Sot differential reader and method of manufacturing the same

Abstract

The present disclosure generally relates to spin orbit torque (SOT) differential reader designs. The SOT differential reader is a multi-terminal device that includes a first shield, a first spin hall effect layer, a first free layer, a gap layer, a second spin hall effect layer, a second free layer, and a second shield. The gap layer is disposed between the first spin hall effect layer and the second spin hall effect layer. Electrical lead connections are located around the first spin hall effect layer, the second spin hall effect layer, the gap layer, the first shield, and / or the second shield. The electrical lead connections facilitate current flow from a negative lead to a positive lead and / or voltage from the negative lead to the positive lead. The positioning of the electrical lead connections and the positioning of the SOT differential layers increase reader resolution without reducing shield-to-shield spacing (i.e., read gap).

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Application No. 16 / 918,841, filed July 1, 2020, the entire contents of which are incorporated herein by reference. Background Technology Technical Field

[0004] The implementation scheme disclosed herein generally relates to the read head of a data storage device.

[0005] Description of related fields

[0006] At the heart of a computer's functionality and capabilities lies the storage and writing of data to data storage devices (such as hard disk drives (HDDs)). The amount of data processed by computers is rapidly increasing. This necessitates higher recording densities in magnetic recording media to enhance computer functionality and capabilities.

[0007] To achieve higher recording densities (such as exceeding 2 terabits per inch) in magnetic recording media 2 The recording density (i.e., the width and spacing of the write tracks are narrowed, thus narrowing the corresponding magnetic recording bits encoded in each write track) has led to attempts to achieve higher recording density reads using advanced narrow-gap reader sensors that utilize magnetoresistive sensors with free layers composed of highly saturated magnetized materials to realize the read head.

[0008] A typical read head consists of a read sensor sandwiched between two shields. The shield-to-shield spacing between the two shields plays a crucial role in the read sensor's resolution. However, conventional read sensors have been minimized to approximately 25 nm and cannot be further reduced in size to decrease the shield-to-shield spacing.

[0009] Therefore, there is a need in this field for improved magnetic reading heads. Summary of the Invention

[0010] This disclosure generally relates to the design of a spin-orbit torque (SOT) differential reader. The SOT differential reader is a multi-terminal device comprising a first shield, a first spin Hall effect layer, a first free layer, a gap layer, a second spin Hall effect layer, a second free layer, and a second shield. The gap layer is disposed between the first spin Hall effect layer and the second spin Hall effect layer. Electrical lead connections are located around the first spin Hall effect layer, the second spin Hall effect layer, the gap layer, the first shield, and / or the second shield. These electrical lead connections facilitate the flow of current from the negative lead to the positive lead and / or the voltage from the negative lead to the positive lead. The positioning of these electrical lead connections and the positioning of these SOT differential layers improve the reader resolution without reducing the shield-to-shield spacing (i.e., the read gap).

[0011] In one embodiment, the magnetic recording head includes a first shield, a second shield, a first bias layer, a second bias layer, and a spin-orbit torque (SOT) differential reader disposed between the first and second shields and between the first and second bias layers. The SOT differential reader includes: a first free layer; a second free layer; a first spin Hall effect layer; a second spin Hall effect layer in contact with the first and second bias layers; and one or more insulating layers, wherein the first insulating layer is disposed between the first spin Hall effect layer and the first bias layer, and the second insulating layer is disposed between the first spin Hall effect layer and the second bias layer.

[0012] In another embodiment, the magnetic recording head includes a first shield, a second shield, and a SOT differential reader disposed on a surface facing the medium between the first and second shields. The SOT differential reader includes a first free layer, a second free layer, a gap layer, a first spin Hall effect layer, and a second spin Hall effect layer, wherein the positive terminal of the first spin Hall effect layer is electrically connected to the positive terminal of the second spin Hall effect layer, and the signal read from the SOT differential reader is based on the voltage difference across the negative terminal of the first spin Hall effect layer to the negative terminal of the second spin Hall effect layer.

[0013] In another embodiment, a method of forming an SOT differential reader includes: depositing a first spin Hall effect layer over a first shield; depositing a first free layer on the first spin Hall effect layer; depositing a gap layer on the first free layer; depositing a second free layer on the gap layer; depositing a second spin Hall effect layer on the second free layer; and depositing a first insulating layer on the second spin Hall effect layer to form a stack; removing a portion of the first spin Hall effect layer, a portion of the first free layer, a portion of the gap layer, a portion of the second free layer, a portion of the second spin Hall effect layer, and a portion of the first insulating layer to define the track width of the stack; depositing a second insulating layer that contacts a first surface, a second surface, and a third surface of the stack, wherein a fourth surface of the stack is a dielectric-facing surface; removing a portion of the second insulating layer that contacts the second spin Hall effect layer; depositing a first bias layer and a second bias layer on the first and second surfaces of the stack, the first bias layer and the second bias layer contacting the second spin Hall effect layer and the first insulating layer; and depositing a second shield over the stack.

[0014] In another embodiment, a method of forming a SOT differential reader includes: depositing a first free layer over a first shield, depositing a first spin Hall effect layer on the first free layer, and depositing a gap layer on the first spin Hall effect layer to form a first stack; removing a portion of the first free layer, a portion of the first spin Hall effect layer, and a portion of the gap layer to define a first track width of the first stack; depositing a first insulating layer that contacts a first surface, a second surface, and a third surface of the first stack, wherein a fourth surface of the first stack is disposed at a surface facing the dielectric; and removing the first insulating layer from the first spin Hall effect layer. The portion in contact with the gap layer; depositing a first bias layer in contact with the first spin Hall effect layer, the gap layer, and the first insulating layer; depositing a second spin Hall effect layer on the gap layer and a second free layer on the second spin Hall effect layer to form a second stack on the first stack; removing a portion of the second spin Hall effect layer and a portion of the second free layer to define a second track width of the second stack; depositing a second insulating layer in contact with the first, second, and third surfaces of the second stack, wherein a fourth surface of the second stack is disposed on the surface facing the dielectric; and depositing a second shielding element over the second stack. Attached Figure Description

[0015] Therefore, a detailed understanding of the foregoing features of this disclosure, a more specific description of this disclosure, and the foregoing brief overview can be obtained by referring to the embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the drawings only illustrate typical embodiments of this disclosure and should therefore not be considered as limiting its scope, as this disclosure allows for other equally effective embodiments.

[0016] Figure 1 A disk drive embodying this disclosure is shown.

[0017] Figure 2 This is a segmented cross-sectional side view of the center of the read / write head facing the magnetic medium, according to one embodiment.

[0018] Figures 3A to 3E An SOT differential reader according to one embodiment is shown.

[0019] Figures 4A to 4H The formation and definition according to one embodiment are shown. Figure 3C Methods for determining the track width of SOT differential readers.

[0020] Figures 5A to 5H The formation and definition according to one embodiment are shown. Figure 3D Methods for determining the track width of SOT differential readers.

[0021] Figures 6A to 6E The formation and definition according to one embodiment are shown. Figure 3E Method for determining the bar height of the SOT differential reader 380.

[0022] Figures 7A to 7B An SOT differential reader according to one embodiment is shown.

[0023] Figures 8A to 8L The formation and definition according to one embodiment are shown. Figure 7A Methods for determining the track width of SOT differential readers.

[0024] Figures 9A to 9L The formation and definition according to another embodiment are shown. Figure 7A Methods for determining the track width of SOT differential readers.

[0025] Figures 10A to 10H The formation and definition according to one embodiment are shown. Figure 7B Methods for determining the bar height of the SOT differential reader.

[0026] For ease of understanding, the same reference numerals are used where possible to denote the same elements common in the accompanying drawings. It is conceivable that elements disclosed in one embodiment may be advantageously used in other embodiments without specific description. Detailed Implementation

[0027] In the following text, reference is made to embodiments of this disclosure. However, it should be understood that this disclosure is not limited to the specifically described embodiments. Rather, consider any combination of the following features and elements (whether or not related to different embodiments) to achieve and practice this disclosure. Furthermore, while embodiments of this disclosure may achieve advantages over other possible solutions and / or over the prior art, achieving a particular advantage through a given embodiment is not a limitation of this disclosure. Therefore, the following aspects, features, embodiments, and advantages are illustrative only and should not be considered elements or limitations of the appended claims unless expressly stated in the claims. Similarly, reference to “this disclosure” should not be construed as a generalization of any inventive subject matter disclosed herein and should not be considered elements or limitations of the appended claims unless expressly stated in the claims.

[0028] This disclosure generally relates to the design of a spin-orbit torque (SOT) differential reader. The SOT differential reader is a multi-terminal device comprising a first shield, a first spin Hall effect layer, a first free layer, a gap layer, a second spin Hall effect layer, a second free layer, and a second shield. The gap layer is disposed between the first spin Hall effect layer and the second spin Hall effect layer. Electrical lead connections are located around the first spin Hall effect layer, the second spin Hall effect layer, the gap layer, the first shield, and / or the second shield. These electrical lead connections facilitate the flow of current from the negative lead to the positive lead and / or the voltage from the negative lead to the positive lead. The positioning of these electrical lead connections and the positioning of these SOT differential layers improve the reader resolution without reducing the shield-to-shield spacing (i.e., the read gap).

[0029] Figure 1 A disk drive 100 embodying the present disclosure is shown. As shown, at least one rotatable magnetic medium 112 is carried on a spindle 114 and rotated by a disk drive motor 118. Magnetic records on each disk are in the form of any suitable pattern of data tracks, such as a toroidal pattern of concentric data tracks (not shown) on the magnetic medium 112.

