a memory cell array, wherein the BiSb layer 410 is a spin-track material electrode, wherein the top electrode 402b can be disposed above the cap layer 418; and multiple SOT devices 450 can be configured together as part of a memory cell array, wherein the BiSb layer 410 is a spin-track material electrode, wherein the top electrode (not shown) can be disposed above the cap layer 418; and multiple SOT devices 500 can be configured together as part of a memory cell array, wherein the BiSb layer 410 is a spin-track material electrode, wherein the top electrode can be disposed above the cap layer 418. Each of the memory cells can be part of a two-terminal device or a three-terminal device. The spin-track material electrode and the top electrode can be used as a bit line, a word line, a read word line, a write word line, and combinations thereof. The memory cell array can be implemented as a cross-point array or other architectures.

[0078] As mentioned above, FIG. 4A to FIG. 5 Each of the SOT devices 400, 450, and 500 can be used as a BiSbSTO device. BiSb-based STO devices, such as FIG. 4A to FIG. 5 The SOT devices 400, 450 and 500 of the present invention generally have a larger SHA than other STO-based devices at the same input current density. Therefore, the BiSb-based STO devices used in the read head have high performance. The present disclosure contemplates that other materials (other than BiSb) can be used for the SOT layer 410.

[0079] Fig. 6A It shows the coercive force H c Schematic diagram of a graph 600 comparing CoB free layer (FL) material thicknesses.

[0080] Figure 6B is a schematic diagram of a graph 650 showing magnetostriction versus CoB FL material thickness.

[0081] The first line 610 fitted to the data points shows that as the material thickness increases, the coercivity increases. The second line 620 fitted to the data points shows that as the material thickness increases, the magnetostriction becomes negative. Therefore, negative magnetostriction can be associated with higher coercivity and / or lower resistivity (which can hinder device performance).

[0082] Using specific implementations of the present disclosure, negative magnetostriction, lower coercivity, and higher resistivity are all facilitated at relatively low material thicknesses.

[0083] Fig. 7A According to one specific implementation, in a MAMR write head, such as in a Figure 1 Schematic cross-sectional view of a SOT device 700 for use in a MAMR write head that is a portion of a magnetic recording head of a magnetic recording device 100 or other suitable magnetic recording device (e.g., a media drive). The SOT device 700 includes a doped BiSb layer 410 having a (001) orientation or alternatively an undoped BiSb layer 410 having a (012) orientation, the BiSb layer being formed over a buffer layer 406 (or nucleation layer 408), formed over a shield or substrate 402, such as FIG. 4A to FIG. 5 The buffer layer 406 may include the BiSb layer 410 as described above. FIG. 4A to FIG. 5 The CoB layer 414 is formed on the BiSb layer 410. The CoB layer 414 may be referred to as a spin torque layer (STL). As described above, the CoB layer 414 includes a ferromagnetic material, such as one or more layers of CoB and / or Co. The CoB layer 414 may be a free layer, such as FIG. 3A to FIG. 3C Therefore, the CoB layer 414 may be referred to as a free layer.

[0084] In one or more embodiments, the current shunt blocking layer 760 is disposed between the BiSb layer 410 and the CoB layer 414. The current shunt blocking layer 760 reduces the current flowing from the BiSb layer 410 to the CoB layer 414, but allows spin-orbit coupling of the BiSb layer 410 and the CoB layer 414. In one or more embodiments, the current shunt blocking layer 760 includes a magnetic material that provides greater spin-orbit coupling between the BiSb layer 410 and the CoB layer 414 than a non-magnetic material. In one or more embodiments, the current shunt blocking layer 760 comprises FeCo, FeCoM, FeCoMo, FeCoMMeO, FeCoM / MeO stack, FeCoMNiMnMgZnFeO, FeCoM / NiMnMgZnFeO stack, multiple layers / stacks thereof, or combinations thereof, wherein M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr. In certain embodiments, the current shunt blocking layer 760 is formed to about to about In some aspects, the thickness of The current shunt blocking layer 760 having a thickness of less than 100 nm can reduce the spin-orbit coupling of the BiSb layer 410 and the CoB layer 414. In some aspects, the current shunt blocking layer 760 having a thickness of less than 100 nm can reduce the spin-orbit coupling of the BiSb layer 410 and the CoB layer 414. A current-diverting blocking layer having a thickness of 100 Å may not sufficiently reduce the current from the BiSb layer 410 to the CoB layer 414 .

