Patent ID: 12230298

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

In the following, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the disclosure. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

Co-owned U.S. Pat. No. 10,366,714 titled “Magnetic write head for providing spin-torque-assisted write field enhancement” (by Olson et al) proposes, among other things, a write head with a spin torque layer between the main pole and trailing shield. The spin torque layer (STL) can be switched to oppose a gap field to enhance the main pole's write field. A thicker STL can increase the amount of field generated by the spin torque layer, but thickening the STL produces practical issues such as rise time and single domain ration reduction that limit scalability.

To address such scalability issues, various embodiments disclosed here propose using two STLs in the gap to oppose the gap field. In some embodiments, one STL is driven by a main pole notch and another STL is driven by a trailing shield notch. In some embodiments, one of the notches comprises a negative beta material such as FeCr. In some embodiments, the two STLs are separated by one or more spin kill layers so no torque is transferred between the two STLs. Some embodiments further include one or more layers of negative beta material placed between the two STLs to further reduce the interaction between them.

The present disclosure is generally related to a magnetic recording device comprising a magnetic recording head. The magnetic recording head comprises a main pole (MP), a shield, and a spintronic device disposed between the MP and the shield. The spintronic device comprises a MP notch disposed on the MP, a first spin torque layer (STL), a second STL, a spin kill layer disposed between the first and second STLs, and a shield notch. The spin kill layer prevents spin torque from being transferred between the first STL and the second STL. In a forward stack where electrons flow from the MP to the shield, the MP notch comprises FeCr and the shield notch comprises CoFe. In a reverse stack where electrons flow from the shield to the MP, the MP notch comprises CoFe and the shield notch comprises FeCr.

FIG.1is a schematic illustration of a magnetic recording device100, according to one implementation. The magnetic recording device100includes a magnetic recording head, such as a write head. The magnetic recording device100is a magnetic media drive, such as a hard disk drive (HDD). Such magnetic media drives may be a single drive/device or include multiple drives/devices. For the ease of illustration, a single disk drive is shown as the magnetic recording device100in the implementation illustrated inFIG.1. The magnet recording device100(e.g., a disk drive) includes at least one rotatable magnetic disk112supported on a spindle114and rotated by a drive motor118. The magnetic recording on each rotatable magnetic disk112is in the form of any suitable patterns of data tracks, such as annular patterns of concentric data tracks on the rotatable magnetic disk112.

At least one slider113is positioned near the rotatable magnetic disk112. Each slider113supports a head assembly121. The head assembly121includes one or more magnetic recording heads (such as read/write heads), such as a write head including a spintronic device. As the rotatable magnetic disk112rotates, the slider113moves radially in and out over the disk surface122so that the head assembly121may access different tracks of the rotatable magnetic disk112where desired data are written. Each slider113is attached to an actuator arm119by way of a suspension115. The suspension115provides a slight spring force which biases the slider113toward the disk surface122. Each actuator arm119is attached to an actuator127. The actuator127as shown inFIG.1may 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 a control unit129.

The head assembly121, such as a write head of the head assembly121, includes a media facing surface (MFS) such as an air bearing surface (ABS) that faces the disk surface122. During operation of the magnetic recording device100, the rotation of the rotatable magnetic disk112generates an air or gas bearing between the slider113and the disk surface122which exerts an upward force or lift on the slider113. The air or gas bearing thus counter-balances the slight spring force of suspension115and supports the slider113off and slightly above the disk surface122by a small, substantially constant spacing during operation.

The various components of the magnetic recording device100are controlled in operation by control signals generated by control unit129, such as access control signals and internal clock signals. The control unit129includes logic control circuits, storage means and a microprocessor. The control unit129generates control signals to control various system operations such as drive motor control signals on a line123and head position and seek control signals on a line128. The control signals on line128provide the desired current profiles to optimally move and position slider113to the desired data track on rotatable magnetic disk112. Write and read signals are communicated to and from the head assembly121by way of recording channel125. In one embodiment, which can be combined with other embodiments, the magnetic recording device100may further include a plurality of media, or disks, a plurality of actuators, and/or a plurality number of sliders.