[0030] At least one slider 113 is positioned near a magnetic medium 112, and each slider 113 supports one or more head assemblies 121. As the magnetic medium rotates, the slider 113 moves radially in and out above the medium surface 122, allowing the head assembly 121 to access different tracks of the magnetic medium 112 for writing desired data. 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 medium surface 122. Each actuator arm 119 is attached to an actuator device 127. Figure 1The actuator component 127 shown may be a voice coil motor (VCM). The VCM includes a coil capable of moving within a fixed magnetic field, the direction and speed of which the coil moves are controlled by a motor current signal supplied by the control unit 129.

[0031] During operation of the disk drive 100, the rotation of the magnetic medium 112 creates an air bearing between the slider 113 and the medium surface 122, which applies an upward force or lift to the slider 113. Thus, during normal operation, the air bearing counteracts the slight spring force of the suspension 115 and supports the slider 113 away from and slightly above the surface of the medium 112 with a small, substantially constant gap. In the case of EAMR, the DC magnetic field generated from the auxiliary elements of the head assembly 121 enhances the write capability, allowing the write elements of the head assembly 121 to effectively magnetize data bits in the medium 112.

[0032] Various components of the disk drive 100 are controlled during operation by control signals (such as access control signals and internal clock signals) generated by the control unit 129. Typically, the control unit 129 includes logic control circuitry, storage 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 a desired current distribution to optimally move and position the slider 113 onto the desired data track on the medium 112. Write and read signals are transmitted via the recording channel 125 to and from the write and read heads on component 121.

[0033] The above description of a typical disk storage system and Figure 1 The accompanying description is for illustrative purposes only. It should be obvious that a disk storage system may contain a large number of disks and actuators, and each actuator may support multiple sliders.

[0034] Figure 2 This is a segmented cross-sectional side view of a read / write head 200 facing the center of a magnetic medium 112, according to one embodiment. The read / write head 200 may correspond to... Figure 1 The magnetic head assembly 121 is described herein. The read / write head 200 includes a media-facing surface (MFS) 212, such as an air bearing surface (ABS), a magnetic write head 210, and a magnetic read head 211, and is mounted such that the MFS 212 faces the magnetic medium 112. The read / write head 200 can be an energy-assisted magnetic recording (EAMR) head. Figure 2 In the process, 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.

[0035] In some embodiments, the magnetic read head 211 is a SOT differential reader 204 located between shields S1 and S2. In other embodiments, the magnetic read head 211 is a magnetoresistive (MR) read head, which includes an MR sensing element 204 located between MR shields S1 and S2. In some other embodiments, the magnetic read head 211 is a magnetic tunnel junction (MTJ) read head, which includes an MTJ sensing element 204 located between MR shields S1 and S2. The magnetic field of adjacent magnetized regions in the magnetic medium 112 can be detected as a recorded bit by the MR (or MTJ) sensing element 204.

[0036] The write head 210 includes a return pole 206, a main pole 220, a rear shield 240, and a coil 218 for activating the main pole 220. The coil 218 may have a "pancake" structure, rather than... Figure 2 The illustrated "spiral" structure, a "pancake" structure, is wound around the back contact between the master electrode 220 and the return electrode 206. A rear gap (not shown) and a front gap (not shown) may contact the master electrode, and a front shield (not shown) may contact the front gap. A recording magnetic field is generated from the master electrode 220, and the rear shield 240 helps to steepen the magnetic field gradient of the master electrode 220. The master electrode 220 may be a magnetic material, such as an FeCo alloy. The master electrode 220 may include a rear surface 222, which may be parallel to the front surface 236 of the rear shield 240. The master electrode 220 may be a tapered write electrode (TWP) with a trailing edge taper (TET) configuration. In one embodiment, the master electrode 220 has a saturation magnetization (Ms) of 2.4 T and a thickness of approximately 300 nanometers (nm). The master electrode 220 may include a ferromagnetic material, typically an alloy of one or more of Co, Fe, and Ni. The rear shield 240 may be a magnetic material, such as a NiFe alloy. In one embodiment, the rear shield 240 has Ms of about 1.2T to about 1.6T.

[0037] Figures 3A to 3E An SOT differential reader according to one embodiment is shown. Figures 3A to 3B Configurations of SOT differential readers 300A and 300B according to various embodiments are shown. The SOT differential reader 300 can be located in... Figure 2 SOT differential reader 204 between the two shields S1 and S2. Figure 3A and Figure 3B Each of these has: (1) a top stacked configuration view of the reader, and (2) a bottom abstract view showing the positioning of the free layer relative to the magnetic medium when the recording head is above the medium, where other layers in the stacked configuration are omitted. Figure 3A and Figure 3BAs shown in the top stacked configuration view, a first free layer (FL) 306 is deposited on first spin Hall effect (SHE) layers 302a and 302b (collectively referred to as first SHE layer 302), a gap layer (GL) 310 is deposited on the first FL 306, a second FL 308 is deposited on the GL 310, and second SHE layers 304a and 304b (collectively referred to as second SHE layer 304) are deposited on the second FL 308. In the description herein, for illustrative purposes, the multiple SHE layers may be referred to as multiple spin Hall layers (SHL). The SOT differential reader 300 may each have a bar height between about 100 angstroms and about 400 angstroms.

[0038] In the bottom view, the first FL 306 and the second FL 308 are shown rotated 90 degrees from the stacked configuration view above and positioned vertically above the magnetic medium 312, wherein the magnetic medium 312 may be Figure 1 The magnetic medium 312 has a first FL 306 and a second FL 308 parallel to the magnetic field direction of the magnetic medium 312. The magnetic medium 312 includes a first magnetic field direction (indicated by an upward-pointing first arrow in bits 314a and 314c) and a second magnetic field direction (indicated by a downward-pointing second arrow in bits 314b and 314d). The magnetic medium 312 also includes a first bit 314a having the first magnetic field direction, a second bit 314b having the second magnetic field direction, a third bit 314c having the first magnetic field direction, and a fourth bit 314d having the second magnetic field direction. Although four bits 314a-314d are shown, the magnetic medium may have any number of bits.

[0039] exist Figure 3A In the top stacked configuration view, the positive terminal 305b of the first SHL 302a is electrically connected to the positive terminal 305b of the second SHL 304a, and the negative terminal 305a of the first SHL 302a is electrically connected to the negative terminal 305a of the second SHL 304a. Referring to the bottom abstract view, when the first FL 306 and the second FL 308 are each positioned above a single position (such as the third position 314c) of the plurality of positions 314a-314d of the magnetic medium 312, the magnetic field of the third position 314c exerts a magnetic force on the first FL 306 and the second FL 308. Due to the magnetic force exerted on the first FL 306 and the second FL 308, the magnetic moments of the first FL 306 and the second FL 308 are both in the same direction as the magnetic field of the third position 314c.

[0040] exist Figure 3BIn the top stacked configuration view, the positive terminal 309b of the first SHL 302b is electrically connected to the negative terminal 307a of the second SHL 304b, and the negative terminal 309a of the first SHL 302b is electrically connected to the positive terminal 307b of the second SHL 304b. Referring to the bottom abstract view, when the first FL 306 and the second FL 308 are respectively positioned above adjacent positions (such as the second position 314b and the third position 314c) of the plurality of positions 314a-314d of the magnetic medium 312, the magnetic field of the second position 314b applies a magnetic force to the first FL 306, and the third position 314c applies a magnetic force to the second FL 308, which is opposite to the magnetic force applied to the first FL 306. Due to the magnetic force applied to the first FL 306 and the second FL 308, the magnetic moment of the first FL 306 is in the same direction as the magnetic field of the second FL 314b, and the magnetic moment of the second FL 308 is in the same direction as the magnetic field of the third FL 314c. Figure 3B In this context, because the first FL 306 and the second FL 308 are located above adjacent positions among the multiple positions 314a-314d of the magnetic medium 312, the first FL 306 has a magnetic field direction opposite to that of the second FL 308.

[0041] exist Figure 3A and Figure 3B In this embodiment, the first SHL 302 and the second SHL 304 each comprise the same material and have the same thickness in the y-direction. The first SHL 302 and the second SHL 304 may be formed of a non-magnetic heavy metal material selected from the group consisting of Ta, Pt, W, Hf, Bi, and alloys thereof. Furthermore, it should be understood that while Ta, Pt, W, Hf, Bi, and alloys thereof have been exemplified as materials for the first SHL 302 and the second SHL 304, other materials are contemplated, and the embodiments discussed herein are not limited. For example, BiSb and BiSe may be used as materials for the first SHL 302 and the second SHL 304. The first SHL 302 and the second SHL 304 may have a wider width than the first FL layer 306 and the second FL layer 308, as well as GL 310. In one embodiment, the first SHL 302 and the second SHL 304 have the same width. In another embodiment, the first SHL 302 and the second SHL 304 have different widths.

[0042] exist Figure 3AIn this process, the first SHL 302a and the second SHL 304a each generate a transverse voltage signal (i.e., a SHE signal) within their respective first SHL 302a and second SHL 304a. The generated transverse voltage signal may be due to the spin Hall effect. The direction of the transverse voltage signal may depend on the electron flow direction and magnetic orientation of the first FL 306 and the second FL 308. For example, in Figure 3A In the bottom view, the first FL 306 and the second FL 308 are each vertically positioned above the same position (such as the third position 314c). The first SHL 302a and the second SHL 304a have the same SHE voltage polarity, with the side in the -x direction being the negative terminal 305a and the side in the +x direction being the positive terminal 305b.

