CN110335940A - Giant magnetoresistance device and magnetic tunnel junction structure and electronic equipment including same - Google Patents

Abstract

The invention relates to a giant magnetoresistance device and a magnetic tunnel junction structure and electronic equipment including the same. According to an exemplary embodiment, a giant magnetoresistive device may include: a first reference magnetic layer having a fixed first in-plane magnetic moment; a free magnetic layer having a first a second in-plane magnetic moment reversible in substantially parallel and antiparallel directions; a first spacer layer located between said first reference magnetic layer and said free magnetic layer, and made of a non-magnetic metallic material forming; and a first electrode and a second electrode disposed on opposite sides of the first reference magnetic layer, the free magnetic layer and the first spacer layer for applying an in-plane current flowing therethrough, wherein the first The direction of the in-plane current applied by the first electrode and the second electrode forms an angle with the direction of the first in-plane magnetic moment of the first reference magnetic layer, and the angle is in the range of 30 degrees to 150 degrees.

Description

Giant magnetoresistance device and magnetic tunnel junction structure and electronic equipment including same

technical field

The present invention generally relates to the field of spintronics, and more particularly, relates to a giant magnetoresistance device and a magnetic tunnel junction structure, and electronic equipment including them.

Background technique

Giant magnetoresistance (GMR) devices and magnetic tunnel junction (MTJ) devices have been widely used in modern electronic devices, such as magnetic memories, spin logic devices, magnetic sensors, etc. Typical giant magnetoresistance (GMR) devices and magnetic tunnel junction (MTJ) devices have a sandwich structure, including a free magnetic layer, a reference magnetic layer, and a spacer layer between them. The spacer layer of a GMR device consists of a nonmagnetic Conductive metals such as Cu, Ru, etc. are formed, while the spacer layer of the MTJ device is formed of non _- magnetic insulating materials such as MgO, _Al2O3 , etc. The magnetic moment of the free magnetic layer can be flipped freely, while the magnetic moment of the reference magnetic layer is fixed, the resistance of the GMR and MTJ devices and the cosine value cos of the angle θ between the magnetic moments of the free magnetic layer and the magnetic moments of the reference magnetic layer (θ) is proportional. When the magnetic moment of the free magnetic layer and the magnetic moment of the reference magnetic layer are arranged parallel to each other, the resistance of the magnetic tunnel junction is the lowest, and it is in a low resistance state; when the magnetic moment of the free magnetic layer is arranged antiparallel to the magnetic moment of the reference magnetic layer, The magnetic tunnel junction has the highest resistance and is in a high resistance state.

How to flip the magnetic moment of the free magnetic layer of the magnetic tunnel junction has always been an important problem in the field of magnetic tunnel junction research, and it is also a problem that must be solved when the magnetic tunnel junction is applied to magnetic devices. The first method is to flip the magnetic moment of the free magnetic layer by two orthogonal magnetic fields, but this method needs to apply a large current to generate a large enough magnetic field, so the power consumption is large, and the magnetic field may affect adjacent devices , causing reliability problems. The second approach is to use spin-transfer torque (STT) to flip through a spin current flowing through a magnetic tunnel junction. However, this method also has certain drawbacks. If the spin current is too large, it is easy to cause the breakdown of the magnetic tunnel junction; if the spin current is too small, it is not enough to flip the magnetic moment of the free magnetic layer. Therefore, this method has very high requirements on the accuracy of the switching current and the uniformity of the magnetic tunnel junction array, making it difficult to be practical. The third approach is to use the spin Hall effect (SHE), which is also known as the spin-orbit torque (SOT) flipping scheme. For example, the granted Chinese invention patent 201510574526.5 proposes setting a spin Hall effect (SHE) layer in contact with the free magnetic layer, which can be formed of noble metals such as Pt, Au, Ta, etc. When an in-plane current flows through the SHE layer, the resulting spin current is injected into the adjacent free layer, thereby flipping the magnetic moment of the free layer. However, this method still needs to add a separate SHE layer, resulting in complex structures and fabrication processes.

Therefore, there is still a need for an improved method, which can realize the magnetic moment switching process with simple operation, stable operation and low power consumption.

Contents of the invention

In view of the above technical problems, the present invention is proposed.