FIG.2is a schematic illustration of a cross sectional side view of a head assembly200facing the rotatable magnetic disk112shown inFIG.1or other magnetic storage medium, according to one implementation. The head assembly200may correspond to the head assembly121described inFIG.1. The head assembly200includes a media facing surface (MFS)212, such as an air bearing surface (ABS), facing the rotatable magnetic disk112. As shown inFIG.2, the rotatable magnetic disk112relatively moves in the direction indicated by the arrow232and the head assembly200relatively moves in the direction indicated by the arrow234.

In one embodiment, which can be combined with other embodiments, the head assembly200includes a magnetic read head211. The magnetic read head211may include a sensing element204disposed between shields S1and S2. The sensing element204is a magnetoresistive (MR) sensing element, such an element exerting a tunneling magneto-resistive (TMR) effect, a magneto-resistance (GMR) effect, an extraordinary magneto-Resistive (EMR) effect, or a spin torque oscillator (STO) effect. The magnetic fields of magnetized regions in the rotatable magnetic disk112, such as perpendicular recorded bits or longitudinal recorded bits, are detectable by the sensing element204as the recorded bits.

The head assembly200includes a write head210. In one embodiment, which can be combined with other embodiments, the write head210includes a main pole220, a leading shield206, a trailing shield (TS)240, and a spintronic device230disposed between the main pole220and the TS240. The main pole220serves as a first electrode. Each of the main pole220, the spintronic device230, the leading shield206, and the trailing shield (TS)240has a front portion at the MFS.

The main pole220includes a magnetic material, such as CoFe, CoFeNi, or FeNi, other suitable magnetic materials. In one embodiment, which can be combined with other embodiments, the main pole220includes small grains of magnetic materials in a random texture, such as body-centered cubic (BCC) materials formed in a random texture. In one example, a random texture of the main pole220is formed by electrodeposition. The write head210includes a coil218around the main pole220that excites the main pole220to produce a writing magnetic field for affecting a magnetic recording medium of the rotatable magnetic disk112. The coil218may be a helical structure or one or more sets of pancake structures.

In one embodiment, which can be combined with other embodiments, the main pole220includes a trailing taper242and a leading taper244. The trailing taper242extends from a location recessed from the MFS212to the MFS212. The leading taper244extends from a location recessed from the MFS212to the MFS212. The trailing taper242and the leading taper244may have the same degree or different degree of taper with respect to a longitudinal axis260of the main pole220. In one embodiment, which can be combined with other embodiments, the main pole220does not include the trailing taper242and the leading taper244. In such an embodiment, the main pole220includes a trailing side and a leading side in which the trailing side and the leading side are substantially parallel.

The TS240includes a magnetic material, such as FeNi, or other suitable magnetic materials, serving as a second electrode and return pole for the main pole220. The leading shield206may provide electromagnetic shielding and is separated from the main pole220by a leading gap254.

In some embodiments, the spintronic device230is positioned proximate the main pole220and reduces the coercive force of the magnetic recording medium, so that smaller writing fields can be used to record data. In such embodiments, an electron current is applied to spintronic device230from a current source270to produce a microwave field. The electron current may include direct current (DC) waveforms, pulsed DC waveforms, and/or pulsed current waveforms going to positive and negative voltages, or other suitable waveforms. In other embodiments, an electron current is applied to spintronic device230from a current source270to produce a high frequency alternating current (AC) field to the media.

In one embodiment, which can be combined with other embodiments, the spintronic device230is electrically coupled to the main pole220and the TS240. The main pole220and the TS240are separated in an area by an insulating layer272. The current source270may provide electron current to the spintronic device230through the main pole220and the TS240. For direct current or pulsed current, the current source270may flow electron current from the main pole220through the spintronic device230to the TS240or may flow electron current from the TS240through the spintronic device230to the main pole220depending on the orientation of the spintronic device230. In one embodiment, which can be combined with other embodiments, the spintronic device230is coupled to electrical leads providing an electron current other than from the main pole220and/or the TS240.

FIGS.3A-3Dillustrate spintronic devices300,325,350,375, according to various embodiments. Each spintronic device300,325,350, and375may independently be the spintronic device230ofFIG.2, and each spintronic device300,325,350, and375is disposed in a gap between a main pole302, such as the main pole220ofFIG.2, and a shield, such as the trailing shield240ofFIG.2, a leading shield206ofFIG.2, or a side shield (not shown). Each spintronic device300,325,350,375may individually be a part of the disk drive100ofFIG.1, or a part of the read/write head200ofFIG.2. Each spintronic device300,325,350,375may be referred to herein as a spin torque oscillator (STO) or STO stack.