[0043] Furthermore, the negative terminals 305a of the first SHL 302a and the second SHL 304a are connected, such that the negative terminals 305a of the first SHL 302a and the second SHL 304a share an equal voltage potential. The reader signal output can be determined by the voltage difference or differential voltage 311 between the positive terminals 305b of the first SHL 302a and the second SHL 304a. Because the first SHL 302a and the second SHL 304a each comprise the same material and the same current flow direction, the SHE voltage induced by the first SHL 302a can be equal in both polarity and magnitude to the SHE voltage induced by the second SHL 304a. The differential voltage 311 between the two positive terminals 305b can be canceled or reduced. The differential voltage 311 can be a net differential output or approximately zero. Current 313 travels from the first SHL 302a to GL 310. Current 313 travels from GL 310 to the second SHL 304a. Therefore, the SOT differential reader 300A is a multi-terminal device. Because the first SHL 302a and the second SHL 304a have the same voltage polarity, the signal output is greatly reduced.

[0044] exist Figure 3BIn the bottom view, the first FL 306 and the second FL 308 are positioned above adjacent positions, for example, the first FL 306 is vertically positioned above the second position 314b and the second FL is vertically positioned above the third position 314c. The first FL 306 and the second FL 308 have different and opposite magnetizations. For example, the first SHL 302b has a first SHE voltage, where the side in the -x direction is the positive terminal 309b and the side in the +x direction is the negative terminal 309a. Similarly, the second SHL 304b has a second SHE voltage, where the side in the -x direction is the negative terminal 307a and the side in the +x direction is the positive terminal 307b. Furthermore, the positive terminal 309b of the first SHL 302b and the negative terminal 307a of the second SHL 304b are connected and share an equal voltage potential. The differential voltage 311 is determined by the difference between the voltage at the positive terminal 307b of the second SHL 304b and the voltage at the negative terminal 309a of the first SHL 302b. Because the induced voltages of the first SHL 302b and the second SHL 304b are in opposite directions, the differential voltage 311 effectively doubles the output signal. Current 313 travels from the first SHL 302b to GL 310. Then, current 313 travels from GL 310 to the second SHL 304b. Therefore, the SOT differential reader 300B is a multi-terminal device. Because the first SHL 302b and the second SHL 304b have opposite voltage directions, the signal output can be effectively doubled or greatly increased.

[0045] Figure 3C An MFS view of an SOT differential reader 360 according to one embodiment is shown. The SOT differential reader 360 can be... Figure 3A SOT differential reader 300A and / or Figure 3B The SOT differential reader 300B. In addition, the first SHL 302a, 302b can be the first SHL 302, and the second SHL 304a, 304b can be the second SHL 304.

[0046] The SOT differential reader 360 also includes a first shield 322a deposited beneath the first insulating layer 330, wherein a first SHL 302 is deposited on the first insulating layer 330. Furthermore, a second insulating layer 332a and a third insulating layer 332b are deposited to contact the respective surfaces of the first SHL 302, the first FL 306, the GL 310, and the second FL 308. A first hard bias layer 324a is deposited to contact the second insulating layer 332a and the second SHL 304. A second hard bias layer 324b is deposited to contact the third insulating layer 332b and the second SHL 304. The second insulating layer 332a and the third insulating layer 332b prevent the first SHL 302, the first FL 306, the GL 310, and the second FL 308 from directly contacting the first hard bias layer 324a and the second hard bias layer 324b. Furthermore, a fourth insulating layer 320 is deposited on the second SHL 304, the first hard bias layer 324a, and the second hard bias layer 324b. A second shield 322b is deposited on the fourth insulating layer 320. The first SHL 302 has a larger width or length in the x-direction than the second SHL 304 (i.e., a larger track width in the cross-track direction).

[0047] Insulating layers 330, 332a, 332b, and 320 are placed within the SOT differential reader 360 to prevent electrical short circuits between the first shield 322a, the first SHL 302, the first FL 306, GL 310, the second FL 308, the second SHL 304, the second shield 322, the first hard bias layer 324a, and the second hard bias layer 324b. Suitable materials for insulating layers 330, 332a, 332b, and 320 include dielectric materials such as aluminum oxide, silicon oxide, magnesium oxide, and silicon nitride. Insulating layers 330, 332a, 332b, and 320 can be formed by well-known deposition methods, such as atomic layer deposition (ALD), physical vapor deposition (PVD), ion beam deposition (IBD), or sputtering. The insulating layers 330, 332a, 332b, and 320 may have a thickness between about 10 angstroms and about 100 angstroms.

[0048] The first FL 306 and the second FL 308 comprise the same material and have the same thickness in the y-direction. The first FL 306 and the second FL 308 have a greater thickness in the y-direction than the first SHL 302 and the second SHL 304. In some embodiments, the first FL 306 and the second FL 308 each comprise a CoFe / CoFeB / Ta / NiFe multilayer stack. The CoFe layer may have a thickness between about 3 angstroms and about 10 angstroms. The CoFeB layer may have a thickness between about 10 angstroms and about 20 angstroms. The Ta layer may have a thickness between about 0.5 angstroms and about 2 angstroms. The NiFe layer may have a thickness between about 3 angstroms and about 100 angstroms, such as between about 3 angstroms and about 10 angstroms or between about 10 angstroms and about 100 angstroms. The first FL 306 and the second FL 308 may be formed by a well-known deposition method, such as sputtering. Furthermore, it should be understood that while CoFe / CoFeB / Ta / NiFe has been exemplified as the material for the first FL 306 and the second FL 308, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe / CoFeB / Ta / NiFe used in the first FL 306 and the second FL 308. Additionally, the previously mentioned dimensions are not intended to be limiting, but rather to provide examples of possible embodiments.

[0049] GL 310 has a smaller thickness in the y-direction than the first SHL 302 and the second SHL 304. GL 310 may be formed of a non-magnetic conductive material (such as Cr) with a thickness between about 10 angstroms and about 50 angstroms. In some embodiments, GL 310 may have a thickness between about 0 angstroms and about 20 angstroms. It should be understood that while Cr is exemplified as GL 310, other materials are contemplated, and the embodiments discussed herein are not limited to Cr used for GL 310. In some embodiments, an insulating material may be used for the GL 310 material, such as when GL 310 has a thickness of less than about 1 nm.

[0050] The first shield 322a and the second shield 322b each comprise a conductive material selected from the group consisting of Cu, W, Ta, Al, NiFe, CoFe, and alloys thereof. The shielding material may include NiFe alloys, CoFe alloys, or combinations of NiFe alloys or CoFe alloys with Cu, W, Ta, and Al. The thickness of each of the first shield 322a and the second shield 322b may be between about 20 nm and about 500 nm. Furthermore, it should be understood that while NiFe, CoFe, Cu, W, Ta, Al, and alloys thereof have been exemplified as materials for the first shield 322a and the second shield 322b, other materials are contemplated, and the embodiments discussed herein are not limited to NiFe, CoFe, Cu, W, Ta, Al, or alloys thereof used for the first shield 322a and the second shield 322b.

[0051] The first hard bias layer 324a and the second hard bias layer 324b may comprise a multilayer structure including a seed layer and a host layer. In one embodiment, the hard bias layer includes a Ta seed layer, a Cr or W seed layer disposed on the Ta seed layer, and a CoPt host layer disposed on the Cr or W seed layer. In some embodiments, the hard bias layer comprises multiple layers of the aforementioned materials. Furthermore, it should be understood that while Ta, Cr, W, and CoPt have been exemplified as materials for the first hard bias layer 324a and the second hard bias layer 324b, other materials are contemplated, and the embodiments discussed herein are not limited to Cu, Ta, W, Cr, and CoPt for the first hard bias layer 324a and the second hard bias layer 324b.

[0052] Electrical leads are positioned around the first SHL 302 and the second SHL 304. For example, the first SHL 302 includes a first negative voltage terminal (V1-), a first positive voltage terminal (V1+), and a first positive current terminal (I1+). Similarly, the second SHL 304 includes a first negative current terminal (I2-), a second positive voltage terminal (V2+), and a second negative voltage terminal (V2-). It should be understood that the indicated polarities of the voltage terminals of the first SHL 302 and the second SHL 304 are for illustrative purposes, and the voltage polarities of the first SHL 302 and the second SHL 304 may depend on the positioning of the first FL 306 and the second FL 308 relative to positions (such as positions 314a-314d) of the magnetic medium 312. Furthermore, the first negative voltage terminal (e.g., V1-) and the second negative voltage terminal (e.g., V2-) may be electrically short-circuited together to provide a common voltage terminal. The differential voltage (e.g., differential voltage 311) between the first positive voltage terminal of the first SHL 302 and the second positive voltage terminal of the second SHL 304 is the SOT differential reader signal output.

[0053] Figure 3D An MFS view of an SOT differential reader 370 according to another embodiment is shown. The SOT differential reader 370 can be... Figure 3A SOT differential reader 300A and / or Figure 3B The SOT differential reader 300B. Furthermore, the first SHLs 302a and 302b can be the first SHL 302, and the second SHLs 304a and 304b can be the second SHL 304. The aspects of the SOT differential reader 370 are similar to... Figure 3C The SOT differential reader 360, and Figures 3C to 3D The reference numerals for the components are consistent to reflect this.

[0054] The SOT differential reader 370 also includes an antiferromagnetic (AFM) / capping layer 326 deposited between a first soft bias layer 324c, a second soft bias layer 324d, and a fourth insulating layer 320. The AFM / capping layer 326 includes a material selected from a group of AFM materials, including IrMn, FeMn, PtMn, and other nonmagnetic conductive layers. Furthermore, the AFM / capping layer 326 may include a group of AFM materials and one or more materials from the group consisting of Ta, Ru, or Ti, other nonmagnetic materials, and / or multilayers thereof. The AFM / capping layer 326 may be formed by a well-known deposition method, such as sputtering. The AFM / capping layer 326 may have a thickness between about 40 angstroms and about 150 angstroms. Furthermore, it should be understood that while IrMn, FeMn, PtMn, Ta, Ru, Ti and their multilayers have been exemplified as AFM / capping layer 326 materials, other materials are also contemplated, and the embodiments discussed herein are not limited to IrMn, FeMn, PtMn, Ta, Ru or Ti or their multilayers for use in AFM / capping layer 326.