According to an exemplary embodiment, a giant magnetoresistance (GMR) device is provided, comprising: a first reference magnetic layer having a fixed first in-plane magnetic moment; a free magnetic layer having a magnetic A second in-plane magnetic moment switchable in directions substantially parallel and antiparallel to the first in-plane magnetic moment of the layer; a first spacer layer positioned between said first reference magnetic layer and said free magnetic layer, and composed of formed of a non-magnetic metal material; and a first electrode and a second electrode disposed on opposite sides of the first reference magnetic layer, the free magnetic layer and the first spacer layer for applying an in-plane current flowing through them, wherein The direction of the in-plane current applied by the first electrode and the second electrode forms an angle with the direction of the first in-plane magnetic moment of the first reference magnetic layer, and the angle is in the range of 30 degrees to 150 degrees.

In some examples, the angle is about 90 degrees.

In some examples, the first reference magnetic layer is formed of a ferromagnetic material that, when applied with the in-plane current, generates a spin current through an anomalous Hall effect to flip the free magnetic layer magnetic moment.

In some examples, the GMR device further includes: a first pinning layer, formed of an antiferromagnetic material, located on the opposite side of the first reference magnetic layer to the first spacer layer, for pinning A first in-plane magnetic moment of the first reference magnetic layer.

In some examples, the first electrode and the second electrode are used to apply a write current, and the second in-plane magnetic moment of the free magnetic layer is reversed according to the direction of the write current.

In some examples, the first electrode and the second electrode are also used to apply a read current, the read current is smaller than the write current, so as not to make the second plane of the free magnetic layer The magnetic moment flips.

In some examples, the GMR device further includes: a third electrode and a fourth electrode, arranged on the upper and lower sides of the first reference magnetic layer, the free magnetic layer and the first spacer layer, for applying the current flowing through them. Vertical read current.

According to another exemplary embodiment, there is provided a magnetic tunnel junction structure, comprising: the above-mentioned GMR device; a second spacer layer, formed of a non-magnetic insulating material, located on the opposite side of the free magnetic layer to the first spacer layer one side; and a second reference magnetic layer, located on the opposite side of the second spacer layer from the free magnetic layer, having a third plane parallel to the first in-plane magnetic moment of the first reference magnetic layer internal magnetic moment.

In some examples, the magnetic tunnel junction structure further includes: a third electrode and a fourth electrode, arranged on the upper and lower sides of the magnetic tunnel junction structure, for applying a vertical current flowing through the magnetic tunnel junction structure, Wherein, the in-plane current applied by the first electrode and the second electrode is a write current, and the vertical current applied by the third electrode and the fourth electrode is a read current.

In some examples, the magnetic tunnel junction structure further includes: a second pinning layer formed of an antiferromagnetic material, located on the opposite side of the second reference magnetic layer to the second spacer layer, for A third in-plane magnetic moment of the second reference magnetic layer is pinned.

According to another exemplary embodiment, there is provided an electronic device including the above-mentioned giant magnetoresistive device or the above-mentioned magnetic tunnel junction structure.

In some examples, the electronic device is a magnetic memory device, a magnetic logic device, or a magnetic sensor.

In the giant magnetoresistance device and the magnetic tunnel junction structure of the present invention, there is no need to add additional layers, and the magnetic moment of the free magnetic layer can be reversed by passing a current in the absence of an external magnetic field, thus achieving simple operation, The magnetic moment reversal process with stability and low power consumption has broad application prospects.

Description of drawings

Fig. 1 is a schematic structural diagram of a giant magnetoresistive device according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the flipping principle of the giant magnetoresistive device of FIG. 1 .

FIG. 3 is a graph showing resistance characteristics of the giant magnetoresistive device of FIG. 1 after a flipping current is applied.

FIG. 4 is a schematic diagram of a magnetic tunnel junction structure according to another exemplary embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention are described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a giant magnetoresistive device according to an exemplary embodiment of the present invention. As shown in FIG. 1 , the giant magnetoresistive device 10 may include an antiferromagnetic pinning layer 11 , a reference magnetic layer 12 , a spacer layer 13 and a free magnetic layer 14 sequentially formed on a substrate (not shown). In some other embodiments, the antiferromagnetic pinning layer 11 , the reference magnetic layer 12 , the spacer layer 13 and the free magnetic layer 14 may be formed on the substrate in reverse order, which does not affect the implementation of the principles of the present invention.

