Patent Description:
In spin electronic devices or spintronic devices, such as sensors utilized in magnetic recording heads, both spin polarization and anisotropic field play important roles. For example, such spintronic devices may be used in spin-orbit torque (SOT) magnetic tunnel junction (MTJ) applications, such as for a spin Hall layer for energy-assisted magnetic recording write heads and magnetoresistive random access memory (MRAM) devices. Materials utilized in these spintronic devices typically have (<NUM>) a positive spin polarization with no anisotropic field, such as CoFe, Co, Ni, and CoMnGe, (<NUM>) a positive spin polarization and a negative anisotropic field, such as CoFe multilayer structures, (<NUM>) a negative spin polarization with no anisotropic field, such as FeCr, FeV, and FeN, or (<NUM>) both a positive spin polarization and a positive anisotropic field, such as CoNi, CoPt, CoPd, and Mn<NUM>Ga. Because there are no materials reported to have a negative spin polarization with a negative anisotropic field, the spintronic devices generally have less freedom and are more restricted.

Therefore, there is a need in the art for a material having both a negative spin polarization and a negative anisotropic field for use in spintronic devices.

<NPL>" describes Co<NUM>/Cr<NUM>-x/Fex/Al full Heusler alloy thin films that have been epitaxially grown on GaAs(<NUM>) substrates under the optimized condition. Structural analysis reveals the detailed growth mechanism of the films and confirms that the films form the perfectly ordered L2/sub <NUM>/ structure. A magnetization measurement also shows the films possess very strong uniaxial crystalline anisotropy due to the epitaxial growth. By using these films as bottom electrodes of magnetic tunnel junctions, the maximum tunnel magnetoresistance ratio of <NUM>% is observed after post-annealing with AI-O insulating barriers for x=<NUM>.

<NPL>", describes an investigation of magnetization reversal and the magnetic anisotropy of epitaxial Co(<NUM>) and Fe(<NUM>) films and a comparison with epitaxial Co(<NUM>)/Cr(<NUM>)/Fe(<NUM>) trilayers with spin valve characteristics.

<CIT> concerns static memories applying multiple magnetic layers, in particular a tunneling magneto-resistance (TMR) multilayer film material. The TMR multilayer film material is of a high-spin polarizability interface (CoTiSb)x/Fey/(CoTiSb)z superlattice structure, wherein the x, the y and the z refer to the atom layer number of each component, the superlattice structure is a multilayer film structure which grows coherently along the direction of a semi-Heusler structure CoTiSb single crystal [<NUM>] by taking a three-layer film as a basic unit and is capable of achieving periodic epitaxy by taking the basic unit as a base, and in an inserted Fe layer and a high-spin polarization layer induced by the same, a few vacancy or island-shaped defects cannot have a great influence on high-spin polarizability. The tunneling magneto-resistance multilayer film material overcomes the defect that unmatching of multilayer film interfaces of a TMR material in practical use and unmatching of electronic structures of different interlayer materials can have adverse influences on practical spin polarizability and magneto-resistance in the prior art.

The invention is a spintronic device, magnetic media drive, magnetoresistive random access memory device, magnetic sensor, and magnetic recording head as defined in the appended claims.

Aspects of the present disclosure generally relate to a spintronic device for use in a magnetic media drive, a magnetoresistive random access memory device, a magnetic sensor, or a magnetic recording write head. The spintronic device comprises a multilayer structure having a negative spin polarization and a negative anisotropic field. The multilayer structure comprises a plurality of layers, each layer of the plurality of layers comprising a first sublayer comprising Fe and a second sublayer comprising Co. At least one of the first sublayer and the second sublayer comprises one or more of Cr and V. The first and second sublayers are alternating. The negative anisotropic field of the multilayer structure is between about - <NUM> T to about -<NUM> T, and an effective magnetization of the multilayer structure is between about <NUM> T to about <NUM> T.

In one embodiment, a spintronic device comprises a multilayer structure having a negative spin polarization and a negative anisotropic field, the multilayer structure comprising a plurality of layers, each layer of the plurality of layers comprising a first sublayer comprising Fe and a second sublayer comprising Co, wherein at least one of the first sublayer and the second sublayer further comprise one or more of Cr and V. The first and second sublayers are alternating.

In another embodiment, a spintronic device comprises a substrate and a multilayer structure having a negative spin polarization and a negative anisotropic field disposed over the substrate, the multilayer structure comprising a plurality of alternating first layers and second layers. Each of the first layers comprises Fe and one or more of Cr and V, and each of the second layers comprises Co. Each of the first layers has a first thickness greater than or equal to a second thickness of each of the second layers. The spintronic device further comprises a cap layer disposed over the multilayer structure.

In yet another embodiment, a spintronic device comprises a multilayer structure having a negative spin polarization and a negative anisotropic field, the multilayer structure comprising a plurality of alternating first layers and second layers. Each of the first layers comprises at least one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, and FeCrxVyTiz, where each of x, y, and z is a positive number, and x,y, z are atomic percentages, and each of the second layers comprising Co. Each of the first layers has a first thickness between about <NUM> to about <NUM> and each of the second layers has a second thickness between about <NUM> to about <NUM>. The spintronic device further comprises one or more layers disposed over the multilayer structure.