[0055] The first SHL 302 has a first track width 318 that is substantially equal to or less than the width of the first shield 322a, and the second SHL 304 has a second track width 328 that is substantially equal to the width of the stack including the first FL 306, GL 310, and the second FL 308. In some embodiments, the width of the first track width 318 is less than the width of the first shield 322a. The first track width 318 may be from about 200 angstroms to about 2000 angstroms wide. The second track width 328 may be from about 100 angstroms to about 400 angstroms wide.

[0056] Electrical leads are placed around the first SHL 302 and the second SHL 304. For example, the first SHL 302 includes a first negative voltage (V1-) terminal, a first positive voltage terminal (V1+), and a first negative current terminal (I1-). Similarly, the second SHL 304 includes a first negative current terminal (I2-), a second positive voltage terminal (V2+), and a second negative voltage terminal (V2-). It should be understood that the indicated polarities of the voltage terminals of the first SHL 302 and the second SHL 304 are for illustrative purposes, and the voltage polarities of the first SHL 302 and the second SHL 304 may depend on the positioning of the first FL 306 and the second FL 308 relative to positions (such as positions 314a-314d) of the magnetic medium 312. Furthermore, the first negative voltage terminal (V1-) and the second negative voltage terminal (V2-) may be electrically short-circuited together to provide a common voltage terminal. The differential voltage (e.g., differential voltage 311) between the first positive voltage terminal of the first SHL 302 and the second positive voltage terminal of the second SHL 304 is the SOT differential reader signal output.

[0057] In some implementations, the first positive voltage terminal (V1+) and the second negative voltage terminal (V2-) may be electrically connected to provide a common voltage terminal. The differential voltage (e.g., differential voltage 311) between the first negative voltage terminal of the first SHL 302 and the second positive voltage terminal of the second SHL 304 is the SOT differential reader signal output.

[0058] The first soft bias layer 324c and the second soft bias layer 324d may comprise a multilayer structure comprising a soft magnetic material. In one embodiment, the soft bias layer comprises a material selected from the group consisting of NiFe, CoFe, CoNi, CoFeNi, CoFeB, Co, alloys thereof, and / or multilayers thereof. Furthermore, it should be understood that while NiFe, CoFe, CoNi, CoFeNi, CoFeB, Co, alloys thereof, and / or multilayers thereof have been exemplified as materials for the first soft bias layer 324c and the second soft bias layer 324d, other materials are contemplated, and the embodiments discussed herein are not limited to NiFe, CoFe, CoNi, CoFeNi, CoFeB, Co, alloys thereof, and / or multilayers thereof used for the first soft bias layer 324c and the second soft bias layer 324d.

[0059] Figure 3E A cross-sectional side view of an SOT differential reader 380 according to one embodiment is shown, illustrating the bar height of the SOT differential reader's layers. The SOT differential reader 380 can be... Figure 3C SOT differential reader 360 or Figure 3D The SOT differential reader 370. Therefore, the material of the layer forming the SOT differential reader 380 is similar to... Figure 3C The material of the SOT differential reader 360 or Figure 3D The SOT differential reader 370 is made of the same material. The SOT differential reader 380 includes a first insulating layer 330 deposited on a first shield 322a, a first SHL 302 deposited on the first insulating layer 330, a first FL 306 deposited on the first SHL 302, a GL 310 deposited on the first FL 306, a second FL 308 deposited on the GL 310, and a second SHL 304 deposited on the second FL 308. A fourth insulating layer 320 is deposited on the first shield 322a and the second SHL 304, and on the respective back surfaces of the first insulating layer 330, the first SHL 302, the first FL 306, the GL 310, the second FL 308, and the second SHL 304. A second shield 322b is deposited on the fourth insulating layer 320.

[0060] Figures 4A to 4H The formation and definition according to one embodiment are shown. Figure 3C The method for determining the track width of the SOT differential reader 360. Although in Figures 4A to 4H Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 360 is the same as described above. Figure 3C The materials described are the same. Figures 4A to 4H The MFS view is shown during the manufacturing process of the SOT differential reader 360. Figure 4A In the first insulating layer 430, a first SHL 402 is deposited on the first insulating layer 430, a first FL 406 is deposited on the first SHL 402, a GL 410 is deposited on the first FL 406, a second FL 408 is deposited on the GL 410, a second SHL 404 is deposited on the second FL 408, and a second insulating layer 420a is deposited on the second SHL 404 to form a stack 440.

[0061] exist Figure 4B In this process, a photoresist or photo-stencil 434 is deposited on a second insulating layer 420a above the stack 440 to define the track width of the stack 440. Then, portions of the second insulating layer 420a, the second SHL 404, the second FL 408, the GL 410, and the first FL 406 that are not covered by the photo-stencil 434 (i.e., the outer ends of the stack 440) are removed to expose refill layers 436a and 436b disposed behind the stack 440. Removing the outer ends of the stack 440 defines the track width or horizontal width of the stack 440. Figure 4CIn this process, a thin layer of insulating material 432 is deposited on the top surface 402a of the first SHL 402, and on any side of the first FL 406, GL 410, the second FL 408, the second SHL 404, the second insulating layer 420a, and the photoelectric template 434 (e.g., the side in contact with the refill layers 436a, 436b).

[0062] exist Figure 4D In this process, hard bias layers 424a and 424b are deposited above the first SHL 402 (e.g., on the insulating material 432) and on both sides of the first FL 406, GL 410, and the second FL 408. Then, portions of the insulating material 432 and the refill layers 436a and 436b configured to contact the second SHL 404, the second insulating layer 420a, and the photoelectric template 434 are removed (e.g., by ion milling). Therefore, the third insulating layer 432a and the fourth insulating layer 432b remain in contact with the first SHL 402, the first FL 406, GL 410, and the second FL 408, such that the third insulating layer 432a and the fourth insulating layer 432b are disposed between the first SHL 402, the first FL 406, GL 410, and the second FL 408 and the hard bias layers 424a and 424b. In other words, the first SHL 402, the first FL 406, GL 410, and the second FL 408 are not in direct contact with the hard bias layers 424a and 424b. The first hard bias material 424a is deposited on the third insulating layer 432a at a level below the second SHL 404, and the second hard bias material is deposited on the fourth insulating layer 432b at a level below the second SHL 404. In one embodiment, the level is flush with the bottom edge of the second SHL 404.

[0063] exist Figure 4E In this process, an additional hard bias material 424c is deposited around and in contact with the second SHL 404, the second insulating layer 420a, and the optoelectronic template 434. The additional hard bias material 424c and the hard bias layers 424a and 424b form an adhesive hard bias layer, and are collectively referred to as hard bias layer 424 or hard bias material 424. Figure 4F In this process, a portion of the photoelectric template 434 and the hard bias layer 424 that are in contact with the photoelectric template 434 are removed by a process such as CMP-assisted stripping and shut-off.

[0064] exist Figure 4G In this process, the track width and strip height of the SOT differential reader 360 are defined through the steps discussed earlier, and then a fourth insulating layer 420b is deposited on and in contact with the second insulating layer 420a and the hard bias layer 424. Figure 4HIn this embodiment, the second shield 422b is deposited on and in contact with the fourth insulating layer 420b. In one embodiment, the first shield 422a and the second shield 422b comprise the same or similar materials. In another embodiment, the first shield 422a and the second shield 422b comprise different materials.

[0065] Figures 5A to 5H The formation and definition according to one embodiment are shown. Figure 3D Method for determining track width of SOT differential reader 370. Figures 5A to 5H An MFS view is shown during the manufacturing process of the SOT differential reader 370. Although in Figures 5A to 5H Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 370 is the same as described above. Figure 3D The materials described herein are the same. Figure 5A In the first insulating layer 530, a first SHL 502 is deposited on the first insulating layer 530, a first FL 506 is deposited on the first SHL 502, a GL 510 is deposited on the first FL 506, a second FL 508 is deposited on the GL 510, a second SHL 504 is deposited on the second FL 508, and a second insulating layer 520a is deposited on the second SHL 504 to form a stack 540.

[0066] exist Figure 5B In this process, a photoresist or photo-stencil 534 is deposited on a second insulating layer 520a above the stack 540 to define the track width of the stack 540. Then, portions of the second insulating layer 520a, the second SHL 504, the second FL 508, the GL 510, and the first FL 506 that are not covered by the photo-stencil 534 (i.e., the outer ends of the stack 540) are removed to expose refill layers 536a and 536b disposed behind the stack 540. Removing the outer ends of the stack 540 defines the track width or horizontal width of the stack 540. Figure 5C In this process, a thin layer of insulating material 532 is deposited on the top surface 502a of the first SHL 502, and on any side of the first FL 506, GL 510, the second FL 508, the second SHL 504, the second insulating layer 520a, and the photoelectric template 534.

[0067] exist Figure 5DIn this configuration, side shielding layers 524c and 524d are deposited above the first SHL 502 (e.g., on insulating material 532) and on both sides of the first FL 506, GL 510, and second FL 508. Side shielding layers 524c and 524d may include a soft bias material. Then, portions of insulating material 532 and refill layers 536a and 536b configured to contact the second SHL 504, the second insulating layer 520a, and the opto-template 534 are removed (e.g., by milling). Therefore, the third insulating layer 532a and the fourth insulating layer 532b remain in contact with the first SHL 502, the first FL 506, GL 510, and the second FL 508, such that the third insulating layer 532a and the fourth insulating layer 532b are disposed between the first SHL 502, the first FL 506, GL 510, and the second FL 508 and the side shielding layers 524c and 524d. In other words, the first SHL 502, the first FL 506, GL 510 and the second FL 508 do not directly contact the side shielding layers 524c and 524d.