As discussed above, an STL can be used to enhance a write field by opposing the gap field, but a single STL in the gap has scaling limitations. To address such scalability issues, various embodiments disclosed here propose using two STLs in the gap to oppose the gap field. In some embodiments, one STL is driven by a main pole notch and another STL is driven by a trailing shield notch. In some embodiments, one of the notches comprises a negative beta material such as FeCr. In some embodiments, the two STLs are separated by one or more spin kill layers so no torque is transferred between the two STLs. Some embodiments further include one or more layers of negative beta material placed between the two STLs to further reduce the interaction between them.

The spintronic device300ofFIG.3Acomprises a main pole (MP) notch304disposed on the main pole302, a first spacer layer306disposed on the MP notch304, a first spin torque layer (STL1)308disposed on the first spacer layer306, a spin kill (SK) layer310disposed on the STL1308, a second STL (STL2)312disposed on the SK layer310, a second spacer layer314disposed on the STL2312, a trailing shield (TS) notch316disposed on the second spacer layer314, and a hot seed (HS) layer318disposed on the TS notch316adjacent to the trailing shield (not shown). In one embodiment, which can be combined with other embodiments, the STL1308and/or the STL2312are spin polarization layers (SPL) or spin polarizing layers. InFIGS.3A-3D, the arrows toward the main pole (negative Y direction) in STLs308and312indicate the STLs being switched to oppose the gap field (Hgap) which is in the direction from the main pole to the trailing shield (positive Y direction).

The spintronic device325ofFIG.3Bis the same as the spintronic device300ofFIG.3A; however, the spintronic device325further comprises a first negative beta material (NBM) layer320disposed between the STL1308and the SK layer310.

The spintronic device350ofFIG.3Cis the same as the spintronic device300ofFIG.3A; however, the spintronic device350further comprises a second NBM layer322disposed between the STL2312and the SK layer310.

The spintronic device375ofFIG.3Dis the same as the spintronic device325ofFIG.3Band/or the spintronic device350ofFIG.3C; however, the spintronic device375further comprises both the first NBM layer320disposed between the STL1308and the SK layer310, and the second NBM layer322disposed between the STL2312and the SK layer310such that the SK layer310is sandwiched between the first NBM layer320and the second NBM layer322.

As noted above, each spintronic device300,325,350,375may be disposed between the main pole and a shield, such as the trailing shield, leading shield, or side shield. Thus, while the TS notch316is referred to herein as a “trailing shield” notch, the TS notch316may be a leading shield notch or a side shield notch. Similarly, while the HS layer318is referred to herein as being disposed adjacent to a trailing shield, the HS layer318may be disposed adjacent to a leading shield or a side shield.

In each spintronic device300,325,350, and375, the first spacer layer306and the second spacer layer314each individually comprises a long spin-diffusion length material such as Cu, Ag, or Cu and Ag alloys, or combinations thereof, and has a thickness in the y-direction of about 2 nm to about 5 nm, such as about 3 nm. The STL1308and the STL2312each individually comprises NiFe, CoFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, and/or other soft or hard ferromagnetic materials, other Heusler alloys, other suitable magnetic layers, and/or multiple layers thereof. The STL1308and the STL2312each individually has a thickness in the y-direction of about 2 nm to about 5 nm, such as about 3 nm. The SK layer310may comprise a non-magnetic material having a high resistivity, such as Cr, and have a thickness in the y-direction of about 2 nm to about 5 nm, such as about 3 nm. As noted above, each spintronic device300,325,350, and375is disposed in a gap, which may have a total width or thickness in the y-direction of about 20 nm. Thus, each spintronic device300,325,350, and375may have a total thickness in the y-direction from the first spacer layer306to the second spacer layer312of less than about 20 nm.

In each spintronic device300,325,350,375, the MP notch304drives the STL1308while the TS notch316drives the STL2312. Polarized electrons from the STL1308are reflected off from a first interface between the MP notch304and the first spacer layer306, back toward the STL1308. Spin accumulation and spin torque occurs at a second interface between the first spacer layer306and the STL1308. Similarly, polarized electrons from the STL2312are reflected off from a first interface between the TS notch316and the second spacer layer314, back toward the STL1312. Spin accumulation and spin torque occurs at a second interface between the second spacer layer314and the STL2312. The SK layer310is disposed between and in contact with the STL1308and the STL2312to prevent spin torque from being transferred in between the STL1308and the STL2312.

