Spinning electronic device with adjustable spin current spatial distribution and polarization direction

Abstract

The invention discloses a spin current spatial distribution and polarization direction adjustable spin electronic device, which comprises a substrate, and is characterized in that the substrate is provided with a non-magnetic spin source layer, a ferromagnetic layer arranged on the non-magnetic spin source layer and a current reforming layer arranged on the ferromagnetic layer; specifically, the non-magnetic spin source layer and the ferromagnetic layer form a heterojunction, and a current reforming layer with a specific plane geometric structure grows on the heterojunction. According to the invention, anisotropic magnetic moment flipping of the spin torque and full electromagnetic moment flipping of the spin torque are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of spintronic devices, and in particular to a spintronic device with adjustable spin current spatial distribution and polarization direction. Background Art

[0002] Spintronics is a newly emerging discipline that has emerged in recent years. Its research findings are widely used in hard drive heads, magnetic random access memory (RAM), spin field emission transistors (SFETs), and spin light-emitting diodes (LEDs). Compared to traditional memory devices, spintronic memory devices offer several advantages, including high storage density, low energy consumption, and fast response times.

[0003] Spin-orbit moment is widely used in spin control of many spintronic devices to achieve information writing and logic operations. However, the spin-orbit moment requires the assistance of an external magnetic field to drive the magnetic moment reversal. This additional magnetic field not only poses challenges to device integration but also affects the stability of the device. Therefore, how to achieve current-driven perpendicular magnetic moment reversal under zero magnetic field has become one of the main challenges in the application of spin-orbit moment. There are currently two main methods to achieve field-free reversal: one is to introduce an in-plane effective magnetic field by using exchange bias or wedge structure, but such methods usually involve complex sample or device structures, which is not conducive to commercial application. The other is to use out-of-plane polarized spin current to break the symmetry of the system and achieve magnetic moment reversal under zero field. This method can also greatly reduce the critical reversal current density and optimize device efficiency, thus showing broad application prospects. Currently, methods to achieve out-of-plane spin polarization include utilizing crystal symmetry or dual metal spin source layers, but their strict material requirements or complex processes undoubtedly increase the production cost, which is contrary to the goal of industrial production to pursue cheap and simple. At the same time, there is still a lack of convenient and effective means to control the out-of-plane spin current. Summary of the Invention

[0004] In response to the shortcomings of the prior art, the present invention aims to provide a spintronic device with adjustable spatial distribution and polarization direction of spin currents. The spintronic device realizes anisotropic magnetic moment reversal of spin torque and full electromagnetic moment reversal of spin torque in the absence of an external field. To achieve the above-mentioned and other advantages of the present invention, a spintronic device with adjustable spatial distribution and polarization direction of spin currents is provided, comprising:

[0005] A substrate, a non-magnetic spin source layer provided on the substrate, a ferromagnetic layer provided on the non-magnetic spin source layer, and a current reshaping layer provided on the ferromagnetic layer;

[0006] Specifically, the non-magnetic spin source layer and the ferromagnetic layer form a heterojunction, and a current reshaping layer with a specific planar geometric structure is grown on the heterojunction.

[0007] Preferably, the current reshaping layer is used to reshape the local spatial current distribution of the device, so as to deflect the effective transport plane of the current and spin current, thereby generating a spin current with controllable direction and intensity.

[0008] Preferably, the current reforming layer is made of a material with high conductivity, including Cu and Au.

[0009] Preferably, the shape of the current reforming layer has n-degree symmetry, where n=1, 2, 3..., and the spin torque magnetic moment reversal anisotropy can be regulated by adjusting the shape of the current reforming layer.

[0010] Preferably, the current density distribution is changed by the current reshaping layer, causing the effective current transport plane to deflect and generate an out-of-plane spin component, thereby realizing the full electromagnetic moment reversal of the spin torque in the absence of an external field.

[0011] Preferably, the current density distribution can be adjusted by changing the relative direction of the current and the current reshaping layer, so that the effective current transport plane is tilted to different degrees, thereby regulating the intensity of the out-of-plane spin polarization.

[0012] Compared with the prior art, the present invention has the following beneficial effects: the method of the present invention has low requirements on the preparation process and is simple and flexible, and is easy to integrate and miniaturize.

[0013] The method of the present invention has strong compatibility and can be applied to various magnetic materials and spintronic devices.

[0014] The present invention can realize the anisotropic magnetic moment reversal of the spin torque and the full electromagnetic moment reversal of the spin torque in the absence of an external field, and is applied to multiple fields such as memory reading and writing and logical operations.

