U.S. patent application number 15/976684 was filed with the patent office on 2019-09-12 for spin-orbit torque induced magnetization switching in a magnetic recording head.
The applicant listed for this patent is Western Digital Technologies, Inc.. Invention is credited to Kuok San HO, Zhanjie LI, Suping SONG.
Application Number | 20190279665 15/976684 |
Document ID | / |
Family ID | 59738505 |
Filed Date | 2019-09-12 |
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United States Patent
Application |
20190279665 |
Kind Code |
A1 |
LI; Zhanjie ; et
al. |
September 12, 2019 |
SPIN-ORBIT TORQUE INDUCED MAGNETIZATION SWITCHING IN A MAGNETIC
RECORDING HEAD
Abstract
The present disclosure generally relates to magnetic media
devices, and more specifically, to a magnetic media drive employing
a magnetic recording head. The recording head includes a main pole,
a trailing shield hot seed layer, a spin Hall layer disposed
between the main pole and the trailing shield hot seed layer, and a
spin-torque layer disposed between the main pole and the trailing
shield hot seed layer. Spin-orbit torque (SOT) is generated from
the spin Hall layer. The spin-torque layer magnetization switching
or precession is induced by the SOT. The SOT based head reduces the
switching current and the V.sub.jump due to higher spin
polarization ratio, which improves energy efficiency. In addition,
the spin Hall layer and the spin-torque layer are easier to form
compared to the conventional pseudo spin-valve structure.
Inventors: |
LI; Zhanjie; (Pleasanton,
CA) ; SONG; Suping; (Fremont, CA) ; HO; Kuok
San; (Redwood City, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Western Digital Technologies, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
59738505 |
Appl. No.: |
15/976684 |
Filed: |
May 10, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15379226 |
Dec 14, 2016 |
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15976684 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/3146 20130101;
G11B 5/314 20130101; G11B 5/3116 20130101; G11B 5/372 20130101;
G11B 5/374 20130101; G11B 5/315 20130101; G11B 5/37 20130101; G11B
5/3133 20130101; G11B 5/3143 20130101; G11B 2005/0024 20130101 |
International
Class: |
G11B 5/31 20060101
G11B005/31; G11B 5/37 20060101 G11B005/37 |
Claims
1. A magnetic recording head, comprising: a main pole; a trailing
shield hot seed layer; a spin Hall layer disposed between the main
pole and the trailing shield hot seed layer, wherein the spin Hall
layer is recessed from a media facing surface; and a spin-torque
layer disposed between the main pole and the trailing shield hot
seed layer, wherein the spin-torque layer includes a surface at the
media facing surface.
2. The magnetic recording head of claim 1, wherein the spin Hall
layer comprises beta phase Tantalum, beta phase tungsten, platinum,
hafnium, an alloy of tungsten with hafnium, iridium, or bismuth
doped copper, (Bi,Sb)Te, MnIr, XMn (X.dbd.Fe, Pd, Ir, and Pt), or
antiferromagnets.
3. The magnetic recording head of claim 1, wherein the spin-torque
layer is coupled to the spin Hall layer.
4. The magnetic recording head of claim 1, wherein the spin-torque
layer has a height ranging from about 3 nm to about 25 nm and a
thickness ranging from about 1.5 nm to about 15 nm.
5. The magnetic recording head of claim 4, wherein the spin Hall
layer has a height ranging from about 5 nm to about 25 nm and a
thickness ranging from about 2.5 nm to about 100 nm.
6. The magnetic recording head of claim 5, wherein the height of
the spin Hall layer is greater than the height of the spin-torque
layer.
7. The magnetic recording head of claim 1, wherein the spin Hall
layer has a width that is greater than a width of the main pole at
the media facing surface.
8. The magnetic recording head of claim 1, wherein the spin Hall
layer has a width that is greater than a width of the spin-torque
layer.
9. A magnetic recording head, comprising: a trailing shield hot
seed layer; a leading shield; a main pole, wherein the main pole
includes a first surface at a media facing surface, a second
surface facing the trailing shield hot seed layer, a third surface
opposite the second surface, a fourth surface connecting the second
surface and the third surface, and a fifth surface opposite the
fourth surface; a spin Hall structure recessed from the media
facing surface, wherein the spin Hall structure surrounds at least
three surfaces of the second, third, fourth and fifth surfaces of
the main pole; and a spin-torque structure coupled to the spin Hall
structure, wherein the spin-torque structure surrounds at least
three surfaces of the second, third, fourth and fifth surfaces of
the main pole at the media facing surface.
