CN115171747A - Method for regulating and controlling magnetic domain overturning in antiferromagnetic structure by using current - Google Patents

Method for regulating and controlling magnetic domain overturning in antiferromagnetic structure by using current Download PDF

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CN115171747A
CN115171747A CN202210759424.0A CN202210759424A CN115171747A CN 115171747 A CN115171747 A CN 115171747A CN 202210759424 A CN202210759424 A CN 202210759424A CN 115171747 A CN115171747 A CN 115171747A
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magnetic
current
magnetic layer
layer
direction current
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周艳
赵月雷
杨晟
武凯
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Chinese University of Hong Kong Shenzhen
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Chinese University of Hong Kong Shenzhen
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices

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Abstract

The invention relates to a method for regulating and controlling magnetic domain overturning in an antiferromagnetic structure by using current, which comprises the following steps: providing an antiferromagnetic film, wherein the antiferromagnetic film structure comprises a first magnetic layer, a nonmagnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of the magnetic moment in the first magnetic layer is antiparallel to the direction of the magnetic moment in the second magnetic layer; applying a magnetic field and a first direction current to induce a magnetic domain wall, wherein the magnetic domain wall is positioned at the diagonal position of the antiferromagnetic film; withdrawing the magnetic field, applying current in a second direction, wherein the magnetic domain wall is vertical to the current in the second direction; applying a third direction current, translating the magnetic domain wall along the third direction current, and completely turning the magnetic domains in the first magnetic layer and the second magnetic layer; the first direction current is opposite to the second direction current, and the first direction current is the same as the third direction current. The invention has the advantages that the distortion motion of the magnetic domain wall occurs in the antiferromagnetic structure, so that the magnetic moment in the device can be completely overturned, and the device can work normally.