[0068] exist Figure 5E In this process, an AFM / capping layer 536 is deposited on and in contact with the side shielding layers 524c and 524d, as well as the second SHL 504, the second insulating layer 520a, and the optoelectronic template 534. The AFM / capping layer 536 comprises a material selected from a group of AFM materials, including IrMn, FeMn, PtMn, and other non-magnetic conductive layers. Furthermore, the AFM / capping layer 536 may include a group of AFM materials and one or more materials from the group consisting of Ta, Ru, or Ti, other non-magnetic materials, conductive materials, and multilayers thereof. The AFM / capping layer 536 can be formed by a well-known deposition method, such as sputtering. The AFM / capping layer 536 may have a thickness between about 40 angstroms and about 150 angstroms. Furthermore, it should be understood that while IrMn, FeMn, PtMn, Ta, Ru, Ti, and their multilayers have been exemplified as AFM / capping layer 536 materials, other materials are contemplated, and the embodiments discussed herein are not limited to IrMn, FeMn, PtMn, Ta, Ru, or Ti, or their multilayers, for use in AFM / capping layer 536. Figure 5F In this process, a portion of the photoelectric template 534 and the AFM / capping layer 536 that is in contact with the photoelectric template 534 is removed using a process such as CMP-assisted stripping.

[0069] exist Figure 5G In this process, the track width and strip height of the SOT differential reader 370 are defined through the steps discussed earlier, and then a fourth insulating layer 520b is deposited on and in contact with the second insulating layer 520a and the AFM / capping layer 536. Figure 5HIn this configuration, the second shielding element 522b is deposited on and in contact with the fourth insulating layer 520b. In one embodiment, the first shielding element 522a and the second shielding element 522b comprise the same or similar materials. In another embodiment, the first shielding element 522a and the second shielding element 522b comprise different materials.

[0070] Figures 6A to 6E The formation and definition according to one embodiment are shown. Figure 3E Method for determining the bar height of the SOT differential reader 380. Figures 6A to 6E A cross-sectional side view of the SOT differential reader 380 is shown. Although in Figures 6A to 6E Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 380 is the same as described above. Figure 3E The materials described herein are the same. Figure 6A In the first insulating layer 630, a first SHL 602 is deposited on the first insulating layer 630, a first FL 606 is deposited on the first SHL 602, a GL 610 is deposited on the first FL 606, a second FL 608 is deposited on the GL 610, a second SHL 604 is deposited on the second FL 608, and a second insulating layer 620a is deposited on the second SHL 604 to form a stack 640.

[0071] exist Figure 6B In this process, a first photoresist or photo-stencil 634a is deposited on a second insulating layer 620a above a stack 640 to define the strip height of the stack 640 (i.e., in the z-direction). Then, portions of the second insulating layer 620a, the second SHL 604, the second FL 608, the GL 610, and the first FL 606 that are not covered by the photo-stencil 634a (i.e., the recessed rear end of the stack 640 from the MFS 650) are removed to expose the first insulating layer 630 disposed on the first shield 622a. Figure 6C In the process, the first optoelectronic template 634a is removed, and a third insulating layer 620b is deposited on the back surface 640a of the stack 640 (i.e., the surface 640a of the stack 640 recessed from the MFS 650) on the first insulating layer 630. The third insulating layer 620b is deposited onto the removed portion of the stack 640 recessed from the MFS 650. The third insulating layer 620b contacts the first SHL 602, the first FL 606, the GL 610, the second FL 608, the second SHL 604, and the second insulating layer 620a. The stack 640 then forms electrical leads for the SOT differential reader 380.

[0072] After depositing the third insulating layer 620b, the track width of the stack 640 can then be defined, as described above. Figures 4B to 4H and Figures 5B to 5H As described in [the text]. Once the track width of the stack 640 is defined, the second photoelectric template 634b is deposited on the second insulating layer 620a and the third insulating layer 620b, as [the text continues with details about the deposition process]. Figure 6D As shown, the electrical contacts are exposed. Then, a portion of the stack 640 and / or the third insulating layer 620b is etched (e.g., by wet etching with alumina) to open one or more electrical lead connections. Figure 6E In this configuration, the second shielding element 622a is deposited on and in contact with the second insulating layer 620a and the third insulating layer 620b. In one embodiment, the first shielding element 622a and the second shielding element 622b comprise the same or similar materials. In another embodiment, the first shielding element 622a and the second shielding element 622b comprise different materials.

[0073] Figures 7A to 7B A SOT differential reader 700 according to one embodiment is shown. A first FL 706 is deposited on a first shield 722a, a first SHL 702 is deposited on the first FL 706, a GL 710 is deposited on the first SHL 702, a second SHL 704 is deposited on the GL 710, and a second FL 708 is deposited on the second FL 708.

[0074] exist Figure 7A In this configuration, a first insulating layer 732a is located on a first side of the first FL 706, adjacent to a first bias layer 724c, and a second insulating layer 732b is located on a second side of the first FL 706, adjacent to a second bias layer 724d, wherein the second side is opposite to the first side. A third insulating layer 732c is located on a first side of the second FL 708, adjacent to the first bias layer 724c, and a fourth insulating layer 734c is located on a second side of the second FL 708, adjacent to the second bias layer 724d. Furthermore, the first bias layer 724c is deposited above the first shield 722a and is in contact with the first insulating layer 732a, the first SHL 702, GL 710, the second SHL 704, and the third insulating layer 732c. The second bias layer 724d is deposited above the first shield 722a and is in contact with the second insulating layer 732b, the first SHL 702, GL 710, the second SHL 704, and the fourth insulating layer 732d. In one embodiment, the first bias layer 724c and the second bias layer 724d are soft bias layers.

[0075] exist Figure 7A and Figure 7BIn this configuration, the AFM / capping layer 726 is deposited on the first bias layer 724c and the second bias layer 724d. A fifth insulating layer 720 is deposited on the second FL 708 and the AFM / capping layer 726. In one embodiment, a third insulating layer 732c and a fourth insulating layer 732d are located between the AFM / capping layer 726 and the fifth insulating layer 720. A second shield 722b is deposited on the fifth insulating layer 720. In some embodiments, the SOT differential reader 700 may not include the AFM / capping layer 726, and the first bias layer 724c and the second bias layer 724d are hard bias layers.

[0076] Insulating layers 732a-732d, 720 are placed within the SOT differential reader 700 to prevent electrical short circuits between the first shield 722a, the first SHL 702, the first FL 706, GL 710, the second FL 708, the second SHL 704, the AFM / capping layer 726, the second shield 722, the first bias layer 724c, and the second bias layer 724d. Suitable materials for insulating layers 732a-732d, 720 include dielectric materials such as alumina, silicon oxide, magnesium oxide, and silicon nitride. Insulating layers 732a-732d, 720 can be formed by well-known deposition methods, such as atomic layer deposition (ALD), physical vapor deposition (PVD), ion beam deposition (IBD), or sputtering. Insulating layers 732a-732d, 720 can have a thickness between about 10 angstroms and about 100 angstroms.

[0077] First FL 706 and second FL 708 comprise the same material and have the same thickness in the y-direction. First FL 706 and second FL 708 have a greater thickness in the y-direction than first SHL 702 and second SHL 704. First FL 706 and second FL 708 each comprise a CoFe / CoFeB / Ta / NiFe multilayer stack. The CoFe layer may have a thickness between about 3 angstroms and about 10 angstroms. The CoFeB layer may have a thickness between about 10 angstroms and about 20 angstroms. The Ta layer may have a thickness between about 0.5 angstroms and about 2 angstroms. The NiFe layer may have a thickness between about 3 angstroms and about 100 angstroms, such as between about 3 angstroms and about 10 angstroms or between about 10 angstroms and about 100 angstroms. First FL 706 and second FL 708 may be formed by a well-known deposition method, such as sputtering. Furthermore, it should be understood that while CoFe / CoFeB / Ta / NiFe has been exemplified as the material for the first FL 706 and the second FL 708, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe / CoFeB / Ta / NiFe used in the first FL 706 and the second FL 708. Additionally, the previously mentioned dimensions are not intended to be limiting, but rather to provide examples of possible embodiments.

[0078] GL 710 has a smaller thickness in the y-direction than the first SHL 702 and the second SHL 704. GL 710 may be formed of materials such as MgO or Cr, with a thickness between about 0 angstroms and about 20 angstroms. It should be understood that while MgO and Cr are exemplified as GL 710, other insulating materials are contemplated, and the embodiments discussed herein are not limited to MgO and Cr for use in GL 710. In some embodiments, the SOT differential reader 700 does not include GL 710, or GL 710 has a thickness of about zero angstroms.

[0079] The first shield 722a and the second shield 722b each comprise a conductive material selected from the group consisting of Cu, W, Ta, Al, NiFe, CoFe, and alloys thereof. The shielding material may include NiFe alloys, CoFe alloys, or combinations of NiFe alloys or CoFe alloys with Cu, W, Ta, Al, NiFe, or CoFe. The thickness of each of the first shield 722a and the second shield 722b may be between about 20 nm and about 500 nm. Furthermore, it should be understood that while Cu, W, Ta, Al, NiFe, CoFe, and alloys thereof have been exemplified as materials for the first shield 722a and the second shield 722b, other materials are contemplated, and the embodiments discussed herein are not limited to Cu, W, Ta, Al, NiFe, CoFe, and alloys thereof used for the first shield 722a and the second shield 722b.

