Patent ID: 12205620

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).

The present disclosure generally relates to a magnetic recording system comprising a magnetic recording head. The magnetic recording head comprises a main pole, a shield, and a spintronic device disposed between the main pole and the shield. The spintronic device comprises a field generation layer (FGL) spaced a distance of about 2 nm to about 3 nm from the main pole, a first spacer layer disposed on the FGL, a spin torque layer (STL) disposed on the first spacer layer, a second spacer layer disposed on the STL, and a negative polarization layer (NPL) disposed between the second spacer layer and the shield. The spintronic device has a length of about 17 nm to about 21. During operation, the STL has a magnetization precession of about 16 degrees to about 170 degrees, and the FGL has a magnetization precession of about 60 degrees to about 70 degrees.

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 arrow233.

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-3Billustrate exemplary conventional spintronic devices300,350.FIG.3Aillustrates a forward conventional spintronic device300, andFIG.3Billustrates a reverse conventional spintronic device350. Each spintronic device300,350is disposed in a trailing gap303disposed between a main pole302and a trailing shield304. The arrows shown within each layer of the spintronic devices300,350represent the magnetization direction of each layer. Both of these devices provide assisting recording effects via both a oscillating field generation layer for the aforementioned AC-field MAMR effect at the media to lower the media coercivity (“microwave assist” below) and a spin torque layer that is switched against a gap field to improve the write field experienced by the magnetic recording media (“DC assist” below).

In the spintronic device300, a seed layer306is disposed on the main pole (MP)302, a spin polarization layer (SPL)308is disposed on the seed layer306, a first spacer layer310is disposed on the SPL308, a field generation layer (FGL)312is disposed on the first spacer layer310, a spin scattering (SS) layer314is disposed on the FGL312, a spin torque layer (STL)316is disposed on the SS layer314, a second spacer layer318is disposed on the STL316, and a trailing shield notch320is disposed in contact with the second spacer layer318and the trailing shield304. In some embodiments, the trailing shield notch320may be considered part of the trailing shield304. During operation, when current is applied, electrons (e) flow from the main pole302, through the spintronic device300, to the trailing shield304. Similarly, the magnetic gap field (H) is directed from the main pole302, through the spintronic device300, to the trailing shield304.

The spintronic device300has a length340in the x-direction from the main pole302to the trailing shield304of about 25 nm to about 28 nm. The FGL312is spaced a distance342from the main pole302in the x-direction of about 10 nm. Because the FGL312is disposed towards the center of the spintronic device300, the FGL312is less effective. As such, the location of the FGL312is not optimal.

In the spintronic device350, a main pole notch322is disposed on the main pole302, the second spacer layer318is disposed on the main pole notch322, the STL316is disposed on the second spacer layer318, the SS layer314is disposed on the STL316, the FGL312is disposed on the SS layer314, the first spacer layer310is disposed on the FGL312, the SPL308is disposed on the first spacer layer310, and a cap layer305is disposed in contact with the SPL308and the trailing shield304. In some embodiments, the main pole notch322may be considered part of the main pole302. During operation, when current is applied, electrons (e) flow from the trailing shield304, through the spintronic device350, to the main pole302. The magnetic gap field (H) is directed from the main pole302, through the spintronic device300, to the trailing shield304.

The spintronic device350has a length344in the x-direction from the main pole302to the trailing shield304of about 25 nm to about 28 nm. The FGL312is spaced a distance346from the main pole302in the x-direction of about 10 nm. Because the FGL312is disposed towards the center of the spintronic device350, the FGL312is less effective. As such, the location of the FGL312is unfavorable.

In both spintronic devices300and350, the seed layer306and the cap layer305may each individually comprise a non-magnetic material, such as Cr, Ru, NiFeTa, and/or NiAl, and have a thickness in the x-direction of about 2 nm to about 6 nm. The first spacer layer310and the second spacer layer318may each individually comprise a non-magnetic layer, such as Cu, and have a thickness in the x-direction of about 2 nm to about 3 nm. The SS layer314comprises Cr and has a thickness in the x-direction of about 3 nm to about 5 nm. The SPL308comprises a magnetic material, such as CMG, NiFe, and/or CoFe, and has a thickness in the x-direction of about 1 nm to about 2 nm. The FGL312comprises a magnetic material, such as CoFe and/or a Co/Fe multilayer, and has a thickness in the x-direction of about 5 nm to about 10 nm. The STL316comprises a magnetic material, such as CMG and/or NiFe, and has a thickness in the x-direction of about 3 nm to about 6 nm. The trailing shield notch320comprises a magnetic material, such as CoFeNi or other suitable magnetic materials, and has a thickness in the x-direction of about 2 nm to about 10 nm.