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).

Aspects of the present disclosure generally relate to a spintronic device for use in a magnetic media drive, a magnetoresistive random access memory device, a magnetic sensor, or a magnetic recording write head. The spintronic device comprises a multilayer structure having a negative spin polarization and a negative anisotropic field. The multilayer structure comprises a plurality of layers, each layer of the plurality of layers comprising a first sublayer comprising Fe and a second sublayer comprising Co. At least one of the first sublayer and the second sublayer comprises one or more of Cr, and V. The first and second sublayers are alternating. The negative anisotropic field of the multilayer structure is between about -<NUM> T to about -<NUM> T, and an effective magnetization of the multilayer structure is between about <NUM> T to about <NUM> T.

It is to be understood that the embodiments discussed herein are applicable to a data storage device such as a hard disk drive (HDD) as well as a tape drive such as a tape embedded drive (TED) or an insertable tape media drive such as those made according to Linear Tape Open (LTO) standards. An example TED is described in copending patent application titled "Tape Embedded Drive," <CIT>, assigned to the same assignee of this application. As such, any reference in the detailed description to an HDD or tape drive is merely for exemplification purposes and is not intended to limit the disclosure unless explicitly claimed. For example, references to disk media in an HDD embodiment are provided as examples only, and can be substituted with tape media in a tape drive embodiment. Furthermore, reference to or claims directed to magnetic recording devices or data storage devices are intended to include at least both HDD and tape drive unless HDD or tape drive devices are explicitly claimed.

It is also to be understood that aspects disclosed herein, such as the magnetoresistive devices, may be used in magnetic sensor applications outside of HDD's and tape media drives such as TED's, such as spintronic devices other than HDD's and tape media drives. As an example, aspects disclosed herein may be used in magnetic elements in magnetoresistive random-access memory (MRAM) devices (e.g., magnetic tunnel junctions as part of memory elements), magnetic sensors or other spintronic devices.

<FIG> illustrates a magnetic recording device <NUM> embodying this disclosure. As shown, at least one rotatable magnetic media <NUM> is supported on a spindle <NUM> and rotated by a disk drive motor <NUM>. The magnetic recording on each disk is in the form of any suitable patterns of data tracks, such as annular patterns of concentric data tracks (not shown) on the magnetic media <NUM>.

At least one slider <NUM> is positioned near the magnetic media <NUM>, each slider <NUM> supporting one or more magnetic head assemblies <NUM>. As the magnetic media rotates, the slider <NUM> moves radially in and out over the media surface <NUM> so that the magnetic head assembly <NUM> may access different tracks of the magnetic media <NUM> where desired data are written. Each slider <NUM> is attached to an actuator arm <NUM> by way of a suspension <NUM>. The suspension <NUM> provides a slight spring force that biases the slider <NUM> toward the media surface <NUM>. Each actuator arm <NUM> is attached to an actuator means <NUM>. The actuator means <NUM> as shown in <FIG> 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 <NUM>.

During operation of the magnetic recording device <NUM>, the rotation of the magnetic media <NUM> generates an air bearing between the slider <NUM> and the media surface <NUM> that exerts an upward force or lift on the slider <NUM>. The air bearing thus counter-balances the slight spring force of suspension <NUM> and supports slider <NUM> off and slightly above the media <NUM> surface by a small, substantially constant spacing during normal operation. In the case of EAMR, a DC magnetic field generated from an assist element of the magnetic head assembly <NUM> enhances the write-ability so that the write element of the magnetic head assembly <NUM> may efficiently magnetize the data bits in the media <NUM>.

The various components of the magnetic recording device <NUM> are controlled in operation by control signals generated by control unit <NUM>, such as access control signals and internal clock signals. Typically, the control unit <NUM> comprises logic control circuits, storage means, and a microprocessor. The control unit <NUM> generates control signals to control various system operations, such as drive motor control signals on line <NUM> and head position and seek control signals on line <NUM>. The control signals on line <NUM> provide the desired current profiles to optimally move and position slider <NUM> to the desired data track on media <NUM>. Write and read signals are communicated to and from write and read heads on the assembly <NUM> by way of recording channel <NUM>.

The above description of a typical magnetic disk storage system and the accompanying illustration of <FIG> are for representation purposes only. It should be apparent that disk storage systems may contain a large number of disks and actuators, and each actuator may support a number of sliders.

<FIG> is a schematic illustration of a cross sectional side view of a head assembly <NUM> facing the rotatable magnetic disk <NUM> shown in <FIG> or other magnetic storage medium, according to one implementation. The head assembly <NUM> may correspond to the head assembly <NUM> described in <FIG>. The head assembly <NUM> includes a media facing surface (MFS) <NUM>, such as an air bearing surface (ABS), facing the rotatable magnetic disk <NUM>. As shown in <FIG>, the rotatable magnetic disk <NUM> relatively moves in the direction indicated by the arrow <NUM> and the head assembly <NUM> relatively moves in the direction indicated by the arrow <NUM>.