[0080] Electrical leads are placed around a first shield 722a, a second shield 722b, a first bias layer 724c, and a second bias layer 724d. For example, the first shield 722a includes a first positive current terminal (I1+), and the second shield 722b includes a second positive current terminal (I2+). When current (I-) is introduced at GL 710 from either the first bias layer 724c or the second bias layer 724d (e.g., the negative current terminal shown in the second bias layer 724d), the current is shunted and flows to the first and second positive current terminals. The signal output of the SOT differential reader 700 is the voltage difference between the negative voltage terminal (V-) and the positive voltage terminal (V+) of the first SHL 702. Because the current flows in opposite directions in the first FL 706 and the second FL 708, the induced SHE spin Hall voltages along the first SHL 702 and the second SHL 704 will have the same polarity or opposite polarity, depending on the magnetization of the first FL 706 and the second FL 708.

[0081] The differential signal output across the negative and positive voltage terminals of either the first SHL 702 or the second SHL 704 depends on the positioning of the first FL 706 and the second FL 708 relative to the positions (such as positions 314a-314d) of the magnetic medium 312 in FIG3. For example, if the first FL 706 and the second FL 708 are vertically positioned above a single position, the differential signal output is canceled out or approximately zero. However, if the first FL 706 is vertically positioned above the first position with opposite magnetic orientation, and the second FL 708 is vertically positioned above a second position adjacent to the first position, the differential signal output is summed or can be effectively doubled.

[0082] Figures 8A to 8L The formation and definition according to one embodiment are shown. Figure 7A Method for determining track width of SOT differential reader 700. Figures 8A to 8L An MFS view is shown during the manufacturing process of the SOT differential reader 700. Although in Figures 8A to 8L Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 700 is the same as described above. Figure 3D and Figure 7A The materials described herein are the same. Figure 8A In the first SHL 802, a first FL 806 is deposited on the first SHL 802, and a GL 810 is deposited on the first FL 806 to form the first portion 840a of the stack 840.

[0083] exist Figure 8BIn this process, a first photoresist or photo-stencil 834a is deposited on GL 810 above the first stack portion 840a to define the track width of the first stack portion 840a. Then, the portions of GL 810, the first SHL 802, and the first FL 806 that are not covered by the first photo-stencil 834a (i.e., the outer ends of the first stack portion 840a) are removed to expose the refill layers 836a and 836b disposed behind the first stack portion 840a. Removing the outer ends of the first stack portion 840a defines the track width or horizontal width of the first stack portion 840a. Figure 8C In this structure, thin insulating material layers 832a and 832b are deposited over the first top surface 802a and the second top surface 802b of the first shield 822a and surrounding the first FL 806 and GL 810. Another thin insulating material layer 832e is disposed around the first optoelectronic template 834a. Furthermore, a first soft bias layer 824c and a second soft bias layer 824d are deposited over the insulating layers 832a and 832b and in front of the refill layers 836a and 836b. The insulating layers 832a and 832b, configured to contact the first SHL 802, the first FL 806, and the GL 810, are removed (e.g., by milling). Figure 8D In the process, a thin layer of insulating material 832 is removed (e.g., by milling).

[0084] exist Figure 8E In the process, the first optoelectronic template 834a is removed, and the materials of the attached first soft bias layer 824c and second soft bias layer 824d are deposited around and in contact with the first SHL 802 and GL 810. Figure 8F In this configuration, an additional GL 810 is optionally deposited on the remaining GL 810 and soft bias layers 824c and 824d (collectively referred to as soft bias layer 824). A second SHL 804 is deposited on GL 810. A second FL 808 is deposited on the second SHL 804, and a second insulating layer 820a is deposited on the second FL 808. A second opto-stencil 834b is deposited on the second insulating layer 820a above the second stack portion 840b, defining the track width of the second stack portion 840b. The track width of the second stack portion 840b is equal to the track width of the first stack portion 840a.

[0085] exist Figure 8GIn this process, additional insulating material 832f is deposited on the exposed top surfaces of the first soft bias layer 824c and the second soft bias layer 824d, and surrounds the second stack portion 840b and the second optoelectronic template 834b. Then, portions of GL 810, the second SHL 804, the second FL 808, and the second insulating layer 820a that are not covered by the second optoelectronic template 834b (i.e., the outer ends of the second stack portion 840b) are removed. The remaining portion of the second stack portion 840b and the first stack portion 840a together form a stack 840.

[0086] exist Figure 8H In this process, the additional insulating material 832f located on top of the second photoelectric template 834b is removed, such that the first insulating layer 832c remains disposed on one side of the second stacked portion 840b, and the second insulating layer 832d remains disposed on the opposite side of the second stacked portion 840b. Figure 8I In this process, an additional soft bias layer 824 is deposited on top of previously deposited soft bias layers 824c and 824d, wherein the top surface of the soft bias layer 824 is flush with the top surface of the second insulating layer 820a. An AFM / capping layer 826 is deposited on the first soft bias layer 824c and the second soft bias layer 824d, and surrounds the thin insulating layers 832c and 832d. Furthermore, the AFM / capping layer 826 is deposited around and on the second optoelectronic template 834b.

[0087] exist Figure 8J In this process, a portion of the second optoelectronic template 834b and the AFM / capping layer 826 is removed, aligning the top surface of the AFM / capping layer 826 with the second insulating layer 820a. Figure 8K In this process, an additional second insulating layer 820b is deposited on the second insulating layer 820a to form a uniform second insulating layer 820, and is deposited above the AFM / capping layer 826. After defining the strip height and track width of the SOT differential reader 700, the uniform insulating layer 820 is deposited. Portions of the uniform insulating layer 820 may be etched to expose the electrical contacts of the SOT differential reader 700, similar to those described above in other embodiments. Figure 8L In the middle, the second shielding element 822b is deposited on the second insulating layer 820.

[0088] Figures 9A to 9L The formation and definition according to one embodiment are shown. Figure 7A A method for determining the track width of a SOT differential reader 700 with a hard bias layer. Figures 9A to 9L A cross-sectional side view of the SOT differential reader 700 during its manufacture is shown. Although in Figures 9A to 9L Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 700 is the same as described above. Figure 3C and Figure 7A The materials described herein are the same. Figure 9A In the first shield 922a, a first FL 906 is deposited on the first SHL 902, and a GL 910 is deposited on the first FL 906 to form the first portion 940a of the stack 940.

[0089] exist Figure 9B In this process, a first photoresist or photo-stencil 934a is deposited on GL 910 above the first stack portion 940a to define the track width of the first stack portion 940a. Then, the portions of GL 910, the first SHL 902, and the first FL 906 that are not covered by the first photo-stencil 934a (i.e., the outer ends of the first stack portion 940a) are removed to expose the refill layers 936a and 936b disposed behind the first stack portion 940a. Removing the outer ends of the first stack portion 940a defines the track width or horizontal width of the first stack portion 940a. Figure 9C In this structure, thin layers of insulating material 932a, 932b, and 932e are deposited on the first top surface 902a and the second top surface 902b of the first shield 922a, and surround the first FL 906, the first SHL 902, the GL 910, and the first optoelectronic template 934a. Furthermore, a first hard bias layer 924a and a second hard bias layer 924b are deposited on the insulating materials 932a and 932b and in front of the refill layers 936a and 936b. Figure 9D In the process, the insulating layers 932a and 932b that are configured to contact the first SHL 902, GL 910, and the first optoelectronic template 934a are removed (e.g., by milling). The insulating layers 932a and 932b that are configured to contact the first FL 906 and the first shield 922a are retained.

[0090] exist Figure 9E In the process, the first optoelectronic template 934a is removed, and the materials of the additional first hard bias layer 924a and second hard bias layer 924b are deposited around and in contact with the first SHL 902 and GL 910. Figure 9F Optionally, additional GL 910 material is deposited on the previously deposited GL 910 and on hard bias layers 924a, 924b (collectively referred to as hard bias layer 924). A second SHL 904 is deposited on GL 910, a second FL 908 is deposited on the second SHL 904, and a second insulating layer 920a is deposited on the second FL 908 to form a second portion 940b of the stack 940. A second opto-stencil 934b is deposited on the second insulating layer 920a above the second stack portion 940b to define the track width of the second stack portion 940b. The track width of the second stack portion 940b is equal to the track width of the first stack portion 940a.

[0091] exist Figure 9G Then, the portions of GL 910, the second SHL 904, the second FL 908, and the second insulating layer 920a that are not covered by the second optoelectronic template 934b (i.e., the outer ends of the second stack portion 940b) are removed. The remaining portions of the second stack portion 940b and the first stack portion 940a together form a stack 840. Figure 9H In this process, additional insulating material 932f is deposited on the exposed top surfaces of the first hard bias layer 924a and the second hard bias layer 924b. Additional insulating material 932f is also deposited around the second stack portion 940b and the second optoelectronic template 934b. Figure 9H In the process, the additional insulating material 932f located on the top of the second photoelectric template 934b is removed, so that the first insulating layer 932c is disposed on one side of the second stack portion 940b, adjacent to the first hard bias layer 924a, and the second insulating layer 932d is disposed on the opposite side of the second stack portion 940b, adjacent to the second hard bias layer 824b.

[0092] exist Figure 9I In this process, an additional hard bias layer 924 is deposited on top of previously deposited hard bias layers 924a and 924b, with the top surfaces of hard bias layers 924a and 924b aligned with the top surface of the second insulating layer 920a. An additional hard bias layer 926 is deposited on the first hard bias layer 924a and the second hard bias layer 924b and surrounds the thin insulating layers 932c and 932d. Furthermore, the additional hard bias layer 926 is deposited on top of and around the second optoelectronic template 934b. Figure 9J In this process, the portion of the second photoelectric template 934b and the additional hard bias layer 926 that was configured to contact the second photoelectric template 934b (e.g., the additional hard bias layer 926 disposed above the top surface of the second insulating layer 920a) is removed. The top or exposed surface of the additional hard bias layer 926 is aligned with the second insulating layer 920a to form a uniformly flat surface.