Each spintronic device300and350comprises three magnetic layers, the FGL312and the SPL308for microwave assist, and the STL316from direct current (DC) assist. As such, the lengths340,344of each spintronic device300,350is larger than desired in order to accommodate the three magnetic layers312,308,316. Furthermore, torque from the FGL312degrades the STL316, and vice versa. To help prevent torque from degrading the FGL312and/or the STL316, the SS layer314is required to be disposed between the FGL312and the STL316.

FIGS.4A-4Dillustrate cross-sectional view of spintronic devices400,425,450,475, according to various embodiments. Each spintronic device400,425,450, and475may independently be the spintronic device230ofFIG.2, and each spintronic device400,425,450, and475is disposed in a gap403between a main pole402, such as the main pole220ofFIG.2, and a shield404, such as the trailing shield240ofFIG.2, a leading shield206ofFIG.2, or a side shield (not shown). Each spintronic device400,425,450,475may individually be a part of the disk drive100ofFIG.1, or a part of the read/write head200ofFIG.2. Each spintronic device400,425,450,475may be referred to herein as a spin torque oscillator (STO) or STO stack. It is noted as the trailing shield is used as an example to illustrate the various embodiments, and the spintronic device can be between the main pole and other shields in the recording head, such as leading shield and side shields.

The spintronic devices400and425ofFIGS.4A-4Bare forward stack configurations, and the spintronic devices450,475ofFIGS.4C-4Dare reverse stack configurations. The arrows shown within each layer of the spintronic devices400,425,450,475represent the magnetization direction of the layer.

The spintronic device400ofFIG.4Acomprises an optional first notch422disposed on the main pole402, a first spacer layer426disposed on the optional first notch422or on the main pole402, a FGL412disposed on the first spacer layer426, a second spacer layer428disposed on the FGL412, a STL416disposed on the second spacer layer428, a third spacer layer430disposed on the STL416, a negative polarization layer (NPL)424disposed on the third spacer layer430, and a second notch420disposed in contact with the NPL424and the shield404. In some embodiments, the first notch422is considered a part of the main pole402, and the second notch420is considered a part of the shield404.

The first spacer layer426, the second spacer layer428, and the third spacer layer430may each individually comprise a non-magnetic layer, such as Cu, Ru, or a combination of Cu, Ru, and/or Cr. The first spacer layer426and the second spacer layer428each has a thickness in the x-direction of about 2 nm to about 5 nm. The third spacer layer430has a thickness in the x-direction of about 2 nm to about 5 nm. The FGL412comprises a magnetic material, such as CoFe and/or a Co/Fe multilayer, and has a thickness in the x-direction of about 5 nm to about 10 nm. The STL416comprises a magnetic material, such as CMG and/or NiFe, and has a thickness in the x-direction of about 4 nm to about 6 nm. The NPL424comprises a material having a negative polarization, such as FeCr, and has a thickness in the x-direction of about 5 nm. The second notch420comprises a magnetic material, such as CoFeNi or other suitable magnetic materials, and has a thickness in the x-direction of about 2 nm to about 5 nm. The first notch422comprises a high moment magnetic material, such as CoFe, and has a thickness in the x-direction of about 2 nm to about 5 nm.

The spintronic device425ofFIG.4Bis the same as the spintronic device400ofFIG.4A; however, the third spacer layer430comprises a first sublayer432adisposed in contact with the STL416and a second sublayer432bdisposed in contact with the NPL424. The first sublayer432amay comprise Cu and have a thickness in the x-direction of about 1 nm to about 3 nm. The second sublayer432bmay comprise Cr and/or Ru and have a thickness in the x-direction of about 1 nm to about 3 nm. Thus, the third spacer layer430has a total thickness in the x-direction of about 2 nm to about 6 nm.

Each spintronic device400,425individually has a length440in the x-direction from the main pole402to the shield404of about 17 nm to about 21 nm. The FGL412of each spintronic device400,425is spaced a distance442from the main pole402in the x-direction of about 2 nm to about 3 nm. In each spintronic device400,425, during operation when current is applied, electrons flow from the shield404, through either spintronic device400or425, to the main pole402. The magnetic gap field (H) is directed from the main pole402, through either spintronic device400or425, to the shield404.