In one embodiment, which can be combined with other embodiments, the head assembly <NUM> includes a magnetic read head <NUM>. The magnetic read head <NUM> may include a sensing element <NUM> disposed between shields S1 and S2. The sensing element <NUM> is 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 disk <NUM>, such as perpendicular recorded bits or longitudinal recorded bits, are detectable by the sensing element <NUM> as the recorded bits.

The head assembly <NUM> includes a write head <NUM>. In one embodiment, which can be combined with other embodiments, the write head <NUM> includes a main pole <NUM>, a leading shield <NUM>, a trailing shield (TS) <NUM>, and a spintronic device <NUM> disposed between the main pole <NUM> and the TS <NUM>. The main pole <NUM> serves as a first electrode. Each of the main pole <NUM>, the spintronic device <NUM>, the leading shield <NUM>, and the trailing shield (TS) <NUM> has a front portion at the MFS.

The main pole <NUM> includes 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 pole <NUM> includes 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 pole <NUM> is formed by electrodeposition. The write head <NUM> includes a coil <NUM> around the main pole <NUM> that excites the main pole <NUM> to produce a writing magnetic field for affecting a magnetic recording medium of the rotatable magnetic disk <NUM>. The coil <NUM> may be a helical structure or one or more sets of pancake structures.

In one embodiment, which can be combined with other embodiments, the main pole <NUM> includes a trailing taper <NUM> and a leading taper <NUM>. The trailing taper <NUM> extends from a location recessed from the MFS <NUM> to the MFS <NUM>. The leading taper <NUM> extends from a location recessed from the MFS <NUM> to the MFS <NUM>. The trailing taper <NUM> and the leading taper <NUM> may have the same degree or different degree of taper with respect to a longitudinal axis <NUM> of the main pole <NUM>. In one embodiment, which can be combined with other embodiments, the main pole <NUM> does not include the trailing taper <NUM> and the leading taper <NUM>. In such an embodiment, the main pole <NUM> includes a trailing side and a leading side in which the trailing side and the leading side are substantially parallel.

The TS <NUM> includes a magnetic material, such as FeNi, or other suitable magnetic materials, serving as a second electrode and return pole for the main pole <NUM>. The leading shield <NUM> may provide electromagnetic shielding and is separated from the main pole <NUM> by a leading gap <NUM>.

In some embodiments, the spintronic device <NUM> is positioned proximate the main pole <NUM> and 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 device <NUM> from a current source <NUM> to 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 device <NUM> from a current source <NUM> to produce a high frequency alternating current (AC) field to the media.

In one embodiment, which can be combined with other embodiments, the spintronic device <NUM> is electrically coupled to the main pole <NUM> and the TS <NUM>. The main pole <NUM> and the TS <NUM> are separated in an area by an insulating layer <NUM>. The current source <NUM> may provide electron current to the spintronic device <NUM> through the main pole <NUM> and the TS <NUM>. For direct current or pulsed current, the current source <NUM> may flow electron current from the main pole <NUM> through the spintronic device <NUM> to the TS <NUM> or may flow electron current from the TS <NUM> through the spintronic device <NUM> to the main pole <NUM> depending on the orientation of the spintronic device <NUM>. In one embodiment, which can be combined with other embodiments, the spintronic device <NUM> is coupled to electrical leads providing an electron current other than from the main pole <NUM> and/or the TS <NUM>.

<FIG> illustrates a schematic of a multilayer structure <NUM> having negative spin polarization and negative anisotropic field (-Hk), according to one embodiment. For example, the multilayer structure <NUM> may be used as a free layer in a magnetic tunnel junction (MTJ) device (e.g., spin-orbit torque (SOT) MTJ devices), as a free layer in a spin-orbit torque device in an energy-assisted magnetic recording (EAMR) write head, as a free layer in a magnetoresistive random access memory (MRAM) device, as a field generating layer (FGL) in a microwave assisted magnetic recording (MAMR) write head, as a pinned layer in a magnetoresistive (MR) device, or within other spintronic devices.

As used herein, the multilayer structure <NUM> may be implemented in magnetic recording heads, including both magnetic recording write heads (e.g., as a FGL in MAMR applications) and magnetic recording read heads (e.g., as a free layer in a sensor within a read head). Furthermore, the multilayer structure <NUM> may be implemented in magnetic sensors, such as a read sensor or any other non-HDD sensing applications.

The multilayer structure <NUM> comprises a plurality of layers 302a-302n. Each layer 302a-302n comprises a first sublayer <NUM> and a second sublayer <NUM> disposed on the first sublayer <NUM> such that the first and second sublayers <NUM>, <NUM> are alternating throughout the multilayer structure <NUM>. The first sublayer <NUM> comprises iron (Fe), the second sublayer <NUM> comprises cobalt (Co), and the first sublayer <NUM> and/or the second sublayer <NUM> additionally comprises at least one of chromium (Cr) and vanadium (V).