[0015] The present invention utilizes out-of-plane spin polarization to achieve magnetic moment reversal. Compared with the solution utilizing in-plane spin polarization, the critical reversal current involved in the present invention is smaller, thereby reducing the energy consumption level of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A sample structure diagram of a spintronic device with adjustable spin current spatial distribution and polarization direction according to the present invention;

[0017] Figure 2 The effective current transport plane diagrams of the spintronic device with adjustable spin current spatial distribution and polarization direction according to the present invention when the current density is uniformly distributed and the effective current transport plane diagrams when the current density is non-uniformly distributed about the xz plane;

[0018] Figure 3Device diagrams of Ta / Pt / Co / Pt and Ta / Pt / Co / Pt / Cu (Y-type) spintronic devices with adjustable spin current spatial distribution and polarization direction according to the present invention;

[0019] Figure 4 Anomalous Hall curves of Ta / Pt / Co / Pt and Ta / Pt / Co / Pt / Cu (Y-type) of the spintronic device with adjustable spin current spatial distribution and polarization direction according to the present invention;

[0020] Figure 5 The current-driven magnetization reversal curves of Ta / Pt / Co / Pt of the spintronic device with adjustable spin current spatial distribution and polarization direction under zero field and 300Oe auxiliary field respectively;

[0021] Figure 6 The magnetic reversal curves driven by current at different angles under zero field and the trend diagram of the reversal ratio changing with angle for Ta / Pt / Co / Pt / Cu (Y-type) spintronic devices with adjustable spin current spatial distribution and polarization direction according to the present invention are shown;

[0022] Figure 7 A device diagram of Ta / Pt / Co / Pt / Cu (triangle) of a spintronic device with adjustable spin current spatial distribution and polarization direction according to the present invention;

[0023] Figure 8 The graph shows the magnetization reversal curves driven by current at different angles under zero field and the trend of the reversal ratio with angle for the Ta / Pt / Co / Pt / SiO2 (Y-type) spintronic device with adjustable spin current spatial distribution and polarization direction according to the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Reference Figure 1 A spintronic device with adjustable spin current spatial distribution and polarization direction, comprising: a substrate 1, a non-magnetic spin source layer 2 provided on the substrate 1, a ferromagnetic layer 3 provided on the non-magnetic spin source layer 2, and a current reshaping layer 4 provided on the ferromagnetic layer 3;

[0026] Specifically, the non-magnetic spin source layer 2 and the ferromagnetic layer 3 form a heterojunction, on which a current reshaping layer 4 with a specific planar geometry is grown. Changing the relative orientation of the current and the current reshaping layer 4 can adjust the current density distribution, resulting in varying degrees of tilt in the effective current transport plane, thereby regulating the strength of the out-of-plane spin polarization.

[0027] Further, as attached Figure 2 (Left) shows the effective current transport plane of the non-magnetic spin source layer in the non-magnetic spin source / ferromagnetic functional layer heterojunction. When the current JC flows along the x direction and is evenly distributed in the spin source layer, the spin current polarization direction σ generated in the spin current source layer will be along the y direction. Figure 2 As shown in the figure (right), if the current distribution is asymmetric about the xz plane, the effective current transport plane will rotate about the x-axis away from the xy plane. In this case, the spin current polarization direction σ will have a z-direction component. The greater the asymmetry of the current distribution about the xz plane, the greater the tilt of the effective current transport plane, and the stronger the out-of-plane spin polarization.

[0028] Furthermore, the present invention regulates the spin current polarization direction and the out-of-plane spin current intensity by adjusting the current density distribution.

[0029] Furthermore, the current reforming layer 4 is made of a material with high conductivity, including Cu and Au. The current reforming layer 4 is used to reform the local spatial current distribution of the device, deflecting the effective transport plane of current and spin current, and generating a spin current with controllable direction and intensity.

[0030] Furthermore, in the spintronic device, by changing the relative direction of the current and the current reshaping layer 4, the degree of deflection of the effective current transport plane around the current direction is different, resulting in out-of-plane spin currents of different intensities, and the ratio of current-driven magnetization reversal varies with the direction.

[0031] Furthermore, the shape of the current reshaping layer 4 has n-degree symmetry, n = 1, 2, 3..., the degree of deflection of the current effective transport plane around the current direction and the resulting out-of-plane spin current intensity oscillate with the current direction and are periodic, and the period depends on the symmetry. By adjusting the shape of the current reshaping layer, the anisotropy of the spin torque and magnetic moment reversal can be controlled.

[0032] Furthermore, by introducing the current reshaping layer 4, the current density distribution is changed, causing the effective current transport plane to deflect and generating an out-of-plane spin component, the full electromagnetic moment reversal of the spin torque can be achieved without an external field.

[0033] Furthermore, the device can be used to construct a storage unit of a magnetic random access memory and an operation unit of a spin logic device.

[0034] Furthermore, a method for preparing a spintronic device with adjustable spin current spatial distribution and polarization direction is as follows:

[0035] 1. Place the Si / SiO2 substrate 1 with a length of 10 mm and a width of 10 mm on a round tray and transfer it into the magnetron sputtering chamber. The background vacuum in the magnetron sputtering chamber is 6.65×10 -6 Pa, argon gas with a purity of 99.99% was introduced into the magnetron sputtering chamber, and the argon flow rate was adjusted to keep the argon pressure at 0.45 Pa. Ta, Pt, Co, and Pt thin films were grown on the substrate in sequence by magnetron sputtering. The sputtering power of the Ta target was 100 W, the sputtering power of the Pt target was 30 W, and the sputtering power of the Co target was 40 W.