10. The magnetic recording head of claim 9, wherein the spin Hall
structure comprises beta phase Tantalum, beta phase tungsten,
platinum, hafnium, an alloy of tungsten with hafnium, iridium, or
bismuth doped copper, (Bi,Sb)Te, MnIr, XMn (X.dbd.Fe, Pd, Ir, and
Pt), or antiferromagnets.
11. The magnetic recording head of claim 9, wherein the spin-torque
structure has a thickness ranging from about 1.5 nm to about 15
nm.
12. The magnetic recording head of claim 11, wherein the spin Hall
structure has a thickness ranging from about 2.5 nm to about 100
nm.
13. The magnetic recording head of claim 9, wherein the spin-torque
structure and the spin Hall structure surround the second, fourth
and fifth surfaces of the main pole.
14. The magnetic recording head of claim 9, wherein the spin-torque
structure and the spin Hall structure surround the second, third,
fourth and fifth surfaces of the main pole.
15. A data storage device, comprising: a magnetic recording head,
comprising: a main pole; a trailing shield hot seed layer; a spin
Hall layer disposed between the main pole and the trailing shield
hot seed layer, wherein the spin Hall layer is recessed from a
media facing surface; and a spin-torque layer disposed between the
main pole and the trailing shield hot seed layer, wherein the
spin-torque layer includes a surface at the media facing
surface.
16. The data storage device of claim 15, wherein the spin Hall
layer comprises beta phase Tantalum, beta phase tungsten, platinum,
hafnium, an alloy of tungsten with hafnium, iridium, or bismuth
doped copper, (Bi,Sb)Te, MnIr, XMn (X.dbd.Fe, Pd, Ir, and Pt), or
antiferromagnets.
17. The data storage device of claim 15, wherein the spin-torque
layer is coupled to the spin Hall layer.
18. The data storage device of claim 15, wherein the spin-torque
layer has a height ranging from about 3 nm to about 25 nm and a
thickness ranging from about 1.5 nm to about 15 nm.
19. The data storage device of claim 18, wherein the spin Hall
layer has a height ranging from about 5 nm to about 25 nm and a
thickness ranging from about 2.5 nm to about 100 nm.
20. The data storage device of claim 19, wherein the height of the
spin Hall layer is the same as or greater than the height of the
spin-torque layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation of U.S. patent
application Ser. No. 15/379,226, filed on Dec. 14, 2016, which is
incorporated by reference herein in its entirety.
BACKGROUND
Field of the Disclosure
[0002] Embodiments of the present disclosure generally relate to
data storage devices, and more specifically, to a magnetic media
drive employing a magnetic recording head.
Description of the Related Art
[0003] Over the past few years, microwave assisted magnetic
recording (MAMR) has been studied as a recording method to improve
the areal density of a magnetic media device, such as a hard disk
drive (HDD). Conventionally, MAMR enabled magnetic recording is
based on spin-transfer torque (STT), which is generated from a
pseudo spin-valve structure. During operation, electrical current
flows from the main pole to the trailing shield hot seed layer, and
the spin-torque layer magnetization switching (or precession) is
induced by the STT.
[0004] The pseudo spin-valve structure is difficult to make, and
high switching current and voltage (V.sub.jump) are utilized during
its operation, leading to a lower level of energy efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] So that the manner in which the above recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this disclosure and are therefore not to be considered limiting of
its scope, for the disclosure may admit to other equally effective
embodiments.
[0006] FIG. 1 is a schematic illustration of a magnetic media
device according to one embodiment.
[0007] FIG. 2 is a fragmented, cross sectional side view of a
read/write head facing a magnetic disk according to one
embodiment.
[0008] FIG. 3A is a perspective view of a portion of a magnetic
write head of FIG. 2 according to one embodiment.
[0009] FIG. 3B is a MFS view of the portion of the magnetic write
head shown in FIG. 3 according to one embodiment.