Comparing the spintronic devices400,425, to the conventional spintronic devices300,350ofFIGS.3A-3B, the FGL412of each spintronic device400,425is spaced about 7 nm to about 8 nm closer to the main pole402than the FGL312of either spintronic device300,350is spaced to the main pole302. As such, the FGL412is in a more favorable location than the FGL312, and thus, the FGL412is more effective than the FGL312, as the FGL312being near the center of the spintronic device300or350can degrade the gradient. By having the FGL412closer to the main pole402, the AC field generated is closer to a trailing edge of the main pole402, which is more effective for a MAMR effect gain. Similarly, the STL416is disposed closer to a center of the gap403, which is an optimal location for the STL416, as the STL416provides a DC assist, providing a dynamic DC field compensation, and further applies torque to the FGL412.

The spintronic device450ofFIG.4Cis similar to the spintronic device400ofFIG.4A; however, the positioning of the various layers are different. In the spintronic device450, the NPL424is disposed on the second notch420or the main pole402, the third spacer layer430is disposed on the NPL424, the STL416is disposed on the third spacer layer430, the second spacer layer428is disposed on the STL416, the FGL412is disposed on the second spacer layer428, the first spacer layer426is disposed on the FGL412, and the first spacer layer426is disposed in contact with the FGL412and the first notch422.

The spintronic device475ofFIG.4Dis the same as the spintronic device450ofFIG.4C; however, however, the third spacer layer430comprises the first sublayer432adisposed in contact with the STL416and the second sublayer432bdisposed in contact with the NPL424, similar to the spintronic device425ofFIG.4B.

Each spintronic device450,475individually has a length444in the x-direction from the main pole402to the shield404of about 17 nm to about 21 nm. The FGL412of each spintronic device450,475is spaced a distance446from the shield404in the x-direction of about 2 nm to about 3 nm. In each spintronic device450,475, during operation when current is applied, electrons from the main pole402, through either spintronic device450or475, to the shield404. The magnetic gap field (H) is directed from the main pole402, through either spintronic device450or475, to the shield404.

In each spintronic device400,425,450,475, the FGL412provides alternating current (AC) magnetic field assist while the STL416provides DC assist. Rather than comprising three magnetic layers like conventional spintronic devices as shown inFIGS.3A-3B, each spintronic device400,425,450,475comprises only two magnetic layers, the FGL412and the STL416. As compared to the STL inFIGS.3A-3B, the STL416, aided by the NPL424, now has a dynamic nature that serves the functions of both generating the AC field and providing a DC field assist. In other words, the STL416precessing switches against the gap field and provides torque to the FGL412, eliminating the need for the third magnetic layer.

During operation of each spintronic device400,425,450,475, the STL416's magnetization is reversed by torques from the FGL412and the NPL424. The FGL412has a magnetization precession at an angle of about 60 degrees to about 70 degrees (with a 0 degree reference in the positive x-direction). Thus, STL416of each spintronic device400,425,450,475has a magnetization precession at an angle of about 160 degrees to about 170 degrees. The STL416having a higher magnetization precession angle increases the effective moment in the gap field direction (Bst; where the Bst is a product of saturation magnetization and the thickness of the STL416or the permeability of free space) in the gap field direction, which in turn improves the overall performance, as a larger Bst provides a larger DC field assist by the STL416.

Comparing the spintronic devices400,425,450,475to the conventional spintronic devices300,350ofFIGS.3A-3B, the spintronic devices400,425,450,475do not comprise a SS layer or a SPL. As such, the spintronic devices400,425,450,475each has a total length444at least 5 nm to about 8 nm less than the lengths340,344of the spintronic devices300,350.

FIG.5is a graph500illustrating the magnetization direction angles of the STL416and the FGL412of any of the spintronic devices400-475ofFIGS.4A-4D, according to one embodiment. The graph500shows the angle in degrees versus time in ns (i.e., the amount of time current flowed through the spintronic devices400-475).

The graph500shows that the STL416having a Bst of about 5.2 T*nm can operate at an average angle of about 170 degrees, where the generated field strength is proportional to the Bst times cosine (170). The STL416is able to achieve the 170 degree angle due, at least in part, to assistance from the NPL424. The FGL412can operate an average angle of about 62 degrees at a frequency of about 28 GHZ. Furthermore, as shown in the graph, the STL416and the FGL412are able to maintain their respective angles over time without distorting. The angles of the STL416and the FGL412further increase a combined effective magnetic field of the main pole402and the spintronic devices400-475ofFIGS.4A-4Dby about 400 Oe and the total field gradient by about 100 Oe/nm.