[0093] exist Figure 9K In this process, an additional second insulating layer 920b is deposited on the second insulating layer 920a to form a uniform second insulating layer 920, and is deposited on the additional hard bias layer 926. After defining the strip height and track width of the SOT differential reader 700, the uniform insulating layer 920 is deposited. Portions of the uniform insulating layer 920 may be etched to expose the electrical contacts of the SOT differential reader 700, similar to those described above in other embodiments. Figure 9L In the middle, the second shielding element 922b is deposited on the second insulating layer 920.

[0094] Figures 10A to 10HThe formation and definition according to one embodiment are shown. Figure 7B Method for determining the height of a bar in a SOT differential reader 700. Figures 10A to 10H A cross-sectional side view of the SOT differential reader 700 during its manufacture is shown. Although in Figures 10A to 10H Different reference numerals may be used in the accompanying drawings, but the material of the layers forming the SOT differential reader 700 is the same as described above. Figure 7B The materials described herein are the same. Figure 10A In the first FL 1002, a first SHL 1006 is deposited on the first FL 1002, and a GL 1010 is deposited on the first SHL 1006 to form the first portion 1040a of the stack 1040.

[0095] exist Figure 10B In the process, a first photoresist or photoresist 1034a is deposited over the first stack portion 1040a. Then, the portions of the first FL 1002, the first SHL 1006, and the GL 1010 not covered by the first photoresist 1034a (i.e., the back side of the first stack portion 1040a recessed from the MFS 1050) are removed to define the strip height of the first stack portion 1040a. Figure 10C In the process, a first insulating layer 1020a is deposited, wherein the removed portions of the first FL 1002, the first SHL 1006, and the GL 1010 are located within... Figure 10B In the middle (i.e., on the back side of the first stack portion 1040a).

[0096] exist Figure 10D In the process, the first optoelectronic template 1034a is removed, and the second optoelectronic template 1034b is deposited on the first insulating layer 1020a. Then, the track width of the first stacked portion 1040a is defined, as described above. Figures 8A to 8L and Figures 8A to 9L As stated in [the text]. Figure 10E In the process, the second optoelectronic template 1034b is removed, and additional GL 1010 material is deposited on GL 1010 and the first insulating layer 1020a. A second SHL 1008 is deposited on GL 1010, and a second FL 1004 is deposited on the second SHL 1008 to form a second portion 1040b of the stack 1040. The second insulating layer 1020b is disposed on the second FL 1004. The first stack portion 1040a and the second stack portion 1040b together form the stack 1040. The stack 1040 then forms electrical leads for the SOT differential reader 700.

[0097] exist Figure 10FIn this process, a portion of each of GL 1010, the second SHL 1008, and the second FL 1004 is removed using a process such as milling to define the strip height of the second stack portion 1040b. The first stack portion 1040a and the second stack portion 1040b have equal strip heights. The removed portions of GL 1010, the second SHL 1008, and the second FL 1004 can be formed into flat surfaces or planes such that the rear end of the second stack portion 1040b is aligned with the rear end of the first stack portion 1040a. When removing a portion of each of GL 1010, the second SHL 1008, and the second FL 1004, an optoelectronic template (not shown) can be used. An additional insulating layer 1020 is deposited behind the second stack portion 1040b (e.g., where the removed portions of the second stack portion 1040b are located on...). Figure 10E (In the middle). The first insulating layer 1020a and the second insulating layer 1020 form a uniform layer referred to as insulating layer 1020.

[0098] exist Figure 10G In this process, a third optoelectronic template 1034c is deposited on an insulating layer 1020. Once the third optoelectronic template 1034c is deposited, etching can occur to enable one or more electrical lead connections. After defining the strip height and track width of the SOT differential reader 700, a uniform insulating layer 1020 is deposited. Portions of the uniform insulating layer 1020 can be etched to expose the electrical contacts of the SOT differential reader 700, similar to those described above in other embodiments. Figure 10H In the process, the third optoelectronic template 1034c is removed, and the second shielding element 1022b is deposited on the insulating layer 1020.

[0099] By utilizing various SOT differential reader designs, configurations with multiple SHE layers, multiple FLs, and multiple electrical lead connections can be arranged differently, achieving better reader resolution while maintaining shield-to-shield spacing. Therefore, it is not necessary to reduce the shield-to-shield spacing of the shields clamping the SOT differential reader to improve reader resolution, as SOT differential readers allow for wider shield-to-shield spacing without reducing resolution. Increasing the shield-to-shield spacing of the SOT differential reader increases throughput, and the layer strip height of the SOT differential reader can be increased to reduce magnetic noise.

[0100] In one embodiment, the magnetic recording head includes a first shield, a second shield, a first bias layer, a second bias layer, and a SOT differential reader disposed between the first shield and the second shield and between the first bias layer and the second bias layer. The SOT differential reader includes: a first free layer; a second free layer; a first spin Hall effect layer; a second spin Hall effect layer in contact with the first and second bias layers; and one or more insulating layers, wherein the first insulating layer is disposed between the first spin Hall effect layer and the first bias layer, and the second insulating layer is disposed between the first spin Hall effect layer and the second bias layer.

[0101] The magnetic recording head also includes a gap layer, wherein a first spin Hall effect layer is disposed on a first shield, a first free layer is disposed on the first spin Hall effect layer, a gap layer is disposed on the first free layer, a second free layer is disposed on the gap layer, and a second spin Hall effect layer is disposed on the second free layer. The magnetic recording head is configured to receive current injected into the first spin Hall effect layer and output current through the second spin Hall effect layer, wherein a first spin Hall effect voltage is sensed through the second spin Hall effect layer, and a second spin Hall effect voltage is sensed through the first spin Hall effect layer.

[0102] The magnetic recording head also includes a gap layer, wherein a first free layer is disposed on a first shield, a first spin Hall effect layer is disposed on the first free layer, the gap layer is disposed on the first spin Hall effect layer, a second spin Hall effect layer is disposed on the gap layer, and the second free layer is disposed on the second spin Hall effect layer. The positive terminal of the first spin Hall effect layer is electrically connected to the negative terminal of the second spin Hall effect layer, and the voltage difference across the negative terminal of the first spin Hall effect layer to the positive terminal of the second spin Hall effect layer is a signal read from the SOT differential reader. The first bias layer and the second bias layer comprise hard bias materials. The first bias layer and the second bias layer comprise soft bias materials. The first spin Hall effect layer has a longer length than the second spin Hall effect layer in the transtrack direction on the surface facing the medium, and wherein the second shield is an electrically leded connection.

[0103] In another embodiment, the magnetic recording head includes a first shield, a second shield, and a SOT differential reader disposed on a surface facing the medium between the first and second shields. The SOT differential reader includes a first free layer, a second free layer, a gap layer, a first spin Hall effect layer, and a second spin Hall effect layer, wherein the positive terminal of the first spin Hall effect layer is electrically connected to the positive terminal of the second spin Hall effect layer, and the signal read from the SOT differential reader is based on the voltage difference across the negative terminal of the first spin Hall effect layer to the negative terminal of the second spin Hall effect layer.

[0104] A first spin Hall effect layer is disposed on a first shield, a first free layer is disposed on the first spin Hall effect layer, a gap layer is disposed on the first free layer, a second free layer is disposed on the gap layer, and a second spin Hall effect layer is disposed on the second free layer, wherein the first spin Hall effect layer has a longer length than the second spin Hall effect layer on the surface facing the medium in the transtrack direction. A first free layer is disposed on the first shield, a first spin Hall effect layer is disposed on the first free layer, a gap layer is disposed on the first spin Hall effect layer, a second spin Hall effect layer is disposed on the gap layer, and a second free layer is disposed on the second spin Hall effect layer, wherein the SOT differential readout is disposed on the surface facing the medium and has a bar height between about 10 nm and about 40 nm.

[0105] The magnetic recording head further includes: a first hard bias shield, which is disposed adjacent to a first surface of the SOT differential reader and between the first shield and a second shield; a second hard bias shield, which is disposed adjacent to a second surface of the SOT differential reader and between the first shield and the second shield; a first insulating layer, which is disposed between a first spin Hall effect layer and the first hard bias shield; and a second insulating layer, which is disposed between the first spin Hall effect layer and the second hard bias shield. The magnetic recording head further includes: a first soft bias shield disposed adjacent to a first surface of the SOT differential reader and between the first shield and a second shield; a second soft bias shield disposed adjacent to a second surface of the SOT differential reader and between the first shield and the second shield; a first insulating layer disposed between a first spin Hall effect layer and the first soft bias shield; and a second insulating layer disposed between the first spin Hall effect layer and the second soft bias shield. The SOT differential reader includes one or more electrical lead contacts.

[0106] In another embodiment, a method of forming an SOT differential reader includes: depositing a first spin Hall effect layer over a first shield; depositing a first free layer on the first spin Hall effect layer; depositing a gap layer on the first free layer; depositing a second free layer on the gap layer; depositing a second spin Hall effect layer on the second free layer; and depositing a first insulating layer on the second spin Hall effect layer to form a stack; removing a portion of the first spin Hall effect layer, a portion of the first free layer, a portion of the gap layer, a portion of the second free layer, a portion of the second spin Hall effect layer, and a portion of the first insulating layer to define the track width of the stack; depositing a second insulating layer that contacts a first surface, a second surface, and a third surface of the stack, wherein a fourth surface of the stack is a dielectric-facing surface; removing a portion of the second insulating layer that contacts the second spin Hall effect layer; depositing a first bias layer and a second bias layer on the first and second surfaces of the stack, the first bias layer and the second bias layer contacting the second spin Hall effect layer and the first insulating layer; and depositing a second shield over the stack.