In the spintronic devices325,350, and375, the first and second NBM layers320,322each individually comprises one or more of Fe, Cr, N, Co, and/or Gd, such as FeCr, or an iron nitride (FexNx), and has a thickness in the y-direction of about 0.5 nm to about 1 nm. The first and/or second NBM layers320,322provide negative polarization at the interface(s) between the SK layer310and the STL1308and/or STL2312. The negative polarization introduced by the first and/or second NBM layers320,322enhances performance of the spintronic devices325,350, and375, even if cross-talk occurs during operation. As such, the first and/or second NBM layers320,322further eliminate or reduce any spin torque between the STL1308and the STL2312that may be generated when the current is applied.

When current is applied to flow electrons from the MP302through a spintronic device300,325,350,375to the hot seed layer318in the direction shown by the arrow330(i.e., in the y-direction), such as by the current source270ofFIG.2, each spintronic device300,325,350,375is referred to as having a forward stack configuration. In such a forward stack, the MP notch304comprises a negative beta material having a Bs of about 1.6 T, for example, one or more of Fe, Cr, N, Co, and/or Gd, such as FeCr, or an iron nitride (FexNx, where x is a numeral), and the TS notch316comprises CoFe having a Bs of about 2.4 T. The MP notch304and the TS notch316each individually has a thickness in the y-direction of about 2 nm to about 8 nm, such as about 5 nm. In some embodiments, the STL1308and the STL2312have a same thickness in the y-direction and a same magnetic moment. In other embodiments, the STL1308may be thinner than the STL2312and have a smaller magnetic moment, as the STI1308is driven by the MP notch304comprising the negative beta material in the forward stack. In one embodiment where the MP notch304comprises a negative beta material, the TS notch316may be absent, and in such an embodiment, the STL2312would be driven by the trailing shield.

When current is applied to flow electrons from the hot seed layer318through a spintronic device300,325,350,375to the MP302in the direction shown by the arrow332(i.e., in the −y-direction), such as by the current source270ofFIG.2, each spintronic device300,325,350,375is referred to as having a reverse stack configuration. In such a reverse stack, the MP notch304comprises CoFe having a Bs of about 2.4 T, and the TS notch316comprises a negative beta material having a Bs of about 1.6 T, for example, one or more of Fe, Cr, N, Co, and/or Gd, such as FeCr, or an iron nitride (FexNx, where x is a numeral). The MP notch304and the TS notch316each individually has a thickness in the y-direction of about 2 nm to about 8 nm, such as about 5 nm. In other words, the material of each of the MP notch304and the TS notch316is dependent, at least in part, on the direction of the applied current. In some embodiments, the STL1308and the STL2312have a same thickness in the y-direction and a same magnetic moment. In other embodiments, the STL2312may be thinner than the STL1308and have a smaller magnetic moment, as the STL2312is driven by the TS notch316comprising the negative beta material in the reverse stack. In one embodiment where the TS notch316comprises a negative beta material, the MP notch304may be absent, and in such an embodiment, the STL1308would be driven by the main pole.

FIG.4Ashows a graph400illustrating the effective magnetic field (Neff) in Oe vs a down-track location in nm for a forward stack spintronic device, according to one embodiment.FIG.4Bshows a graph450illustrating the effective magnetic field (Neff) in Oe vs a down-track location in nm for a reverse stack spintronic device, according to another embodiment. The forward stack spintronic device modeled in the graph400may be any of the spintronic devices300,325,350,375ofFIGS.3A-3Dwhen: (1) the MP notch304comprises the negative beta material; and (2) current is applied to flow electrons from the MP302through a spintronic device300,325,350,375to the hot seed layer318in the direction shown by the arrow330. The reverse stack spintronic device modeled in the graph450may be any of the spintronic devices300,325,350,375ofFIGS.3A-3Dwhen: (1) the TS notch316comprises the negative beta material; and (2) current is applied to flow electrons from the hot seed layer318through a spintronic device300,325,350,375to the MP302in the direction shown by the arrow332.

In the graph400, line430represents the STL2312only being on or active (i.e., being driven by a current), line432represents the STL1308only being on or active, line434represents both the STL1308and the STL2312being on or active, and line436represents the MP notch304comprising the negative beta material in a spintronic device that does not comprise a STL. As shown in the graph400by line434, both the STL1308and the STL2312being on or active results in a higher magnetic field and a higher gradient with no spin torque being transferred between the STL1308and the STL2312.