[0085] In one or more embodiments, additional layers such as a spacer 780 and a pinning layer 790 are formed over the CoB layer 414. The pinning layer 790 can partially pin the CoB layer 414. The pinning layer 790 can include a single layer or multiple layers of PtMn, NiMn, IrMn, IrMnCr, CrMnPt, FeMn, other antiferromagnetic materials, or combinations thereof. The spacer 780 includes a single layer or multiple layers of magnesium oxide, aluminum oxide, other non-magnetic materials, or combinations thereof.

[0086] FIG. 7B to FIG. 7C According to one or more specific implementations, Fig. 7A Schematic MFS view of a portion of a MAMR write head 210 of a SOT device 700. The MAMR write head 210 may be Figure 2 The write head in the Figure 1The MAMR write head 210 includes a main pole 220 and a trailing shield 240 in the downtrack direction. The SOT device 700 is disposed in a gap between the main pole 220 and the trailing shield 240.

[0087] During operation, a charge current through the BiSb layer or layer stack 410 as a spin Hall layer generates a spin current in the BiSb layer. The spin-orbit coupling of the BiSb layer and the CoB layer 414 (spin torque layer (STL)) causes switching or precession of the magnetization of the CoB layer 414 through spin-orbit coupling of the spin current from the BiSb layer 410. The switching or precession of the magnetization of the CoB layer 414 can generate an auxiliary alternating current (AC) electric field to the write field. Compared with the MAMR write head based on spin transfer torque, the energy-assisted write head based on SOT has several times greater power efficiency. As Figure 7B As shown, due to the shape anisotropy of the CoB layer 414 and due to Fig. 7A Due to the pinned layer 790 and / or the hard bias element near the STL 414, the easy axis of the magnetization direction of the CoB layer 414 is perpendicular to the MFS. Figure 7C As shown, due to the shape anisotropy of the CoB layer 414 and due to Fig. 7A The easy axis of the magnetization direction of the STL 770 is parallel to the MFS due to the pinned layer 790 and / or due to the hard bias element close to the CoB layer 414.

[0088] Figure 8 8 is a schematic cross-sectional view of a SOT magnetic tunnel junction (MTJ) 801 used as an MRAM device 800. The SOT MTJ 801 may involve a tunnel magnetoresistance (TMR). The MRAM device 800 includes a reference layer (RL) 810, a spacer 820 above the RL 810, a recording layer 830 above the spacer 820, a buffer layer 406 (or nucleation layer 408) above a current shunt blocking layer 840 above the recording layer 830, a BiSb layer or layer stack 410 above the buffer layer 406, and a CoB layer 414 above the BiSb layer or layer stack 410. The BiSb layer 410 may be FIG. 4A to FIG. 5 The buffer layer 406 may include the BiSb layer 410 as described above. FIG. 4A to FIG. 5 and have the same or similar properties as described above with respect to various embodiments. The BiSb layer 410 may be a doped BiSb layer having a (012) orientation or an undoped BiSb layer having a (001) orientation. The RL 810 may be a free layer such as FIG. 3A to FIG. 3C Therefore, the RL 810 may be referred to as a free layer.

[0089] RL 810 includes a single layer or multiple layers of CoFe, other ferromagnetic materials, and / or combinations thereof. Interlayer 820 includes a single layer or multiple layers of magnesium oxide, aluminum oxide, other dielectric materials, and / or combinations thereof. Recording layer 830 includes a single layer or multiple layers of CoFe, NiFe, other ferromagnetic materials, and / or combinations thereof.

[0090] As described above, in certain embodiments, the current shunt blocking layer 840 is disposed between the buffer layer 406 and the recording layer 830. The current shunt blocking layer 840 reduces the current flowing from the BiSb layer 410 to the recording layer 830, but allows spin-orbit coupling of the BiSb layer 410 and the recording layer 830. For example, writing to an MRAM device can be facilitated by spin-orbit coupling of the BiSb layer and the recording layer 830, which facilitates switching of the magnetization of the recording layer 830 by spin-orbit coupling of a spin current from the BiSb layer 410. In one or more embodiments, the current shunt blocking layer 840 includes a magnetic material that provides greater spin-orbit coupling between the BiSb layer 410 and the recording layer 830 than a non-magnetic material. In one or more embodiments, the current shunt blocking layer 840 comprises FeCoM, FeCoMo, FeCoMMeO, a FeCoM / MeO stack, a FeCoMNiMnMgZnFeO, a FeCoM / NiMnMgZnFeO stack, multiple layers / stacks thereof, and / or combinations thereof, wherein M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and / or Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr.