For example, in one embodiment, the second sublayer <NUM> comprises Co, and the first sublayer <NUM> comprises FeCrx, FeVx, or FeTix, where the value of x in each is a positive number, and may be a non-integer value or an integer value. For example, the first sublayer <NUM> may comprise FeCr<NUM>, FeCr<NUM>, FeCr<NUM>, FeCr<NUM>, FeCr<NUM>, FeTi<NUM>, FeTi<NUM>, FeTi<NUM>, FeV<NUM>, FeV<NUM>, or FeV<NUM>. In some embodiments where the second sublayer <NUM> comprises Co, the first sublayer <NUM> comprises FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz, where the value of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. In some embodiments, the value of each of x, y, and/or z is between <NUM> and <NUM>.

In another embodiment, the first sublayer <NUM> comprises Fe, and the second sublayer <NUM> comprises CoCrx, CoVx, or CoTix, where the value of x in each is a positive number, and may be a non-integer value or an integer value. In some embodiments where the first sublayer <NUM> comprises Fe, the second sublayer <NUM> comprises CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz, where the value of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. In some embodiments, the value of each of x, y, and/or z is between <NUM> and <NUM>.

In yet another embodiment, both the first and second sublayers <NUM>, <NUM> comprise one or more of Cr, V, and Ti. For example, the first sublayer <NUM> comprises one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, and FeCrxVyTiz, where the value of x in each is a positive number, and may be a non-integer value or an integer value. In some embodiments, the value of each of x, y, and/or z is between <NUM> and <NUM>. The second sublayer <NUM> comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, and CoCrxVyTiz, where the value of each of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. In some embodiments, the value of each of x, y, and/or z is between <NUM> and <NUM>.

Each layer 302a-302n may collectively comprise Coa/Feb(CrxVyTiz), where a, b, x, y, and z are atomic percentages. One or more of x, y, and z may be <NUM> at%, so long as at least one of x, y, and z is a positive number greater than <NUM> at%. The atomic percent of each of Co, Fe, Cr, V, and Ti are selected based on a total number of electrons. For example, a first sublayer <NUM> comprising Fe and a second sublayer <NUM> comprising Co has a total electrons/atom of about <NUM>. As demonstrated by the Slator Pauling curve, the saturation magnetic flux density (Bs) of the layers 302a-302n decreases as the total number of electrons of each layer 302a-320n decreases by adding one or more of Cr and V.

Equation <NUM> below may be used to determine the amounts of a, b, x, y, and z in Coa/Feb(CrxVyTiz) based on a total number of electrons: <MAT>.

Thus, the doping amount of each of Cr, V, and Ti is dependent upon the total number of electrons of each layer 302a-320n. In some embodiments, the total number of electrons/atom is greater than <NUM>, like shown in Equation <NUM>.

Each first sublayer <NUM> has a first thickness <NUM> in y-direction, and each second sublayer <NUM> has a second thickness <NUM> in the y-direction. As discussed further below in <FIG>, the first thickness <NUM> and the second thickness <NUM> may be the same, or the first thickness <NUM> and the second thickness <NUM> may be different. In some embodiments, the first thickness <NUM> is greater than or equal to the second thickness <NUM>. The first thickness <NUM> may be between about <NUM> to about <NUM>. The second thickness <NUM> may be between about <NUM> to about <NUM>.

The multilayer structure <NUM> may comprise any number of layers 302a-302n until a desired total thickness <NUM> is reached. The total thickness <NUM> of the material may be about <NUM> to about <NUM>, such as about <NUM> to about <NUM>. In some embodiments, an additional first sublayer 304a is optionally included as a capping layer of the multilayer structure <NUM>. In such embodiments, the additional first sublayer 304a is in contact with the next layer of the spintronic device, such as a capping layer or a spacer layer. The additional first sublayer 304a has the first thickness <NUM>. The additional first sublayer 304a may be utilized in certain spintronic devices to control both the interface and the bulk effect. For example, FeCr has a stronger negative interface spin polarization than Co, so an additional FeCr layer may be included adjacent to a spacer layer or other subsequent layer as the first additional sublayer 304a. As such, the first additional sublayer 304a may comprise one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz, where the value of x is a positive number, and may be a non-integer value or an integer value. While the second sublayer <NUM> is shown disposed on the first sublayer <NUM>, in some embodiments, the first sublayer <NUM> is disposed on the second sublayer <NUM>. In such an embodiment, the additional first sublayer 304a may not be included.

<FIG> illustrates a schematic MFS view of a spintronic device <NUM> utilizing the multilayer structure <NUM> of <FIG>, according to one embodiment. The spintronic device <NUM> may be used as the spintronic device <NUM> or the sensing element <NUM> shown in <FIG>. For example, the spintronic device <NUM> may be a SOT MTJ device or a spin-orbit torque device. The spintronic device <NUM> may be utilized in a magnetic media drive, a magnetoresistive random access memory device, a magnetic sensor, or a magnetic recording write head. The spintronic device <NUM> is only one example or embodiment of a spintronic device that may utilize the multilayer structure <NUM>, and is not intended to be limiting.