Description

Method for regulating and controlling magnetic domain overturning in antiferromagnetic structure by using current
Technical Field
The invention relates to the technical field of magnetic memory devices, in particular to a method for switching magnetic domains in a current regulation and control antiferromagnetic structure.
Background
Spin orbit torque Magnetic Random Access Memory (MRAM) and spin transfer torque MRAM (spin transfer torque) both use a current to turn a magnetic layer in a magnetic tunnel junction, thereby implementing an information writing operation. Compared with the spin orbit torque magnetic random access memory, the spin orbit torque magnetic random access memory has more advantages, current does not flow through the tunneling layer during writing operation, and the problems of device breakdown and the like caused by a thermal effect are obviously reduced. The spin orbit torque magnetic random access memory converts a current into a spin current by using the spin orbit coupling property of a heavy metal such as Pt or Ta, and switches a magnetic layer by using the spin current. However, to realize the switching of the magnetic layer, the in-plane symmetry of the magnetic moment must be broken, and an in-plane magnetic field needs to be additionally applied, which results in that the device cannot realize high integration. Later researchers proposed various methods to break the symmetry of magnetic moment, such as using exchange bias or adding an in-plane magnetic layer, etc., and also could grow the magnetic layer or heavy metal layer into a wedge-shaped film to generate non-uniform spin current to break the symmetry of magnetic moment in-plane.
However, in the conventional domain wall motion method, once the domain wall twisting motion occurs, the magnetic moment in the device cannot be completely reversed, and thus the device fails.
Disclosure of Invention
According to the problems in the prior art, the invention provides a method for switching magnetic domains in a current regulation and control antiferromagnetic structure, so that a device can work normally.
The technical scheme of the invention is as follows:
a method for regulating domain switching in an antiferromagnetic structure with a current comprising:
providing an antiferromagnetic film, wherein the antiferromagnetic film structure comprises a first magnetic layer, a non-magnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of the magnetic moment in the first magnetic layer is antiparallel to the direction of the magnetic moment in the second magnetic layer;
applying a magnetic field and a first direction current to induce a magnetic domain wall, wherein the magnetic domain wall is positioned at the diagonal position of the antiferromagnetic film;
withdrawing the magnetic field and the current in the first direction, and applying the current in the second direction, wherein the magnetic domain wall is vertical to the current in the second direction;
applying a current in a third direction, wherein the magnetic domain wall moves horizontally along the current in the third direction, and the magnetic domains in the first magnetic layer and the second magnetic layer are completely turned over;
the first direction current is opposite to the second direction current, and the first direction current is the same as the third direction current.
As a preferable technical scheme, the first magnetic layer and the second magnetic layer are both of a Co/Pt multilayer film structure; the first magnetic layer and the second magnetic layer are both perpendicular magnetic layers, and the first magnetic layer and the second magnetic layer are in a ferromagnetic exchange-coupled state.
Preferably, the nonmagnetic metal layer is a nonmagnetic Ru layer.
Preferably, the thickness of the nonmagnetic metal layer is 1.25-1.35nm.
Preferably, the ratio of the magnetic domains in the first magnetic layer to the magnetic domains in the second magnetic layer on both sides of the magnetic domain wall is 45% -55%.
Preferably, the magnetic field intensity is 60mT; the first direction current intensity was 30mA and the first direction current was parallel to the antiferromagnetic film.
As a preferable technical scheme, the magnetic field is reduced to 0mT, and the first direction current is reduced to 0mA; a second direction current is applied with a strength of 30mA and opposite to the first direction current, so that the magnetic domain walls are moved perpendicular to the second direction current.
As a preferable technical scheme, the intensity of the current in the third direction is 30mA, and the current in the third direction is the same as the current in the first direction.
As a preferred technical solution, the complete inversion is that the magnetic domains in the first magnetic layer are all inverted into the magnetic domains in the second magnetic layer, or the complete inversion is that the magnetic domains in the second magnetic layer are all inverted into the magnetic domains in the first magnetic layer.
The embodiment of the invention provides a storage element, which comprises an antiferromagnetic film, wherein an antiferromagnetic film structure comprises a first magnetic layer, a non-magnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of magnetic moment in the first magnetic layer is antiparallel to the direction of magnetic moment in the second magnetic layer;
and the driving module is electrically connected with the antiferromagnetic film and is used for controlling the antiferromagnetic film to execute the method.
The technical scheme adopted by the invention has the following beneficial effects: the magnetic domain wall is induced by the external magnetic field under the condition of the external magnetic field, and the position of the magnetic domain wall is further regulated and controlled to be in a diagonal position; and then, the distortion mode is inhibited by removing the magnetic field and applying reverse current, and the magnetic domain is completely turned over mainly by the rigid mode, so that the device can work normally.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments are briefly introduced below to form a part of the present invention, and the exemplary embodiments and the description thereof illustrate the present invention and do not limit the present invention. In the drawings:
fig. 1 is a schematic flow chart illustrating a magnetic domain flipping method in a current-controlled antiferromagnetic structure according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a thin film structure according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a Hall device according to an embodiment of the present invention;
FIG. 4 is a diagram of (a) the evolution process of the magnetic domain in the device under the condition of applying the external magnetic field and the current simultaneously according to an embodiment of the present invention; (b) a schematic diagram of a combination of magnetic structures corresponding to different magnetic domains; (c) The magnetic domain wall applies the motion of a plurality of current pulses at zero field, N being the number of applied pulses; (d) The domain walls exert the motion of a plurality of current pulses at a constant external field.
Fig. 5 is a schematic diagram of a domain flipping method in a current-controlled antiferromagnetic structure according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. In the description of the present invention, it is noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
Once the distortion motion of the magnetic domain wall occurs in the existing magnetic domain wall motion mode, the magnetic moment in the device can not be completely turned over, thereby failing.
In view of the above, according to fig. 1, an embodiment of the present invention provides a method for current-controlling domain switching in an antiferromagnetic structure, including:
step 100, providing an antiferromagnetic film, wherein the antiferromagnetic film structure comprises a first magnetic layer, a nonmagnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of the magnetic moment in the first magnetic layer is antiparallel to the direction of the magnetic moment in the second magnetic layer;
step 101, applying a magnetic field and a first direction current to induce a magnetic domain wall, wherein the magnetic domain wall is positioned at a diagonal position of an antiferromagnetic film;