[0091] Figure 8 The MRAM device 800 may include other layers, such as a pinning layer, a pinning structure (e.g., a synthetic antiferromagnetic (SAF) pinning structure), an electrode, a gate, and / or other structures. The MRAM device 800 may be formed using an undoped BiSb layer 410 having a (001) orientation or an alternatively doped BiSb layer 410 having a (012) orientation over the buffer layer 406. Figure 8 The structure is other than the MRAM device to form the SOT MTJ 801.

[0092] The CoB layers described herein promote high resistivity, negative magnetostriction, and low coercivity at relatively low thickness, which promotes SOT performance and / or magnetic recording performance.

[0093] Fig. 9 is a diagram showing a graph of magnetostriction (in ppm) of the CoB layer (FL) 414 versus the thickness of the NL 412 material (in Angstroms).

[0094] Each curve 901 to 904 corresponds to a Co-containing material having a different Fe atomic percentage. For the first curve 901, the Fe atomic percentage is 60%. For the second curve 902, the Fe atomic percentage is 25%. For the third curve 903, the Fe atomic percentage is 10%. For the fourth curve 904, the Fe atomic percentage is 0%, making the material Co.

[0095] like Fig. 9 As shown, a thinner magnetic NL 412 (including a Heusler) may be used to reduce magnetostriction of the CoB layer 414 at a given thickness of the CoB layer 414 .

[0096] In one embodiment, a spin-orbit torque (SOT) device includes a seed layer and a capping layer spaced apart from the seed layer. The capping layer is nonmagnetic. The SOT device includes a spin-orbit torque (SOT) layer and a nanolayer (NL) between the seed layer and the capping layer. The NL is magnetic. The SOT device includes a cobalt-boron (CoB) layer between the seed layer and the capping layer, and the CoB layer is ferromagnetic. The CoB layer is substantially free of materials other than cobalt (Co) and boron (B). Most of the phases of the CoB layer are amorphous. The B atomic percentage of the CoB layer is in the range of 5% to 30%, and the Co atomic percentage of the CoB layer is in the range of 65% to 90%. The B atomic percentage and the Co atomic percentage add up to at least 95% of the total atomic percentage of the CoB layer. In one or more examples, the B atomic percentage is about 20%. The first thickness of the CoB layer is at least 40 angstroms. In one or more examples, the first thickness is in the range of 50 angstroms to 100 angstroms. The second thickness of the NL is 5 angstroms or less. The third thickness of the cover layer is 50 angstroms or less. The SOT device includes a first insertion layer between the CoB layer and the cover layer, and the first insertion layer is formed of hafnium (Hf). The SOT device includes a second insertion layer between the first insertion layer and the cover layer, and the second insertion layer is formed of tantalum (Ta). The thickness of each of the first insertion layer and the second insertion layer is in the range of 10 angstroms to 15 angstroms. A magnetic recording device having a SOT device is also disclosed.

[0097] In one embodiment, a spin-orbit torque (SOT) device includes a spin-orbit torque (SOT) layer including bismuth antimony (BiSb), and a cobalt-boron (CoB) layer. The CoB layer is ferromagnetic; the SOT device includes a nanolayer (NL) between the SOT layer and the CoB layer. The NL is magnetic. The SOT device includes one or more insertion layers, the one or more insertion layers are above the CoB layer, so that the CoB layer is between the NL and the one or more insertion layers. The NL is formed of a magnetic material, the magnetic material including one or more of cobalt (Co), nickel-iron (NiFe), cobalt-iron (CoFe), or Heusler alloy. In one or more examples, the magnetic material of the NL includes Co2FeGe. The resistivity of the CoB layer is at least 120 μOhms-cm. The SOT device includes a seed layer and a capping layer spaced apart from the seed layer. The capping layer is nonmagnetic. The SOT device includes a buffer layer between the seed layer and the SOT layer. Each of the SOT layer, the NL, the CoB layer, and the one or more insertion layers is between the buffer layer and the capping layer. The SOT device includes a first electrode and a second electrode spaced apart from the first electrode. Each of the seed layer, the cap layer, and the buffer layer is between the first electrode and the second electrode. A magnetic recording device having the SOT device is also disclosed.

[0098] In one embodiment, a spin-orbit torque (SOT) device includes a seed layer and a cover layer spaced apart from the seed layer. The cover layer is nonmagnetic. The SOT device includes a polarization device between the seed layer and the cover layer. The polarization device is magnetic. The SOT device includes a cobalt-boron (CoB) layer between the polarization device and the cover layer, and the CoB layer is ferromagnetic. The SOT device includes one or more insertion layers between the CoB layer and the cover layer.

[0099] The benefits of the present disclosure include lower negative magnetostriction, low coercivity, and high resistivity at relatively low thickness. The benefits of the present disclosure also include high spin Hall effect, enhanced recording performance (e.g., SOT performance), increased spin polarization, increased signal amplitude, high signal-to-noise ratio, and / or reduced magnetic signal shunting.