As shown in <FIG>, the multilayer structure <NUM> is disposed over a seed layer <NUM>, a spacer <NUM> is disposed over the multilayer structure <NUM>, a pinned layer <NUM> is disposed over the spacer <NUM>, and a cap layer <NUM> is disposed over the pinned layer <NUM>. The seed layer <NUM> may comprise a NiFeTa/Ru/Cr multilayer structure. In some embodiments, the seed layer <NUM> is disposed over or in contact with a main pole (not shown), such as the main pole <NUM> of <FIG>. The spacer <NUM> may comprise Cu, NiAl, or a Ag-based material. A thin layer of Cr or V may optionally be inserted between the multilayer structure <NUM> and the spacer <NUM> to enhance the negative interfacial scattering effect. The pinned layer <NUM> may comprise CoFe. The cap layer <NUM> may comprise a Cr/Cu/Ru multilayer structure. As utilized in the spintronic device <NUM>, the multilayer structure <NUM> may comprise between five to ten layers 302a-302n, for example. The multilayer structure <NUM> may be a free layer.

<FIG> illustrates a schematic MFS view of a spintronic device <NUM> utilizing the multilayer structure <NUM> of <FIG>, according to another embodiment. The spintronic device <NUM> may be used as the spintronic device <NUM> or the sensing element <NUM> of the read head <NUM> shown in <FIG>. The spintronic device <NUM> may be utilized within a magnetic sensor outside of the context of a read head such as in <FIG>, or a magnetic recording write head to provide an AC field (e.g., as part of a spin torque oscillator (STO) for MAMR. As shown in <FIG>, a seed layer <NUM> is disposed over a main pole <NUM>, the multilayer structure <NUM> is disposed over the seed layer <NUM>, a spacer <NUM> is disposed over the multilayer structure <NUM>, a magnetic layer <NUM>, such as a spin polarization layer (SPL) or a spin torque layer (STL) is disposed over the spacer <NUM>, and a trailing shield <NUM> is disposed over the magnetic layer <NUM>.

The multilayer structure <NUM> may be a FGL. The main pole <NUM> includes a magnetic material, such as CoFe, CoFeNi, or FeNi, other suitable magnetic materials. The seed layer <NUM> may comprise a NiFeTa/Ru/Cr multilayer structure. The spacer <NUM> may comprise Cu, NiAl, or a Ag-based material. A thin layer of Cr or V may optionally be inserted between the multilayer structure <NUM> and the spacer <NUM> to enhance the negative interfacial scattering effect. The magnetic layer <NUM> may comprise NiFe, CoMnGe, or CoFe. The trailing shield <NUM> includes a magnetic material, such as CoFe, FeNi, or other suitable magnetic materials, serving as a second electrode and return pole for the main pole <NUM>. The main pole <NUM> may be the main pole <NUM> of <FIG> and the trailing shield may be the TS <NUM> of <FIG>. As utilized in the spintronic device <NUM>, the multilayer structure <NUM> may comprise between five to ten layers 302a-302n, for example, resulting in a total thickness of the multilayer structure <NUM> being between about <NUM> to about <NUM>.

<FIG> illustrates a schematic MFS view of a spintronic device or MR sensor <NUM> utilizing the multilayer structure <NUM> of <FIG>, according to one embodiment. The spintronic device or MR sensor <NUM> may be used as the sensing element <NUM> or the spintronic device <NUM> of the read head <NUM> shown in <FIG>. The MR sensor <NUM> may be utilized in an MR device, a magnetic recording read head, or a magnetic sensor outside of the context of a read head such as in <FIG>. For example, the spintronic device or MR sensor <NUM> may be utilized in a tunneling magnetoresistance (TMR) device, in a giant magnetoresistance (GMR) device, in a current-in-plane (CIP) GMR device, or in a current-perpendicular-to-plane (CPP) GMR device. The MR sensor <NUM> of <FIG> may be interchangeably referred to as spintronic device <NUM> throughout.

As shown in <FIG>, a spacer layer <NUM> is disposed on the multilayer structure <NUM>, a first pinned layer <NUM> is disposed on the spacer layer <NUM>, a barrier layer <NUM> is disposed on the first pinned layer <NUM>, and a free layer <NUM> is disposed on the barrier layer <NUM>. In the spintronic device or MR sensor <NUM>, the multilayer structure <NUM> may be a second pinned layer, where the magnetizations of the first pinned layer <NUM> and the multilayer structure <NUM> are anti-parallel to each other. In a MR device, the multilayer structure <NUM> may be disposed over a first shield (not shown), and a second shield (not shown) may be disposed over the free layer <NUM>. Furthermore, one or more layers may be disposed between the multilayer structure <NUM> and the first shield, such as a seed layer and/or a spacer layer, and one or more layers may be disposed between the free layer <NUM> and the second shield, such as a cap layer.

The first pinned layer <NUM> is magnetic and is formed of a material that includes one or more of Co, Fe, B, Ni, and/or an alloy thereof, such as CoFe or NiFe. The first pinned layer <NUM> may have a positive spin polarization, whereas the multilayer structure <NUM> has a negative spin polarization. The spacer layer <NUM> is nonmagnetic and is formed of a metal material, such as Ru. The spacer layer <NUM> facilitates the magnetizations of the first pinned layer <NUM> and the multilayer structure <NUM> being anti-parallel to each other. The barrier layer <NUM> is nonmagnetic and includes MgO, aluminum oxide (AlxOx) such as Al<NUM>O<NUM>, or any other suitable insulation material. The free layer <NUM> is formed of a material that includes one or more of Ni, Fe, Co, B, and/or Hf.