step 102, removing the magnetic field and the current in the first direction, and applying the current in the second direction, wherein the magnetic domain wall is perpendicular to the current in the second direction;
step 103, applying a current in a third direction, translating the magnetic domain wall along the current in the third direction, and completely turning over the magnetic domains in the first magnetic layer and the second magnetic layer;
the first direction current is opposite to the second direction current, and the first direction current is the same as the third direction current.
A flexible twisting motion mode of a magnetic domain wall is provided, which is influenced by an external vertical magnetic field. A first motion mode: the motion and the rigid body of the domain wall are very close when the magnetic field is close to 0 mT. When the magnetic field is gradually increased, the domain wall is in a twisted motion mode, i.e., a second motion mode. The magnetic domain wall is induced by the external magnetic field under the condition of the external magnetic field, and the position of the magnetic domain wall is further regulated and controlled to be in a diagonal position; and then the magnetic field is removed, the twisting mode is inhibited in a mode of applying reverse current, and the magnetic domain is completely overturned mainly by the rigid mode, so that the device can work normally.
In one embodiment of the present invention, step 100 comprises:
preparing a device:
according to fig. 2, the specific structure of the thin film of the antiferromagnetic structure is:
Ta(5)/[Pt(0.5)/Co(0.5)] 3 /Ru(1.3)/[Co(0.5)/Pt(0.5)] 3 ta (5) in nanometer unit for the bottom and the protective layer, wherein the first magnetic layer is [ Pt (0.5)/Co (0.5) ]] 3 The second magnetic layer is [ Co (0.5)/Pt (0.5) ]] 3 And the first magnetic layer and the second magnetic layer are both perpendicular magnetic layers.
The film is grown on the silicon chip shown in the photoetching device figure 3, the ultra-high vacuum magnetron sputtering instrument of AJA is adopted to plate 5nm of Ta as a buffer layer, then a Pt/Co periodic structure is adopted, and finally 5nm of Ta is plated as a protective layer.
After the growth is finished, the photoresist on the surface of the silicon wafer is cleaned by acetone ultrasonic waves, so that only the device with the shape as shown in figure 3 is left on the silicon wafer. It is emphasized here that the functionality of the device is very critical for the thickness of the non-magnetic metallic material Ru, and the thickness variation range has to be controlled between 1.25-1.35nm.
Characterization of device characteristics:
magneto-optical kerr is a technique that can be used to detect magnetic domain images of magnetic films, with the advantages of accuracy and real-time. This sample was characterized for its magnetic domain distribution using a magneto-optical kerr microscope.
For example, the variation of the magnetic domains in the device with the external magnetic field in case of simultaneous application of the external magnetic field and the current is demonstrated according to fig. 4. The magnetic field is first set to-200 mT, when both the first magnetic layer and the second magnetic layer point in the direction of the external magnetic field, which we mark as domain a, corresponding to structure a in fig. 4 (b). As the magnetic field increases to-84 mT, the magnetic domain B 1 Nucleation begins and gradually occupies the entire device. As the magnetic field continues to increase to 40mT, the magnetic domain B 2 Nucleates and occupies about half the area of the device, i.e., 45% -55%. When the magnetic field is further increased, the magnetic domain B 2 Gradually filling the entire device. When the magnetic field is increased to 90mT, the domain C nucleates and occupies the entire device.
From FIG. 4 (a) we can see the magnetic domainsB 1 And B 2 It can coexist, and the magnetic domain wall can be driven by current. We studied the law between the motion of the domain wall and the external magnetic field carefully, and found two motion modes of the domain wall. In the first motion mode, according to fig. 4 (c), when an external field is applied as 0, the motion of the domain wall is the same as in the conventional domain motion mode, i.e., there is a global translation along the direction of the current, i.e., the velocity is the same at every location on the domain wall. In the second mode of motion, according to figure 4 (d), when an external field of 8mT is applied, the domain wall no longer translates in the direction of the current but rather undergoes significant distortion, when the velocities of motion of the domain wall on the left and right are opposite.
In one embodiment of the present invention, step 101 comprises:
according to fig. 5, the application of current under an applied magnetic field induces a domain wall at a location between 2 and 3, i.e., the anti-ferromagnetic film diagonal. The process can be carried out in the testing link of mass production of devices, and is completely compatible with the mass production process. The step is to inhibit the rigid motion mode of the domain wall, mainly to twist the motion mode, and to make the current no longer work after the domain wall moves to the positions 2 and 3. Such a diagonal domain wall does not achieve complete flipping of the magnetic moment, neither by rigid nor twisting motion. The only way to achieve a complete flip of the magnetic moment is to have the domain wall in the 1 and 2, or 3 and 4, positions and then rigidly move up and down.
Preferably, a magnetic domain wall is induced and positioned at a diagonal position by applying a magnetic field of 60mT and a current of 30mA to the antiferromagnetic structure, and magnetic domains B of the first magnetic layer are distributed on both sides of the magnetic domain wall 1 Magnetic domain B of the second magnetic layer 2 (ii) a Then reducing the magnetic field and current to 0, and then only introducing reverse current, namely-30 mA, at this time, the magnetic domain wall is perpendicular to the current direction and is positioned at the positions of 3 and 4, at this time, only the magnetic domain B of the first magnetic layer exists 1 (ii) a Finally, 30mA of forward current is applied, and only the magnetic domain B2 of the second magnetic layer exists, namely the magnetic domain B 1 Fully turned over to magnetic domain B 2 . When the reverse current of 30mA is continuously applied, the magnetic domain B is realized 2 Fully turned over to magnetic domain B 1 。
In one embodiment of the present invention, steps 102-103 include:
steps 102-103 are torsion-suppressing, dominated by rigid motion. We drop the magnetic field to 0, which is dominated by the rigid mode of motion, and then apply a reverse current to push the right end of the domain wall from position 2 to position 4. It is noted here that the domain wall has its left end already at position 3, which is the boundary of the device, and further down the device increases in size and reduces the current density so that the domain wall can only move to position 3 and cannot move further down. When we achieve a domain wall perpendicular to the current direction, i.e. between positions 3 and 4, the domain wall can be pushed by the current to achieve zero field switching according to the experimental results of figure 3 (c).
The embodiment of the invention provides a storage element, which comprises an antiferromagnetic film, wherein an antiferromagnetic film structure comprises a first magnetic layer, a non-magnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of magnetic moment in the first magnetic layer is antiparallel to the direction of magnetic moment in the second magnetic layer;
and the driving module is electrically connected with the antiferromagnetic film and is used for controlling the antiferromagnetic film to execute the method.
The method for regulating and controlling the magnetic domain flipping in the antiferromagnetic structure by using the current is described in detail in the embodiments of the present application, and the principle and the implementation of the present application are explained by applying specific examples, and the description of the embodiments is only used for helping to understand the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims (10)