[0010] FIG. 4 is a perspective view of a portion of a magnetic
write head of FIG. 2 according to another embodiment.
[0011] FIG. 5 is a perspective view of a portion of a magnetic
write head of FIG. 2 according to another embodiment.
[0012] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0013] The present disclosure generally relates to data storage
devices, and more specifically, to a magnetic media drive employing
a magnetic recording head. The head includes a main pole, a
trailing shield hot seed layer, a spin Hall layer disposed between
the main pole and the trailing shield hot seed layer, and a
spin-torque layer disposed between the main pole and the trailing
shield hot seed layer. Spin-orbit torque (SOT) is generated from
the spin Hall layer. The spin-torque layer magnetization switching
(or precession) is induced by the SOT. The SOT based head reduces
the switching current and the V.sub.jump due to higher spin
polarization ratio, which improves energy efficiency. In addition,
the spin Hall layer and the spin-torque layer are easier to form
compared to the conventional pseudo spin-valve structure.
[0014] The terms "over," "under," "between," and "on" as used
herein refer to a relative position of one layer with respect to
other layers. As such, for example, one layer disposed over or
under another layer may be directly in contact with the other layer
or may have one or more intervening layers. Moreover, one layer
disposed between layers may be directly in contact with the two
layers or may have one or more intervening layers. In contrast, a
first layer "on" a second layer is in contact with the second
layer. Additionally, the relative position of one layer with
respect to other layers is provided assuming operations are
performed relative to a substrate without consideration of the
absolute orientation of the substrate.
[0015] FIG. 1 is a schematic illustration of a data storage device
such as a magnetic media device. Such a data storage device may be
a single drive/device or comprise multiple drives/devices. For the
sake of illustration, a single disk drive 100 is shown according to
one embodiment. As shown, at least one rotatable magnetic disk 112
is supported on a spindle 114 and rotated by a drive motor 118. The
magnetic recording on each magnetic disk 112 is in the form of any
suitable patterns of data tracks, such as annular patterns of
concentric data tracks (not shown) on the magnetic disk 112.
[0016] At least one slider 113 is positioned near the magnetic disk
112, each slider 113 supporting one or more magnetic head
assemblies 121 that may include a spin Hall layer for generating
SOT. As the magnetic disk 112 rotates, the slider 113 moves
radially in and out over the disk surface 122 so that the magnetic
head assembly 121 may access different tracks of the magnetic disk
112 where desired data are written. Each slider 113 is attached to
an actuator arm 119 by way of a suspension 115. The suspension 115
provides a slight spring force which biases the slider 113 toward
the disk surface 122. Each actuator arm 119 is attached to an
actuator means 127. The actuator means 127 as shown in FIG. 1 may
be a voice coil motor (VCM). The VCM includes a coil movable within
a fixed magnetic field, the direction and speed of the coil
movements being controlled by the motor current signals supplied by
control unit 129.
[0017] During operation of the disk drive 100, the rotation of the
magnetic disk 112 generates an air bearing between the slider 113
and the disk surface 122 which exerts an upward force or lift on
the slider 113. The air bearing thus counter-balances the slight
spring force of suspension 115 and supports slider 113 off and
slightly above the disk surface 122 by a small, substantially
constant spacing during normal operation.
[0018] The various components of the disk drive 100 are controlled
in operation by control signals generated by control unit 129, such
as access control signals and internal clock signals. Typically,
the control unit 129 comprises logic control circuits, storage
means and a microprocessor. The control unit 129 generates control
signals to control various system operations such as drive motor
control signals on line 123 and head position and seek control
signals on line 128. The control signals on line 128 provide the
desired current profiles to optimally move and position slider 113
to the desired data track on disk 112. Write and read signals are
communicated to and from write and read heads on the assembly 121
by way of recording channel 125.
[0019] The above description of a typical magnetic media device and
the accompanying illustration of FIG. 1 are for representation
purposes only. It should be apparent that magnetic media devices
may contain a large number of media, or disks, and actuators, and
each actuator may support a number of sliders.