<FIG> is a schematic view of certain embodiments of a memory cell array <NUM> in a cross-point configuration. The memory cell array <NUM> is comprised of a plurality of memory cells <NUM> formed out of spintronic devices, such as SOT-based MRAM devices. In some embodiments, each memory cell <NUM> of the memory cell array <NUM> comprises the spintronic device <NUM> of <FIG> including the multilayer structure <NUM>. In other embodiments, the memory cells <NUM> of the memory cell array <NUM> may comprise other types of spintronic devices comprising the multilayer structure <NUM> of <FIG>, such as the spintronic device <NUM> of <FIG>.

Each of the memory cells <NUM> may be in a state representing either a <NUM> or a <NUM> bit value. The memory cell array <NUM> comprises a plurality of bottom electrodes <NUM> and a plurality of spin Hall electrodes or spin orbit material electrodes <NUM>. The spin orbit material electrodes <NUM> comprise the multilayer structure <NUM> of <FIG>. Each memory cell <NUM> may be part of a two-terminal device or a three terminal device. For example, in two-terminal devices, the bottom electrodes <NUM> may serve as bit lines, and the spin orbit material electrodes <NUM> may serve as word lines. For example, in three-terminal devices, the bottom electrode <NUM> can serve as bit lines and read word lines and the spin orbit material electrodes <NUM> may service as write word lines.

The cross-point array implementation as shown in <FIG> is just an example MRAM implementation, and the various spintronic device embodiments disclosed herein can be implemented in other types of MRAM devices. As such, the memory cell array <NUM> is not intended to be limiting. Other architectures of the memory cell array <NUM> are possible including various types and combinations of terminals, gates, transistors, and lines.

<FIG> illustrates a graph <NUM> showing the Hk in Tesla (T), the saturation magnetic flux density (Bs) in T, and the effective magnetization (Meff) in T of the multilayer structure <NUM> of <FIG> as the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> are varied in nm, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

In the graph <NUM>, the first sublayer <NUM> comprises FeCr<NUM>, and the second sublayer <NUM> comprises Co. While the first sublayer <NUM> comprises FeCr<NUM> in the embodiment shown in the graph <NUM>, the first sublayer <NUM> may instead comprise FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, FeCrxVyTiz, or other FeCrx materials discussed above, and the first sublayer <NUM> is not intended to be limited to only FeCr<NUM>. Furthermore, the second sublayer <NUM> may comprise one or more of Cr and V as well, as discussed above. Similar results are expected when the first sublayer <NUM> comprises Fe and the second sublayer <NUM> comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz, where the value of each of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. As such, the graph <NUM> is not intended to be limited to only FeCr<NUM> as the material of the first sublayer <NUM> and Co as the material of the second sublayer <NUM>.

The thickness <NUM> of the first sublayer <NUM> is shown on the bottom of the graph along the x-axis while the thickness <NUM> of the second sublayer <NUM> is shown on the top of the graph <NUM> along the x-axis. The graph <NUM> is broken down into several portions <NUM>-<NUM>. In each of the portions <NUM>-<NUM>, the first sublayer <NUM> varies in thickness from about <NUM> to about <NUM>. In the first portion <NUM>, the second sublayer <NUM> has a thickness of about <NUM>. In the second portion <NUM>, the second sublayer <NUM> has a thickness of about <NUM>. In the third portion <NUM>, the second sublayer <NUM> has a thickness of about <NUM>. In the fourth portion <NUM>, the second sublayer <NUM> has a thickness of about <NUM>. In the fifth portion <NUM>, the second sublayer <NUM> has a thickness of about <NUM>.

The graph <NUM> illustrates that a negative Hk of about -<NUM> T is achieved when the first sublayer <NUM> has a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> has a thickness <NUM> of about <NUM> to about <NUM>. The graph <NUM> further illustrates that larger Meff and Bs are achieved when the first sublayer <NUM> has a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> has a thickness <NUM> of about <NUM> to about <NUM>.

<FIG> illustrates a graph <NUM> showing the current-in-plane (CIP) giant magnetoresistance (GMR) (%) in the device <NUM> of <FIG> utilizing a pinned layer <NUM> comprising CoFe and the multilayer structure <NUM> of <FIG> as the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> of the multilayer structure <NUM> are varied in nm, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

The thickness <NUM> of the first sublayer <NUM> is shown on the y-axis, the thickness <NUM> of the second sublayer <NUM> is shown on the x-axis, and the negative CIP-GMR achieved is indicated by the key <NUM>. A negative CIP-GMR indicates that the multilayer <NUM> has a negative spin polarization since the pinned layer comprising CoFe has a positive spin polarization. As shown by the arrow <NUM>, the first sublayer <NUM> having a larger thickness <NUM> of about <NUM> to about <NUM> and the second sublayer <NUM> having a thickness between about <NUM> to about <NUM> results in a higher negative spin polarization.