The substrate may be any suitable substrate, such as Si substrate, SiO ₂ substrate, SOI substrate, quartz substrate, sapphire substrate, MgO substrate, Al ₂ O ₃ substrate and the like. In some embodiments, a buffer layer may also be formed on the substrate, and the antiferromagnetic pinning layer 11 is formed on the buffer layer.

The antiferromagnetic pinning layer 11 can be formed of an antiferromagnetic material such as IrMn, which is used to pin the magnetic moment of the reference magnetic layer 12 so that it can remain constant during the operation of the giant magnetoresistive device 10 .

Reference magnetic layer 12 and free magnetic layer 14 may each be formed of ferromagnetic materials such as Co, Fe, Ni, and alloys including Co, Fe, Ni, such as CoFe, NiFe, CoFeB, and the like. Each of the reference magnetic layer 12 and the free magnetic layer 14 has an in-plane magnetic moment, the magnetic moment of the reference magnetic layer 12 is pinned by the antiferromagnetic pinning layer 11 to keep fixed, and the magnetic moment of the free magnetic layer 14 can be It is free to flip in directions parallel and antiparallel to the magnetic moment of the reference magnetic layer 12 . Although in the embodiment of FIG. 1, the magnetic moment of the reference magnetic layer 12 is pinned by the antiferromagnetic pinning layer 11, in other embodiments, the reference magnetic layer 12 may also have a self-pinning structure, for example by having The magnetic moment of the reference magnetic layer 12 is kept fixed in a predetermined direction by using a larger thickness, using a hard magnetic material with a higher coercive force, or using an artificial antiferromagnetic structure, etc.

The spacer layer 13 is located between the reference magnetic layer 12 and the free magnetic layer 14 and is formed of non-magnetic and conductive materials, such as Cu, Ru, Au and the like.

It can be seen that the structure of the giant magnetoresistive device 10 described above is basically the same as the traditional giant magnetoresistive device, so it is only briefly described here to avoid making the description redundant and obscuring the gist of the present invention.

The giant magnetoresistive device 10 also includes a first electrode 15 and a second electrode 16 formed on opposite sides of the multilayer structure of the antiferromagnetic pinning layer 11, the reference magnetic layer 12, the spacer layer 13 and the free magnetic layer 14, Used to apply an in-plane current to the multilayer structure. In an embodiment of the present invention, the direction of the in-plane current applied through the first electrode 15 and the second electrode 16 forms an angle with the fixed magnetic moment direction of the reference magnetic layer 12, and the angle may be in the range of, for example, 30 degrees to 150 degrees , preferably within a range of 60° to 120°, more preferably within a range of 80° to 100°, for example, 90°. Since the magnetic moment of the free magnetic layer 14 is parallel or antiparallel to the magnetic moment of the reference magnetic layer 12, the direction of the in-plane current applied by the first electrode 15 and the second electrode 16 is also aligned with the magnetic moment direction of the free magnetic layer 14. angle.

The principle of switching the magnetic moment of the free magnetic layer 14 of the giant magnetoresistive device 10 will be described below with reference to FIG. 2 . As shown in FIG. 2 , the magnetic moment _mp of the reference magnetic layer 12 formed of NiFe may be in the +y-axis direction, and the magnetic moment m _f of the free magnetic layer 14 may be in the -y-axis direction, that is, the two are antiparallel to each other. The current I applied through the electrodes 15 and 16 is in the +x direction, that is, the angle between the current direction and the magnetic moment of the reference magnetic layer 12 is 90 degrees. When the in-plane current I in the +x direction flows through the giant magnetoresistive device 10, due to the anomalous Hall effect of the ferromagnetic material, the reference magnetic layer 12 will generate a spin current whose spin polarization direction is perpendicular to the current direction, As shown by the small ball arrow in Figure 2, the spin current is transmitted along the direction perpendicular to the film surface, as shown by the dotted arrow in Figure 2, and then absorbed by the free magnetic layer 14, the resulting spin torque acts on For the magnetic moment m _f of the free magnetic layer 14 , when the spin current is large enough, the magnetic moment m _f of the free magnetic layer 14 can be reversed from the direction of the -y axis to the direction of the +y axis. On the contrary, if the direction of the current is changed, for example, the direction of the -x axis, the magnetic moment m _f of the free magnetic layer 14 can be reversed to the direction of the -y axis.