In the graph450, line454represents both the STL1308and the STL2312being on or active, and line456represents the TS notch316comprising the negative beta material. As shown in the graph400by line454, both the STL1308and the STL2312being on or active results in a higher magnetic field and a higher gradient with no spin torque being transferred between the STL1308and the STL2312.

Utilizing two STLs in a spintronic device produces a stronger magnetic field and gradient, facilitates simple and effective magnetic recording performance and reliability, and increases areal density capability (ADC) for magnetic recording. The SK layer and the optional thin, negative beta material layers disposed between the two STLs prevent spin torque from being transferred between the two STLs, ensuring performance of the spintronic device does not degrade while still achieving a higher magnetic field and a higher gradient.

In one embodiment, a magnetic recording head comprises a main pole, a shield, and a spintronic device disposed between the main pole and the shield, the spintronic device comprising: a main pole notch disposed on the main pole, a first spin torque layer (STL) disposed over the main pole, a spin kill layer disposed over the first STL, a second STL disposed over the spin kill layer, and a shield notch disposed over the second STL.

The spintronic device further comprises one or more negative beta material (NBM) layers disposed in contact with the spin kill layer. Each of the one or more NBM layers comprises FeCr and has a thickness of about 0.5 nm to about 1 nm. The spintronic device further comprises: a first spacer layer disposed between the main pole notch and the first STL, a second spacer layer disposed between the second STL and the shield notch, and a hot seed layer disposed between the shield notch and the shield. The spintronic device has a total thickness less than or equal to about 20 nm. A magnetic recording device comprises the magnetic recording head and a current source coupled to the magnetic recording head. The current source is configured to flow electrons from the main pole through the spintronic device to the shield, and wherein the main pole notch comprises FeCr and the shield notch comprises CoFe. The current source is configured to flow electrons from the shield through the spintronic device to the main pole, and wherein the main pole notch comprises CoFe and the shield notch comprises FeCr.

In another embodiment, a magnetic recording head comprises a main pole, a main pole notch disposed on the main pole, a first spacer layer disposed on the main pole notch, a first STL disposed on the first spacer layer, a spin kill layer disposed over the first STL, a second STL disposed over the spin kill layer, a second spacer layer disposed on the second STL, a shield notch disposed on the second spacer layer, a hot seed layer disposed on the shield notch, and a shield disposed on the hot seed layer.

The main pole notch comprises FeCr and the shield notch comprises CoFe. The second STL is thicker than the first STL, and the second STL has a higher magnetic moment than the first STL. The main pole notch comprises CoFe and the shield notch comprises FeCr. The first STL is thicker than the second STL, and the first STL has a higher magnetic moment than the second STL. The magnetic recording head further comprises one or more negative beta material (NBM) layers disposed in contact with the spin kill layer, wherein each of the one or more NBM layers comprises FeCr and has a thickness of about 0.5 nm to about 1 nm. A magnetic recording device comprises the magnetic recording head and a current source coupled to the magnetic recording head.

In yet another embodiment, a magnetic recording head comprises a main pole, a main pole notch disposed on the main pole, a first STL disposed over the main pole notch, a second STL disposed over the first STL, means for preventing spin torque from being transferred between the first STL and the second STL, a shield notch disposed over the second STL, a hot seed layer disposed on the shield notch, and a shield disposed on the hot seed layer.

The main pole notch comprises FeCr and the shield notch comprises CoFe, and wherein the second STL is thicker than the first STL. The main pole notch comprises CoFe and the shield notch comprises FeCr, and wherein the first STL is thicker than the second STL. The first STL and the second STL have a same thickness. The magnetic recording head further comprises: a first spacer layer disposed between the main pole notch and the first STL, a second spacer layer disposed between the second STL and the shield notch, and one or more negative beta material (NBM) layers disposed in contact with either the first STL or the second STL, wherein each of the one or more NBM layers comprises FeCr and has a thickness of about 0.5 nm to about 1 nm. A collective thickness of the first STL, the second STL, the first spacer layer, the second spacer layer, the one or more NBM layers, and the means for preventing spin torque from being transferred between the first STL and the second STL is less than about 20 nm. A magnetic recording device comprises the magnetic recording head and a current source coupled to the magnetic recording head.

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.