[0020] FIG. 2 is a fragmented, cross sectional side view of a
read/write head 200 facing the magnetic disk 112 according to one
embodiment. The read/write head 200 may correspond to the magnetic
head assembly 121 described in FIG. 1. The read/write head 200
includes a media facing surface (MFS) 212, such as an air bearing
surface (ABS), facing the disk 112, a magnetic write head 210, and
a magnetic read head 211. As shown in FIG. 2, the magnetic disk 112
moves past the write head 210 in the direction indicated by the
arrow 232 and the read/write head 200 moves in the direction
indicated by the arrow 234.
[0021] In some embodiments, the magnetic read head 211 is a
magnetoresistive (MR) read head that includes an MR sensing element
204 located between MR shields S1 and S2. In other embodiments, the
magnetic read head 211 is a magnetic tunnel junction (MTJ) read
head that includes a MTJ sensing device 204 located between MR
shields S1 and S2. The magnetic fields of the adjacent magnetized
regions in the magnetic disk 112 are detectable by the MR (or MTJ)
sensing element 204 as the recorded bits.
[0022] The write head 210 includes a leading shield 206, a main
pole 220, a trailing shield 240, a spin-torque layer 250, a spin
Hall layer 252, and a coil 218 that excites the main pole 220. The
coil 218 may have a "pancake" structure which winds around a
back-contact between the main pole 220 and the trailing shield 240,
instead of a "helical" structure shown in FIG. 2A. The spin-torque
layer 250 and the spin Hall layer 252 are disposed between the main
pole 220 and the trailing shield 240. A trailing shield hot seed
layer 241 may be coupled to the trailing shield 240, and the
trailing shield hot seed layer 241 may face the spin-torque layer
250 and the spin Hall layer 252. The space between the spin-torque
layer 250 (including the spin Hall layer 252) and the main pole 220
is filled with a dielectric material 254, such as alumina. The
dielectric material 254 is also disposed between the spin-torque
layer 250 (including the spin Hall layer 252) and the trailing
shield hot seed layer 241, and between the leading shield 206 and
the main pole 220. The main pole 220 may be a magnetic material
such as a FeCo alloy. The trailing shield 240 may be a magnetic
material such as NiFe alloy. The trailing shield hot seed layer 241
may include a high moment sputter material, such as CoFeN or FeXN,
where X includes at least one of Rh, Al, Ta, Zr, and Ti.
[0023] The spin-torque layer 250 may be a magnetic material, such
as a soft magnetic material, for example CoFe alloy, NiFe alloy,
CoFeB alloy or half-metals. The spin Hall layer 252 may be a heavy
metal, such as beta phase Tantalum (.beta.-Ta), beta phase tungsten
(.beta.-W), platinum (Pt), hafnium (Hf), a heavy metal alloy of
tungsten with hafnium, iridium, or bismuth doped copper, a
topological insulator such as a (Bi,Sb)Te, or antiferromagnetic
materials such as MnIr, XMn (X.dbd.Fe, Pd, Ir, and Pt) and
Cu--Au--I type antiferromagnets. In some embodiments, the spin Hall
layer 252 may be coupled to the spin-torque layer 250 (i.e., the
spin Hall layer 252 may be in direct contact with the spin-torque
layer 250). In some embodiments, one or more intervening layers may
be disposed between the spin Hall layer 252 and the spin-torque
layer 250. During operation, an electrical current flows through
the spin Hall layer 252, which has strong spin-orbit coupling, and
the spin Hall layer 252 generates SOT. The SOT generated by the
spin Hall layer 252 induces magnetization switching (or precession)
of the spin-torque layer 250. In some embodiments, the SOT based
head has an effective spin injection efficiency (.beta.) of about
0.3 to 1.75, about 3 to 12 times larger than that of a head using a
pseudo spin-valve structure (having an effective spin injection
efficiency (.beta.) of about 0.1 to 0.30). Higher effective spin
injection efficiency leads to reduced critical switching current
density, which is defined by the formula:
J CO .apprxeq. 2 e .mu. 0 M S t .alpha. ( H C + M eff / 2 ) /
.beta. ##EQU00001##
Based on this formula, the 3 to 12 times increase in effective spin
injection efficiency (.beta.) for the SOT based head leads to a
reduction of the critical switching current density by 3 to 12
times, which in turn brings a higher energy efficiency (about 3 to
12 times less energy used than that of a head using a pseudo
spin-valve structure).