[0036] 2. Anneal the sample at 350° for 1 hour to improve the verticality of the sample.

[0037] 3. Spin-coat negative photoresist on the sample, expose it with UV lithography system, develop it in developer, and then use Ar ion etching to prepare the Hall device pattern. Use PG remover solution to remove the photoresist to obtain the Hall bar device, as shown in the attached figure. Figure 3 (Left).

[0038] 4. Spin-coat positive photoresist, expose with UV lithography system, and develop in developer to obtain a Y-shaped pattern in the center of the device. Then, magnetron sputtering is used to prepare a Y-shaped conductive Cu layer. The background vacuum of the magnetron sputtering chamber is 6.65×10 -6 Pa, the argon pressure is maintained at 0.45 Pa, and the sputtering power of the Cu target is 40 W. Finally, the photoresist is removed by cleaning with LOR solution to obtain the attached Figure 3 (middle) The angle in the lower right corner of the figure represents the relative direction φ of the current and the Y-shaped Cu layer, and the definition of the attached Figure 3 The relative direction φ of (middle) is 0°, and then the Y shape is rotated clockwise in units of 15° to produce devices with different relative directions. Figure 3 (Right) The device is Y-shaped and rotated 30° clockwise.

[0039] Figure 4 These are the anomalous Hall curves of Ta / Pt / Co / Pt and Ta / Pt / Co / Pt / Cu (Y-type) samples, indicating that the samples have perpendicular magnetic anisotropy before and after the growth of the current reforming layer 4.

[0040] Figure 5 These are the current-driven magnetization reversal curves of Ta / Pt / Co / Pt under zero field and 300Oe auxiliary field, respectively. In the absence of a current reforming layer, an auxiliary field is required to achieve magnetic moment reversal.

[0041] Figure 6The magnetic reversal curves and the reversal ratio of the Ta / Pt / Co / Pt / Cu (Y-type) sample driven by current at different angles φ under zero field are shown. The variation of the reversal ratio with angle φ indicates that the magnetic moment reversal of the spin torque is anisotropic. When φ = 30° and 90°, the current direction is parallel to the symmetry direction. The current density distribution is symmetric about the xz plane, and the reversal ratio is close to zero. When φ = 0°, 60°, and 120°, the current direction is perpendicular to the symmetry direction, and the current density distribution is extremely asymmetric about the xz plane, resulting in the maximum field-free reversal ratio. The current density distribution depends on φ, so the reversal ratio oscillates with φ. Because the Y-type sample has three-dimensional symmetry, the oscillation is also periodic with a period of 120°.

[0042] Figure 7 This is a diagram of a Ta / Pt / Co / Pt / Cu (triangular) device. The shape of the device is not limited to a Y-shape and can also be made into other shapes, so corresponding adjustments can be made according to actual needs.

[0043] Figure 8 Figure 1 shows a Ta / Pt / Co / Pt / SiO2 (Y-shaped) device, showing the current-driven magnetization reversal curves and the reversal ratio as a function of angle under zero field. Since SiO2 is non-conductive and cannot alter the current density distribution, the reversal ratios in all directions are close to zero, and the current-driven reversal exhibits no anisotropy.

[0044] The number of devices and processing scales described herein are intended to simplify the description of the present invention, and the application, modification, and variation of the present invention will be apparent to those skilled in the art. Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiment. They can be applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily implemented. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

1. A spintronic device with adjustable spin current spatial distribution and polarization direction, characterized in that: include: A substrate (1), a non-magnetic spin source layer (2) provided on the substrate (1), a ferromagnetic layer (3) provided on the non-magnetic spin source layer (2), and a current reshaping layer (4) provided on the ferromagnetic layer (3); Specifically, the non-magnetic spin source layer (2) and the ferromagnetic layer (3) form a heterojunction, and a current reshaping layer (4) with a specific planar geometric structure is grown on the heterojunction.

2. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, wherein: The current reshaping layer (4) is used to reshape the local spatial current distribution of the device, so as to deflect the effective transport plane of the current and spin current, thereby generating a spin current with controllable direction and intensity.

3. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, characterized in that: The current reforming layer (4) is made of a material with high conductivity, including Cu and Au.

4. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, characterized in that: The shape of the current reshaping layer (4) has n-degree symmetry, where n=1, 2, 3..., and the spin torque magnetic moment reversal anisotropy is regulated by adjusting the shape of the current reshaping layer.

5. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, characterized in that: The current density distribution is changed by the current reshaping layer (4), causing the effective current transport plane to deflect, generating an out-of-plane spin component, and realizing the full electromagnetic moment reversal of the spin torque without an external field.

6. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, characterized in that: The current density distribution can be adjusted by changing the relative direction between the current and the current reshaping layer (4), so that the effective current transport plane is tilted to different degrees, thereby regulating the intensity of the out-of-plane spin polarization.

7. The spintronic device with adjustable spin current spatial distribution and polarization direction according to claim 1, characterized in that: The device is used to construct a storage unit of a magnetic random access memory and an operation unit of a spin logic device.

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