Therefore, spintronic devices comprising a FGL disposed near the main pole, a STL disposed near the center of the gap, and a negative polarization layer disposed near the shield having a reduced length in the gap, in turn decreasing the size of the gap between the main pole and the shield. Moreover, such spintronic devices are able to increase the magnetization precession angle of the STL, achieving a larger Bst, where the Bst is a product of saturation magnetization and the thickness of the STL or the permeability of free space, in the gap field direction, which results in the overall performance of each spintronic device being improved.

In one embodiment, a magnetic recording head comprises a main pole, a shield, and a spintronic device is disposed between a main pole and a shield, the spintronic device comprising a field generation layer (FGL) spaced a distance of about 2 nm to about 3 nm from the main pole, a first spacer layer disposed in contact with the FGL, a spin torque layer (STL) disposed in contact with the first spacer layer, and a negative polarization layer (NPL) disposed between the STL and the shield, the NPL comprising a negative polarization material.

The spintronic device has a length of about 17 nm to about 21 nm. The spintronic device further comprises a second spacer layer disposed between and in contact with the STL and the NPL. The second spacer layer comprises a first sublayer disposed in contact with the STL and a second sublayer disposed in contact with the NPL. The spintronic device further comprises a first notch disposed on the main pole, a third spacer layer disposed in contact with the first notch and the FGL, and a second notch disposed between and in contact with the NPL and the shield. The NPL comprises FeCr, and wherein the first notch comprises CoFe. A magnetic recording head comprises the spintronic device. A magnetic recording system comprises the magnetic recording head. During operation, a current is configured to flow electrons from the shield through the spintronic device to the main pole, and the STL is configured to apply torque to the FGL and to provide a direct current assist to enhance a recording field during operation.

In another embodiment, a magnetic recording head comprises a main pole, a shield disposed adjacent to the main pole, and a spintronic device disposed between the main pole and the shield, the spintronic device comprising: a first spacer layer disposed adjacent to the main pole, a field generation layer (FGL) disposed on the first spacer layer, a second spacer layer disposed on the FGL, a spin torque layer (STL) disposed on the second spacer layer, a third spacer layer disposed on the STL, and a negative polarization layer (NPL) disposed between the third spacer layer and the shield, the NPL comprising FeCr, wherein the spintronic device has a length of about 17 nm to about 21 nm.

The magnetic recording head further comprises a first notch disposed between and in contact with the main pole and the first spacer layer, the first notch comprising a high moment magnetic material, and a second notch disposed between and in contact with the NPL and the shield, the second notch comprising a magnetic material. The third spacer layer comprises Cu, Ru, or a combination of one or more of Cu, Ru, and Cr. The third spacer layer comprises a first sublayer and a second sublayer. The first spacer layer has a thickness of about 2 nm to about 3 nm. A magnetic recording system comprises the magnetic recording head. The magnetic recording system is configured to apply a current to the magnetic recording head such that electrons flow from the shield, through the spintronic device, to the main pole. The STL is configured to apply torque to the FGL and to provide a direct current assist to enhance a recording field during operation

In yet another embodiment, a magnetic recording head comprises a main pole, a shield disposed adjacent to the main pole, and a spintronic device disposed between the main pole and the shield, the spintronic device comprising: a first notch disposed on the main pole, a negative polarization layer (NPL) disposed on the first notch, the NPL comprising FeCr, a first spacer layer disposed on the NPL, a spin torque layer (STL) disposed on the first spacer layer, a second spacer layer disposed on the STL, a field generation layer (FGL) disposed on the second spacer layer, a third spacer layer disposed on the FGL, and a second notch disposed between and in contact with the third spacer layer and the shield.

The first spacer layer comprises a first sublayer and a second sublayer, the first and second sublayer each individually comprising Cu, Ru, or a combination of one or more of Cu, Ru, and Cr. The spintronic device has a length of about 17 nm to about 21 nm, and wherein the third spacer layer has a thickness of about 2 nm to about 3 nm. The first notch comprises a magnetic material and the second notch comprises CoFe. A magnetic recording system comprises the magnetic recording head. The magnetic recording system is configured to apply a current to the magnetic recording head such that electrons flow from the main pole, through the spintronic device, to the shield.

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.