[0024] FIG. 3A is a perspective view of a portion of the magnetic
write head 210 of FIG. 2 according to one embodiment. As shown in
FIG. 3A, the magnetic write head 210 includes the main pole 220,
the trailing shield hot seed layer 241, the spin-torque layer 250
disposed between the trailing shield hot seed layer 241 and the
main pole 220, and the spin Hall layer 252 disposed between the
trailing shield hot seed layer 241 and the main pole 220. The
dielectric material 254 is omitted for clarity. The main pole 220
includes a first surface 304 and a second surface 305 adjacent the
first surface 304. The first surface 304 may be at the MFS 212 and
the second surface 305 may face the spin-torque layer 250 and the
spin Hall layer 252. The spin-torque layer 250 includes a first
surface 306 at the MFS 212, and the spin-torque layer 250 is
coupled to a first surface 308 of the spin Hall layer 252. The spin
Hall layer 252 is recessed from the MFS 212. In other words, no
portion of the spin Hall layer 252 is at the MFS 212.
[0025] The spin-torque layer 250 has a height H.sub.1 in the Y
direction (down-track direction) ranging from about 3 nm to about
25 nm, a thickness T.sub.1 in the Z direction ranging from about
1.5 nm to about 15 nm, such as about 3 nm, and a width W.sub.1 in
the X direction (cross-track direction). The spin Hall layer 252
has a height H.sub.2 in the Y direction ranging from about 5 nm to
about 25 nm (which is less than the write gap, defined by the
distance between the second surface 305 of the main pole 220 to the
trailing shield hot seed layer 241), a thickness T.sub.2 in the Z
direction ranging from about 2.5 nm to about 100 nm, and a width
W.sub.2 in the X direction. In one embodiment, the spin Hall layer
252 is thicker than the spin-torque layer 250. In one embodiment,
the spin Hall layer 252 is thinner than the spin-torque layer 250.
In one embodiment, the width of the spin-torque layer 250 is the
same as or smaller than the width of the spin Hall layer 252. In
one embodiment, the height of the spin-torque layer 250 is the same
as or smaller than the height of the spin Hall layer 252. During
operation of the SOT based head, the electrical current flows from
the preamp (not shown) to and through the spin Hall layer 252 in
the X direction. By contrast, during operation of a head that uses
a pseudo spin-valve structure, the electrical current flows from
the main pole to the trailing shield, i.e. , in the Y
direction.
[0026] FIG. 3B is a MFS view of the portion of the magnetic write
head 210 shown in FIG. 3A according to one embodiment. As shown in
FIG. 3B, the spin Hall layer 252 includes a second surface 310
facing the second surface 305 of the main pole 220 and a third
surface 312 facing a surface 314 of the trailing shield hot seed
layer 241. The second surface 305 of the main pole 220 and the
second surface 310 of the spin Hall layer 252 are separated by a
distance D.sub.1, and the surface 314 of the trailing shield hot
seed layer 241 and the third surface 312 of the spin Hall layer 252
is separated by a distance D.sub.2. The dielectric material 254
(FIG. 2) may be disposed between the second surface 305 of the main
pole 220 and the second surface 310 of the spin Hall layer 252 and
between the surface 314 of the trailing shield hot seed layer 241
and the third surface 312 of the spin Hall layer 252. In one
embodiment, the distance D.sub.1 is the same as the distance
D.sub.2. In one embodiment, the distance D.sub.1 is about 2 nm and
the distance D.sub.2 is about 2 nm. In one embodiment, the distance
D.sub.1 is not the same as the distance D.sub.2.
[0027] The spin-torque layer 250 includes a second surface 316
facing the second surface 305 of the main pole 220 and a third
surface 318 facing the surface 314 of the trailing shield hot seed
layer 241. The second surface 316 and the third surface 318 of the
spin-torque layer 250 may be in contact with the first surface 308
of the spin Hall layer 252. The second surface 316 may be in
contact with the first surface 308 of the spin Hall layer 252 at a
location on the first surface 308 that is a distance D.sub.3 away
from the second surface 310 of the spin Hall layer 252. The third
surface 318 may be in contact with the first surface 308 of the
spin Hall layer 252 at a location on the first surface 308 that is
a distance D.sub.4 away from the third surface 312 of the spin Hall
layer 252. In one embodiment, the distance D.sub.3 is the same as
the distance D.sub.4. In one embodiment, the distance D.sub.3 is
about 2 nm and the distance D.sub.4 is about 2 nm. In one
embodiment, the distance D.sub.3 is not the same as the distance
D.sub.4.