<FIG> illustrates a graph <NUM> showing the Hk in T as the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> of the multilayer structure <NUM> of <FIG> are varied in nm, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

In the graph <NUM>, the first sublayer <NUM> comprises FeCr<NUM>, and the second sublayer <NUM> comprises Co. While the first sublayer <NUM> comprises FeCr<NUM> in the embodiment shown in the graph <NUM>, the first sublayer <NUM> may instead comprise FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, FeCrxVyTiz, or other FeCrx materials discussed above, and similar results would be obtained. Furthermore, the second sublayer <NUM> may comprise one or more of Cr and as well, as discussed above. Similar results are expected when the first sublayer <NUM> comprises Fe and the second sublayer <NUM> comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz, where the value of each of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. As such, the graph <NUM> is not intended to be limited to only FeCr<NUM> as the material of the first sublayer <NUM> and Co as the material of the second sublayer <NUM>.

The thickness <NUM> of the first sublayer <NUM> is shown on the y-axis, the thickness <NUM> of the second sublayer <NUM> is shown on the x-axis, and the Hk achieved is indicated by the key <NUM>. Line <NUM> illustrates an approximate boundary of the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> that achieve the highest negative Hk. As shown by line <NUM>, the first sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> results in a Hk of about -<NUM> T to about -<NUM> T.

Line <NUM> illustrates or encompasses an approximate boundary of the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> that achieve the highest negative Hk and the highest negative spin polarization using the data from graph <NUM> of <FIG>. As shown by line <NUM>, the first sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> results in the highest negative Hk and the highest negative spin polarization collectively.

<FIG> illustrates a graph <NUM> showing the Meff in T as the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> of the multilayer structure <NUM> of <FIG> are varied in nm, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

The thickness <NUM> of the first sublayer <NUM> is shown on the y-axis, the thickness <NUM> of the second sublayer <NUM> is shown on the x-axis, and the Meff achieved is indicated by the key <NUM>. Line <NUM> illustrates or encompasses an approximate boundary of the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> that achieve the highest Meff. As shown by line <NUM>, the first sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> results in a Meff of about <NUM> T to about <NUM> T.

Line <NUM> illustrates or encompasses an approximate boundary of the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> that achieve the highest Meff and the highest negative spin polarization using the data from graph <NUM> of <FIG>. As shown by line <NUM>, the first sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> and the second sublayer <NUM> having a thickness <NUM> between about <NUM> to about <NUM> results in the highest Meff and the highest negative spin polarization collectively.

Thus, taking each of the graphs <NUM>, <NUM>, <NUM> of <FIG> into consideration, the thicknesses <NUM>, <NUM> of the first and second sublayers <NUM>, <NUM> may be selected based on the desired overall properties of the multilayer structure <NUM> within the device. For example, if a higher Meff is desired, the first sublayer <NUM> may have a thickness of about <NUM> to about <NUM>, whereas if a higher negative Hk is desired, the first sublayer <NUM> may have a thickness of about <NUM> to about <NUM>. As such, the multilayer structure of the multilayer structure <NUM> may be tailored or modified as needed to produce the desired properties.

<FIG> illustrates a graph <NUM> showing CIP-GMR ratio in % in the device <NUM> of <FIG> utilizing a pinned layer <NUM> comprising CoFe and the multilayer structure <NUM> of <FIG> as the atomic percent (at%) of Cr of the first sublayer <NUM> comprising FeCrX of the multilayer structure <NUM> is varied, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

While the first sublayer <NUM> comprises FeCrX in the embodiment shown in the graph <NUM>, the first sublayer <NUM> may instead comprise FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz, in which case the atomic percentage of Cr, V, and/or Ti would be varied in a similar manner to achieve similar results. Furthermore, the second sublayer <NUM> may comprise one or more of Cr and as well, as discussed above. Similar results are expected when the first sublayer <NUM> comprises Fe and the second sublayer <NUM> comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz, where the value of each of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. As such, the graph <NUM> is not intended to be limited to only FeCrx as the material of the first sublayer <NUM> and Co as the material of the second sublayer <NUM>.

As shown in the graph <NUM>, Cr in an atomic percent between about <NUM>% to about <NUM>% results in the largest negative CIP-GMR of about -<NUM>% to about -<NUM>% when the first sublayer <NUM> has a thickness of about <NUM>. Furthermore, Cr in an atomic percent between about <NUM>% (i.e., FeCr<NUM>) results in a negative CIP-GMR of about -<NUM>% to about -<NUM>%.

<FIG> illustrates a graph <NUM> showing the Hk in T, the Bs in T, and the Meff in T of the multilayer structure <NUM> of <FIG> as the atomic percent (at%) of Cr of the first sublayer <NUM> comprising FeCrX is varied, according to one embodiment. The multilayer structure <NUM> may be within a spintronic device, such as the spintronic device <NUM> of <FIG>, the spintronic device <NUM> of <FIG>, or the MR sensor <NUM> of <FIG>.