It can be understood here that the angle between the current direction and the magnetic moment of the reference magnetic layer 12 When is 90 degrees, the spin torque of the magnetic moment m _f applied to the free magnetic layer 14 is the largest, but Other angles are also possible. As long as there is an included angle between the current direction and the magnetic moment of the reference magnetic layer 12 , the spin current generated by the current can apply a spin torque to the magnetic moment m _f of the free magnetic layer 14 . Preferably, the angle In the range of, for example, 30 degrees to 150 degrees.

It can also be understood that when the current I flows through the free magnetic layer 14 , it will also generate a spin current affecting the reference magnetic layer 12 . Since the magnetic moment of the reference magnetic layer 12 is fixed and difficult to be flipped, and the magnetic moment of the free magnetic layer 14 is easy to flip freely, so in the competition between the free magnetic layer 14 and the reference magnetic layer 12, the magnetic moment of the free magnetic layer 14 The moment is flipped, while the magnetic moment of the reference magnetic layer 12 can remain unchanged.

As mentioned above, by controlling the direction of the current I, the magnetic moment of the free magnetic layer 14 can be reversed to the desired direction, so that the giant magnetoresistive device 10 is in a parallel state (low resistance state) or an antiparallel state (high resistance state). resistance state), this process is equivalent to writing “0” or “1” into the giant magnetoresistive device 10 . In addition, a read current smaller than the aforementioned write current I can be applied through the electrodes 15 and 16 to read the state of the giant magnetoresistive device 10 . Here, the read current can also be applied via the electrodes 15 and 16 , but it is relatively small so as not to cause a magnetic moment reversal of the free magnetic layer 14 . The giant magnetoresistive device 10 of the present invention does not require additional layers to flip the magnetic moment of the free magnetic layer 14, and can apply the write current and the read current through the same electrode, thereby having a simpler structure and enabling operation Simple, stable, and low power consumption magnetic moment switching process.

FIG. 3 is a graph showing resistance characteristics of the giant magnetoresistive device of FIG. 1 after a flipping current is applied. Firstly, a reversal current (or called writing current) is applied to the giant magnetoresistive device 10 , and then a smaller read current is applied to read the state of the giant magnetoresistive device 10 . As can be seen from the graph in Fig. 3, when a larger flipping current is applied, the state of the giant magnetoresistive device 10 can be changed, and the direction of the flipping current can determine the direction of the magnetic moment of the free magnetic layer 14, thus in high resistance state and low-impedance state switching. Utilizing this characteristic of the giant magnetoresistive device 10, it can be used in various electronic devices, such as magnetic memory devices, spin logic devices, and magnetic sensors used as magnetic recording read heads. The application of traditional giant magnetoresistive devices in these electronic devices is known, and it is only necessary to replace the traditional magnetoresistive devices with the giant magnetoresistive device 10 of the present invention, so the details of these electronic devices will not be described here. Concrete structure.

FIG. 4 is a schematic diagram of a magnetic tunnel junction structure according to another exemplary embodiment of the present invention. As shown in FIG. 4 , the magnetic tunnel junction structure 20 includes a second spacer layer 21 formed on the free magnetic layer 14 in addition to the giant magnetoresistive device 10 described above, and a second spacer layer 21 formed on the second spacer layer 21 The second reference magnetic layer 22 , and the second antiferromagnetic pinning layer 23 formed on the second reference magnetic layer 22 .

Different from the first spacer layer 13 , the second spacer layer 21 of the magnetic tunnel junction structure 20 may be formed of non-magnetic insulating material such as metal oxide, and its typical materials may include MgO, Al ₂ O ₃ and so on. The second reference magnetic layer 22 may be formed of a ferromagnetic material, such as Co, Fe, Ni, and alloys including Co, Fe, Ni, such as CoFe, NiFe, CoFeB, and the like. The magnetic moment of the second reference magnetic layer 22 and the magnetic moment of the first reference magnetic layer 12 are parallel to each other, so that the magnetic moment of the free magnetic layer 14 can be parallel or opposite to both the first reference magnetic layer 12 and the second reference magnetic layer 22. parallel, so that the magnetic tunnel junction structure 20 can be in a low-resistance state or a high-resistance state.

The second antiferromagnetic pinning layer 23 can be similar to the antiferromagnetic pinning layer 11, formed of an antiferromagnetic material such as IrMn, etc., which is used to pin the magnetic moment of the second reference magnetic layer 22, so that it is in the magnetic tunnel The junction structure 20 may remain fixed during operation.