[0100] It is contemplated that one or more aspects disclosed herein may be combined. Furthermore, it is contemplated that one or more aspects disclosed herein may include some or all of the aforementioned benefits. As an example, one or more of the aspects, components, features, operations, and / or properties of the magnetic recording device 100, read / write head 200, read head 300, read head 350, read head 375, SOT device 400, SOT device 450, SOT device 500, SOT device 700, and / or MRAM device 800 may be combined.

[0101] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be envisaged without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the appended claims.

Claims

1. A spin-orbit torque (SOT) device, the SOT device comprising: Seed layer; a capping layer spaced apart from the seed layer, wherein the capping layer is nonmagnetic; Spin-Orbit Torque (SOT) Layer: a nanolayer (NL), the NL being between the seed layer and the capping layer, wherein the NL is magnetic; and A cobalt-boron (CoB) layer is between the seed layer and the capping layer, wherein the CoB layer is ferromagnetic and substantially free of materials other than cobalt (Co) and boron (B). 2 . The SOT device according to claim 1 , wherein a majority phase of the CoB layer is amorphous. 3 . The SOT device according to claim 1 , wherein the B atomic percentage of the CoB layer is in a range of 5% to 30%, and the Co atomic percentage of the CoB layer is in a range of 65% to 90%. 4 . The SOT device of claim 3 , wherein the B atomic percentage and the Co atomic percentage added together equal at least 95% of the total atomic percentage of the CoB layer. The SOT device of claim 3 , wherein the B atomic percentage is about 20%. The SOT device of claim 1 , wherein the first thickness of the CoB layer is at least 35 angstroms. The SOT device according to claim 6 , wherein the first thickness is in a range of 50 angstroms to 100 angstroms. The SOT device according to claim 6 , wherein the second thickness of the NL is 5 angstroms or less. 9 . The SOT device according to claim 8 , wherein the third thickness of the capping layer is 50 angstroms or less.

10. The SOT device according to claim 1, further comprising: a first insertion layer, the first insertion layer being between the CoB layer and the cover layer, the first insertion layer being formed of hafnium (Hf); and A second insertion layer is provided between the first insertion layer and the cover layer, and the second insertion layer is formed of tantalum (Ta). 11 . The SOT device of claim 10 , wherein each of the first insertion layer and the second insertion layer has a thickness in a range of 10 angstroms to 15 angstroms. 12 . A magnetic recording apparatus comprising the SOT device according to claim 1 .

13. A spin-orbit torque (SOT) device, the SOT device comprising: a spin-orbit torque (SOT) layer comprising bismuth antimony (BiSb); a cobalt-boron (CoB) layer, wherein the CoB layer is ferromagnetic; a nanolayer (NL), the NL being between the SOT layer and the CoB layer, wherein the NL is magnetic; and One or more insertion layers, the one or more insertion layers are above the CoB layer such that the CoB layer is between the NL and the one or more insertion layers. 14 . The SOT device of claim 13 , wherein the NL is formed of a magnetic material comprising one or more of cobalt (Co), nickel-iron (NiFe), cobalt-iron (CoFe), or Heusler alloy.

15. The SOT device of claim 14, wherein the magnetic material of the NL comprises Co2FeGe.

16. The SOT device of claim 13, wherein the CoB layer has a resistivity of at least 100 μOhms-cm.

17. The SOT device according to claim 13, further comprising: Seed layer; a capping layer spaced apart from the seed layer, wherein the capping layer is nonmagnetic; and a buffer layer, the buffer layer being between the seed layer and the SOT layer, Wherein each of the SOT layer, the NL, the CoB layer, and the one or more insertion layers is between the buffer layer and the cover layer.

18. The SOT device according to claim 17, further comprising: a first electrode; and a second electrode, the second electrode being spaced apart from the first electrode; wherein each of the seed layer, the capping layer, and the buffer layer is between the first electrode and the second electrode. 19 . A magnetic recording apparatus comprising the SOT device according to claim 13 .

20. A spin-orbit torque (SOT) device, the SOT device comprising: Seed layer; a capping layer spaced apart from the seed layer, wherein the capping layer is nonmagnetic; a polarizing device, the polarizing device being between the seed layer and the cover layer, wherein the polarizing device is magnetic; a cobalt-boron (CoB) layer, the CoB layer being between the polarization device and the cover layer, wherein the CoB layer is ferromagnetic; and One or more insertion layers, the one or more insertion layers are between the CoB layer and the cover layer.

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