[0028] The width W.sub.2 of the spin Hall layer 252 may be greater
than the width W.sub.3 of the main pole 220 at the MFS 212. The
width W.sub.1 of the spin-torque layer 250 may be the same, smaller
than, or greater than the width W.sub.3 of the main pole 220 at the
MFS 212.
[0029] FIG. 4 is a perspective view of a portion of the magnetic
write head 210 of FIG. 2 according to another embodiment. As shown
in FIG. 4, the main pole 220 includes the first surface 304 at the
MFS 212, the second surface 305 adjacent the first surface 304, a
third surface 402 opposite the second surface 305, a fourth surface
404 connecting the third surface 402 and the second surface 305,
and a fifth surface 406 opposite the fourth surface 404. The main
pole 220 at the MFS 212 may be surrounded by a spin-torque
structure 408. The spin-torque structure 408 may surround at least
three surfaces of the first, second, third, fourth, and fifth
surfaces 304, 305, 402, 404, 406. In one embodiment, the
spin-torque structure 408 surrounds the second surface 305, the
third surface 402, the fourth surface 404, and the fifth surface
406. The spin-torque structure 408 may be made of the same material
as the spin-torque layer 250 and may replace the spin-torque layer
250 shown in FIG. 2. The spin-torque structure 408 is coupled to a
spin Hall structure 410 recessed from the MFS 212. The spin Hall
structure 410 surrounds the main pole 220 at locations recessed
from the MFS 212. The spin Hall structure 410 may surround at least
three surfaces of the first, second, third, fourth, and fifth
surfaces 304, 305, 402, 404, 406. In one embodiment, the spin Hall
structure 410 surrounds the second surface 305, the third surface
402, the fourth surface 404, and the fifth surface 406. The spin
Hall structure 410 may be made of the same material as the spin
Hall layer 252 and may replace the spin Hall layer 252 shown in
FIG. 2. During operation, electrical current I.sub.1 flows from the
preamp (not shown) to the spin Hall structure 410, and the
electrical current I.sub.1 may flow through the spin Hall structure
410 in a clockwise direction, as shown in FIG. 4. The spin Hall
structure 410 generates SOT, which induces magnetization switching
(or precession) of the spin-torque structure 408. The spin-torque
structure 408 may have a thickness T.sub.3 in the Z direction
ranging from about 1.5 nm to about 15 nm. The spin Hall structure
410 may have a thickness T.sub.4 in the Z direction ranging from
about 2.5 nm to about 100 nm. In one embodiment, the thickness
T.sub.4 of the spin Hall structure 410 is greater than the
thickness T.sub.3 of the spin-torque structure.
[0030] The spin-torque structure 408 may include a first portion
412, a second portion 416 opposite the first portion 412, a third
portion 414 connecting the first portion 412 and the second portion
416, and a fourth portion 418 opposite the third portion 414. The
first portion 412 may be substantially parallel to the second
surface 305 of the main pole 220. The second portion 416 may be
substantially parallel to the third surface 402 of the main pole
220. The third portion 414 may be substantially parallel to the
fourth surface 404 of the main pole 220. The fourth portion 418 may
be substantially parallel to the fifth surface 406 of the main pole
220. A dielectric material, such as the dielectric material 254
shown in FIG. 2, may be disposed between each portion 412, 416,
414, 418 and a corresponding surface of the surfaces 305, 402, 404,
406.