While the first sublayer <NUM> comprises FeCrX in the embodiment shown in the graph <NUM>, the first sublayer <NUM> may instead comprise FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz, in which case the atomic percentage of Cr, V, and/or Ti would be varied in a similar manner to achieve similar results. Furthermore, the second sublayer <NUM> may comprise one or more of Cr and as well, as discussed above. Similar results are expected when the first sublayer <NUM> comprises Fe and the second sublayer <NUM> comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz, where the value of each of x, y, and/or z in each is a positive number, and may be a non-integer value or an integer value. As such, the graph <NUM> is not intended to be limited to only FeCrX as the material of the first sublayer <NUM> and Co as the material of the second sublayer <NUM>.

As shown by the graph <NUM>, Cr in an atomic percent between about <NUM>% (i.e., FeCr<NUM>) results in a Meff of about <NUM> T to about <NUM> T and a Hk of about -<NUM> T. Thus, taking each of the graphs <NUM>, <NUM> of <FIG> into consideration, the FeCrX composition of the first sublayer <NUM> may be selected based on the desired overall properties of the multilayer structure <NUM> within the device. For example, if a higher Meff or a higher negative Hk is desired, the first sublayer <NUM> may comprise FeCr<NUM>, whereas if a higher negative spin polarization is desired, the first sublayer <NUM> may comprise FeCr<NUM>. As such, the multilayer structure of the multilayer structure <NUM> may be tailored or modified as needed to produce the desired properties.

Therefore, utilizing a multilayer structure comprising alternating layers of Co and Fe, where at least one of the Co or Fe layers comprise one or more of Cr and V, both a negative spin polarization and a negative anisotropic field can be achieved. Furthermore, the various parameters of the multilayer structure may be modified as need to produce desired properties of the multilayer structure, such as varying the thickness of the Co and Fe sublayers or varying the composition of Cr and V used. As such, spintronic devices, such as spintronic devices included within MAMR, CPP-GMR, and MRAM devices, have more freedom, resulting in more effective and improved devices.

The first sublayer comprises one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz. The value of each of x, y, and z is a positive number. The second sublayer comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz. The value of each of x, y, and z is a positive number. Each of the first sublayers has a first thickness between about <NUM> to about <NUM>. Each of the second sublayers has a second thickness between about <NUM> to about <NUM>. The multilayer structure is a free layer, a pinned layer, or a field generating layer. A magnetic media drive comprises the spintronic device. A magnetoresistive random access memory device comprises the spintronic device. A magnetic sensor comprises the spintronic device. A magnetic recording head comprises the spintronic device.

The multilayer structure is a free layer, a pinned layer, or a field generating layer. Each of the first layers has a first thickness between about <NUM> to about <NUM> and each of the second layers has a second thickness between about <NUM> to about <NUM>. The first layers each comprises one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz. Each of x, y, and z is a number between <NUM> and <NUM>. The second layers each comprises one of CoCrx, CoVx, CoTix, CoCrxVy, CoCrxTiy, CoVxTiy, or CoCrxVyTiz. Each of x, y, and z is a number between <NUM> and <NUM>. The cap layer is an additional first layer comprising FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz having the first thickness. A magnetic media drive comprises the spintronic device. A magnetoresistive random access memory device comprises the spintronic device. A magnetic sensor comprises the spintronic device. A magnetic recording head comprises the spintronic device.

In yet another embodiment, a spintronic device comprises a multilayer structure having a negative spin polarization and a negative anisotropic field, the multilayer structure comprising a plurality of alternating first layers and second layers. Each of the first layers comprises at least one of FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, and FeCrxVyTiz, where each of x, y, and z is a positive number, and each of the second layers comprising Co. Each of the first layers has a first thickness between about <NUM> to about <NUM> and each of the second layers has a second thickness between about <NUM> to about <NUM>. The spintronic device further comprises one or more layers disposed over the multilayer structure.

The one or more layers comprise a cap layer disposed in contact with the multilayer structure, the cap layer being an additional first layer comprising FeCrx, FeVx, FeTix, FeCrxVy, FeCrxTiy, FeVxTiy, or FeCrxVyTiz having the first thickness. The multilayer structure is a free layer, a pinned layer, or a field generating layer. The negative anisotropic field of the multilayer structure is between about -<NUM> T to about -<NUM> T, and an effective magnetization of the multilayer structure is between about <NUM> T to about <NUM> T. Each of the second layers further comprises one or more of Cr and V. A magnetic media drive comprises the spintronic device. A magnetoresistive random access memory device comprises the spintronic device. A magnetic sensor comprises the spintronic device. A magnetic recording head comprises the spintronic device.

Claim 1:
A spintronic device, comprising:
a multilayer structure (<NUM>) having a negative spin polarization and a negative anisotropic field (-Hk), the multilayer structure comprising a plurality of layers (302a-302n), each layer of the plurality of layers comprising a first sublayer (<NUM>) comprising Fe and a second sublayer (<NUM>) comprising Co and wherein the first and second sublayers are alternating, characterized in that at least one of the first sublayer and the second sublayer further comprise one or more of Cr and V.