1. A method for regulating domain switching in an antiferromagnetic structure using a current, comprising:
providing an antiferromagnetic film, wherein the antiferromagnetic film structure comprises a first magnetic layer, a nonmagnetic metal layer and a second magnetic layer which are sequentially stacked, and the direction of the magnetic moment in the first magnetic layer is antiparallel to the direction of the magnetic moment in the second magnetic layer;
applying a magnetic field and a first direction current to induce a magnetic domain wall, wherein the magnetic domain wall is positioned at a diagonal position of the antiferromagnetic film;
withdrawing the magnetic field and the first direction current, and applying a second direction current, wherein the magnetic domain wall is perpendicular to the second direction current;
applying a third direction current along which the domain wall translates, the magnetic domains in the first magnetic layer and the second magnetic layer completely flipping;
wherein the first direction current is opposite to the second direction current, and the first direction current is the same as the third direction current.
2. The method of claim 1, wherein the first magnetic layer and the second magnetic layer are both Co/Pt multilayer film structures; the first magnetic layer and the second magnetic layer are both perpendicular magnetic layers, and the first magnetic layer and the second magnetic layer are in a ferromagnetic exchange-coupled state.
3. The method of claim 1, wherein the nonmagnetic metal layer is a nonmagnetic Ru layer.
4. The method according to claim 1, wherein the non-magnetic metal layer is 1.25-1.35nm thick.
5. The method of claim 1, wherein applying the magnetic field and the first direction current induces a domain wall at a diagonal position of the antiferromagnetic film comprises:
the proportion of the magnetic domains in the first magnetic layer and the second magnetic layer on two sides of the magnetic domain wall is 45-55%.
6. The method of claim 1, wherein applying the magnetic field and the first direction current induces a domain wall at a diagonal position of the antiferromagnetic film comprises:
the magnetic field intensity is 60mT; the first direction current intensity is 30mA, and the first direction current is parallel to the antiferromagnetic film.
7. The method of claim 1, wherein withdrawing the magnetic field and the first direction current, applying a second direction current, the domain wall perpendicular to the second direction current, specifically comprises:
reducing the magnetic field to 0mT and the first direction current to 0mA;
a second direction current is applied with a strength of 30mA and opposite to the first direction current, so that the magnetic domain walls are moved perpendicular to the second direction current.
8. The method of claim 1, wherein applying a third direction current along which the domain wall translates and the magnetic domains in the first magnetic layer and the second magnetic layer fully switch comprises:
the intensity of the current in the third direction is 30mA, and the current in the third direction is the same as the current in the first direction.
9. The method of claim 1, wherein applying a third direction current along which the domain wall translates and the magnetic domains in the first magnetic layer and the second magnetic layer fully switch comprises:
and the complete turning is that the magnetic domains in the first magnetic layer are all turned into the magnetic domains in the second magnetic layer, or the complete turning is that the magnetic domains in the second magnetic layer are all turned into the magnetic domains in the first magnetic layer.
10. A memory element, comprising:
the anti-ferromagnetic thin film structure comprises a first magnetic layer, a non-magnetic metal layer and a second magnetic layer which are sequentially stacked, wherein the direction of the magnetic moment in the first magnetic layer is antiparallel to the direction of the magnetic moment in the second magnetic layer;
a driving module electrically connected to the antiferromagnetic film, the driving module being configured to control the antiferromagnetic film to perform the method of any one of claims 1-9.
CN202210759424.0A 2022-06-29 2022-06-29 Method for regulating and controlling magnetic domain overturning in antiferromagnetic structure by using current Pending CN115171747A (en)

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