[0107] Removing a portion of the first spin Hall effect layer, a portion of the first free layer, a portion of the gap layer, a portion of the second free layer, a portion of the second spin Hall effect layer, and a portion of the first insulating layer further defines the height of the stacked strip.

[0108] In another embodiment, a method of forming a SOT differential reader includes: depositing a first free layer over a first shield, depositing a first spin Hall effect layer on the first free layer, and depositing a gap layer on the first spin Hall effect layer to form a first stack; removing a portion of the first free layer, a portion of the first spin Hall effect layer, and a portion of the gap layer to define a first track width of the first stack; depositing a first insulating layer that contacts a first surface, a second surface, and a third surface of the first stack, wherein a fourth surface of the first stack is disposed at a surface facing the dielectric; and removing the first insulating layer from the first spin Hall effect layer. The portion in contact with the gap layer; depositing a first bias layer in contact with the first spin Hall effect layer, the gap layer, and the first insulating layer; depositing a second spin Hall effect layer on the gap layer and a second free layer on the second spin Hall effect layer to form a second stack on the first stack; removing a portion of the second spin Hall effect layer and a portion of the second free layer to define a second track width of the second stack; depositing a second insulating layer in contact with the first, second, and third surfaces of the second stack, wherein a fourth surface of the second stack is disposed on the surface facing the dielectric; and depositing a second shielding element over the second stack.

[0109] Removing a portion of the first free layer, a portion of the first spin Hall effect layer, and a portion of the gap layer further defines a first height of the first stack. Removing a portion of the second spin Hall effect layer, a portion of the second free layer, and a portion of the second insulating layer further defines a second height of the second stack, the first height being equal to the second height.

[0110] While the foregoing describes embodiments of this disclosure, other and additional embodiments of this disclosure may be contemplated without departing from the basic scope of this disclosure, the scope of which is defined by the appended claims.

Claims

1. A sensing element, the sensing element comprising: First bias layer; Second bias layer; and A spin-orbit torque element is disposed between the first bias layer and the second bias layer, and the spin-orbit torque element includes: First free layer; Second free layer; First spin Hall effect layer; A second spin Hall effect layer, wherein the second spin Hall effect layer is in contact with the first bias layer and the second bias layer; and One or more insulating layers, wherein a first insulating layer is disposed between the first spin Hall effect layer and the first bias layer, and a second insulating layer is disposed between the first spin Hall effect layer and the second bias layer.

2. The sensing element according to claim 1 further includes a gap layer, wherein the first spin Hall effect layer is disposed on the first shield, the first free layer is disposed on the first spin Hall effect layer, the gap layer is disposed on the first free layer, the second free layer is disposed on the gap layer, and the second spin Hall effect layer is disposed on the second free layer.

3. The sensing element of claim 2, wherein the sensing element is configured to receive a current injected into the first spin Hall effect layer and output a current through the second spin Hall effect layer, wherein a first spin Hall effect voltage is sensed through the second spin Hall effect layer and a second spin Hall effect voltage is sensed through the first spin Hall effect layer.

4. The sensing element according to claim 1 further includes a gap layer, wherein the first free layer is disposed on the first shield, the first spin Hall effect layer is disposed on the first free layer, the gap layer is disposed on the first spin Hall effect layer, the second spin Hall effect layer is disposed on the gap layer, and the second free layer is disposed on the second spin Hall effect layer.

5. The sensing element of claim 1, wherein the positive terminal of the first spin Hall effect layer is electrically connected to the negative terminal of the second spin Hall effect layer, and the voltage difference across the negative terminal of the first spin Hall effect layer to the positive terminal of the second spin Hall effect layer is a signal read from the spin orbital torque element.

6. The sensing element of claim 1, wherein the first bias layer and the second bias layer comprise a hard bias material.

7. The sensing element of claim 1, wherein the first bias layer and the second bias layer comprise a soft bias material.

8. The sensing element of claim 1, wherein the first spin Hall effect layer has a longer length in the trans-track direction at the surface facing the medium than the second spin Hall effect layer, and wherein the second shield is an electrical lead connection.

9. A magnetic recording device, the magnetic recording device comprising the sensing element according to claim 1.

10. The magnetic recording apparatus according to claim 9, further comprising: The first shielding component, and The second shielding element is disposed between the first shielding element and the second shielding element.

11. A magnetic recording head, the magnetic recording head comprising: First shielding component; Second shielding component; A spin-orbit torque differential reader, wherein the spin-orbit torque differential reader is disposed on the surface facing the medium between the first shield and the second shield, the spin-orbit torque differential reader comprising: First free layer; Second free layer; Interstitial layer; First spin Hall effect layer; and A second spin Hall effect layer, wherein the positive terminal of the first spin Hall effect layer is electrically connected to the positive terminal of the second spin Hall effect layer, and the signal read from the spin-orbit torque differential reader is based on the voltage difference across the negative terminal of the first spin Hall effect layer to the negative terminal of the second spin Hall effect layer; and The spin-orbit torque differential reader is disposed between the first bias layer and the second bias layer.

12. The magnetic recording head of claim 11, wherein the first spin Hall effect layer is disposed on the first shield, the first free layer is disposed on the first spin Hall effect layer, the gap layer is disposed on the first free layer, the second free layer is disposed on the gap layer, and the second spin Hall effect layer is disposed on the second free layer, and wherein the first spin Hall effect layer has a longer length than the second spin Hall effect layer at the surface facing the medium in the cross-track direction.

13. The magnetic recording head of claim 11, wherein the first free layer is disposed on the first shield, the first spin Hall effect layer is disposed on the first free layer, the gap layer is disposed on the first spin Hall effect layer, the second spin Hall effect layer is disposed on the gap layer, and the second free layer is disposed on the second spin Hall effect layer, and wherein the spin-orbit torque differential reader is disposed on the surface facing the medium and has a bar height between 10 nm and 40 nm.

14. The magnetic recording head according to claim 11, further comprising: A first hard bias shield is disposed adjacent to the first surface of the spin-orbit torque differential reader and between the first shield and the second shield. The second hard bias shield is disposed adjacent to the second surface of the spin orbit torque differential reader and between the first shield and the second shield. A first insulating layer is disposed between the first spin Hall effect layer and the first hard bias shield; and A second insulating layer is disposed between the first spin Hall effect layer and the second hard bias shield.

15. The magnetic recording head according to claim 11, further comprising: A first soft bias shield is disposed adjacent to the first surface of the spin-orbit torque differential reader and between the first shield and the second shield. The second soft bias shield is disposed adjacent to the second surface of the spin orbit torque differential reader and between the first shield and the second shield. A first insulating layer is disposed between the first spin Hall effect layer and the first soft bias shield; and A second insulating layer is disposed between the first spin Hall effect layer and the second soft bias shield.

16. The magnetic recording head of claim 11, wherein the spin-track torque differential reader comprises one or more electrical lead contacts.

17. A magnetic recording device, the magnetic recording device comprising the magnetic recording head according to claim 11.

18. A method for forming a spin-orbit torque differential readout, comprising: A first spin Hall effect layer is deposited above a first shielding element, a first free layer is deposited on the first spin Hall effect layer, a gap layer is deposited on the first free layer, a second free layer is deposited on the gap layer, a second spin Hall effect layer is deposited on the second free layer, and a first insulating layer is deposited on the second spin Hall effect layer to form a stack. A portion of the first spin Hall effect layer, a portion of the first free layer, a portion of the gap layer, a portion of the second free layer, a portion of the second spin Hall effect layer, and a portion of the first insulating layer are removed to define the track width of the stack. A second insulating layer is deposited, which contacts the first, second, and third surfaces of the stack, wherein the fourth surface of the stack is the dielectric-facing surface; Remove the portion of the second insulating layer that contacts the second spin Hall effect layer; A first bias layer and a second bias layer are deposited on the first and second surfaces of the stack, the first bias layer and the second bias layer being in contact with the second spin Hall effect layer and the first insulating layer; as well as A second shield is deposited on top of the stack; and The spin orbit torque differential reader is disposed between the first bias layer and the second bias layer.

19. The method of claim 18, wherein removing a portion of the first spin Hall effect layer, a portion of the first free layer, a portion of the gap layer, a portion of the second free layer, a portion of the second spin Hall effect layer, and a portion of the first insulating layer further defines the strip height of the stack.

20. A method for forming a spin-orbit torque differential readout, comprising: A first free layer is deposited above a first shielding element, a first spin Hall effect layer is deposited on the first free layer, and a gap layer is deposited on the first spin Hall effect layer to form a first stack; A portion of the first free layer, a portion of the first spin Hall effect layer, and a portion of the gap layer are removed to define the first track width of the first stack; A first insulating layer is deposited, the first insulating layer being in contact with a first surface, a second surface, and a third surface of the first stack, wherein a fourth surface of the first stack is disposed on the surface facing the medium; Remove the portion of the first insulating layer that contacts the first spin Hall effect layer and the gap layer; A first bias layer is deposited, which is in contact with the first spin Hall effect layer, the gap layer, and the first insulating layer; A second spin Hall effect layer is deposited on the interstitial layer, and a second free layer is deposited on the second spin Hall effect layer to form a second stack on the first stack; A portion of the second spin Hall effect layer and a portion of the second free layer are removed to define the second track width of the second stack; A second insulating layer is deposited, the second insulating layer being in contact with a first surface, a second surface, and a third surface of the second stack, wherein a fourth surface of the second stack is disposed on the surface facing the medium; as well as A second shield is deposited on top of the second stack.

21. The method of claim 20, wherein removing a portion of the first free layer, a portion of the first spin Hall effect layer, and a portion of the gap layer further defines a first height of the first stack, and wherein removing a portion of the second spin Hall effect layer, a portion of the second free layer, and a portion of the second insulating layer further defines a second height of the second stack, the first height being equal to the second height.

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