[0031] The spin Hall structure 410 may include a first portion 420,
a second portion 424 opposite the first portion 420, a third
portion 422 connecting the first portion 420 and the second portion
424, and a fourth portion 426 opposite the third portion 422. The
first portion 420 of the spin Hall structure 410 may be coupled to
the first portion 412 of the spin-torque structure 408, the second
portion 424 of the spin Hall structure 410 may be coupled to the
second portion 416 of the spin-torque structure 408, the third
portion 422 of the spin Hall structure 410 may be coupled to the
third portion 414 of the spin-torque structure 408, and the fourth
portion 426 of the spin Hall structure 410 may be coupled to the
fourth portion 418 of the spin-torque structure 408. Each portion
420, 424, 422, 426 of the spin Hall structure 410 has a width in
the X direction and a height in the Y direction, and each portion
412, 416, 414, 418 of the spin-torque structure 408 has a width in
the X direction and a height in the Y direction. The width of each
portion 420, 424, 422, 426 of the spin Hall structure 410 may be
greater than the width of a corresponding portion of the
spin-torque structure 408. The height of each portion 420, 424,
422, 426 of the spin Hall structure 410 may be greater than the
height of a corresponding portion of the spin-torque structure
408.
[0032] FIG. 5 is a perspective view of a portion of the magnetic
write head 210 of FIG. 2 according to another embodiment. As shown
in FIG. 5, the spin-torque structure 408 surrounds the second
surface 305 of the main pole 220, the fourth surface 404 of the
main pole 220, and the fifth surface 406 of the main pole 220. The
spin-torque structure 408 does not surround the third surface 402
of the main pole 220. The spin-torque structure 408 surrounds three
surfaces 305, 404, 406 of the main pole 220 at the MFS 212. The
spin-torque structure 408 includes the first portion 412, a second
portion 502 adjacent the first portion 412, and a third portion 504
opposite the second portion 502. The second portion 502 may be the
same as the second portion 416 shown in FIG. 4, and the third
portion 504 may be the same as the fourth portion 418 shown in FIG.
4. The first portion 412 may be substantially parallel to the
second surface 305 of the main pole 220. The second portion 502 may
be substantially parallel to the fourth surface 404 of the main
pole 220. The third portion 504 may be substantially parallel to
the fifth surface 406 of the main pole 220. A dielectric material,
such as the dielectric material 254 shown in FIG. 2, may be
disposed between each portion 412, 502, 504 and a corresponding
surface of the surfaces 305, 404, 406.
[0033] The spin Hall structure 410 may include the first portion
420, a second portion 506 adjacent the first portion 420, and a
third portion 508 opposite the second portion 506. The first
portion 420 of the spin Hall structure 410 may be coupled to the
first portion 412 of the spin-torque structure 408, the second
portion 506 of the spin Hall structure 410 may be coupled to the
second portion 502 of the spin-torque structure 408, the third
portion 508 of the spin Hall structure 410 may be coupled to the
third portion 504 of the spin-torque structure 408. The second
portion 506 of the spin Hall structure 410 may be the same as the
third portion 422 shown in FIG. 4, and the third portion 508 of the
spin Hall structure 410 may be the same as the fourth portion 426
shown in FIG. 4. The third surface 402 of the main pole 220 is in
contact with the dielectric material 254 (FIG. 2), and the
dielectric material 254 is in contact with the leading shield 206
(FIG. 2). There is no spin Hall layer or spin-torque layer disposed
between the main pole 220 and the leading shield 206 (FIG. 2).
[0034] The spin Hall structure 410 may include a first end 510 and
a second end 512. The first end 510 and the second end 512 are
connected to the preamp (not shown) by leads (not shown). During
operation, electrical current I.sub.2 flows from the preamp to the
first end 510 of the spin Hall structure 410. The electrical
current I.sub.2 flows through the spin Hall structure 410 in a
clockwise direction to the second end 512, as shown in FIG. 5. The
spin Hall structure 410 generates SOT, which induces magnetization
switching (or precession) of the spin-torque structure 408.
[0035] The benefits of having a SOT based head is that the spin
polarization ratio of the SOT based head is about 3 to 12 times
larger than that of a head using a pseudo spin-valve structure,
reducing the critical switching current density by 3 to 12 times.
As a result of the reduced critical switching current density, the
SOT based head has a higher energy efficiency, such as about 3 to
12 times less energy used than that of a head using a pseudo
spin-valve structure. Furthermore, the spin-torque layer and the
spin Hall layer of the SOT based head are easier to form compared
to the conventional pseudo spin-valve structure.
[0036] While the foregoing is directed to embodiments of the
present disclosure, other and further embodiments of the disclosure
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
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