The magnetic tunnel junction structure 20 may also include a top electrode (third electrode) 24 and a bottom electrode (fourth electrode) 25, so as to apply a read current flowing vertically through the magnetic tunnel junction structure 20 to read the magnetic tunnel junction structure 20 state. The write current may be applied through the first electrode 15 and the second electrode 16 as described with reference to FIG. 1 .

Other embodiments of the present invention also provide an electronic device including the giant magnetoresistive device 10 or the magnetic tunnel junction structure 20 , such as a magnetic memory, a spin logic device, and a magnetic sensor used as a magnetic recording head. The application of traditional giant magnetoresistive devices and magnetic tunnel junction structures in these electronic devices is known, and it is only necessary to replace traditional devices with giant magnetoresistive devices 10 or magnetic tunnel junction structures 20 of the present invention, so it is not mentioned here The specific structure of these electronic devices will be described in detail.

The principles of the invention have been described above with reference to exemplary embodiments, and in these exemplary embodiments numerous details have been given, but it will be understood by those skilled in the art that the invention is not limited to these details. Rather, a person skilled in the art may practice the invention without these details, or with alternative details, and such embodiments shall fall within the scope of the invention. The scope of the invention is defined by the appended claims.

Claims (12)

1. A giant magnetoresistance (GMR) device, comprising: a first reference magnetic layer having a fixed first in-plane magnetic moment; a free magnetic layer having a second in-plane magnetic moment switchable in directions substantially parallel and antiparallel to the first in-plane magnetic moment of the first reference magnetic layer; a first spacer layer located between the first reference magnetic layer and the free magnetic layer and formed of a non-magnetic metallic material; and a first electrode and a second electrode disposed on opposite sides of the first reference magnetic layer, the free magnetic layer and the first spacer layer for applying an in-plane current flowing through them, Wherein, the direction of the in-plane current applied by the first electrode and the second electrode forms an angle with the direction of the first in-plane magnetic moment of the first reference magnetic layer, and the angle is in the range of 30 degrees to 150 degrees . 2. The GMR device of claim 1, wherein the angle is about 90 degrees. 3. The GMR device of claim 1, wherein the first reference magnetic layer is formed of a ferromagnetic material that, when the in-plane current is applied, generates spin by an anomalous Hall effect flow to flip the magnetic moment of the free magnetic layer. 4. The GMR device of claim 1, further comprising: A first pinning layer, formed of an antiferromagnetic material, located on the opposite side of the first reference magnetic layer to the first spacer layer, for pinning the first plane of the first reference magnetic layer magnetic moment. 5. The GMR device according to claim 1 , wherein the first electrode and the second electrode are used to apply a write current, and the second in-plane magnetic moment of the free magnetic layer depends on the write current direction is reversed. 6. The GMR device according to claim 5, wherein the first electrode and the second electrode are also used to apply a read current, the read current is smaller than the write current, so that the The second in-plane magnetic moment of the free magnetic layer is flipped. 7. The GMR device of claim 5, further comprising: The third electrode and the fourth electrode are arranged on the upper and lower sides of the first reference magnetic layer, the free magnetic layer and the first spacer layer, and are used for applying a vertical read current flowing through them. 8. A magnetic tunnel junction structure, comprising: The GMR device according to any one of claims 1-5; a second spacer layer formed of a non-magnetic insulating material on a side of the free magnetic layer opposite to the first spacer layer; and A second reference magnetic layer, on an opposite side of the second spacer layer from the free magnetic layer, has a third in-plane magnetic moment parallel to the first in-plane magnetic moment of the first reference magnetic layer. 9. The magnetic tunnel junction structure of claim 8, further comprising: The third electrode and the fourth electrode are arranged on the upper and lower sides of the magnetic tunnel junction structure, and are used to apply a vertical current flowing through the magnetic tunnel junction structure, Wherein, the in-plane current applied by the first electrode and the second electrode is a write current, and the vertical current applied by the third electrode and the fourth electrode is a read current. 10. The magnetic tunnel junction structure of claim 8, further comprising: A second pinning layer, formed of an antiferromagnetic material, located on the opposite side of the second reference magnetic layer to the second spacer layer, for pinning the third plane of the second reference magnetic layer magnetic moment. 11. An electronic device, comprising the giant magnetoresistive device according to any one of claims 1-7 or the magnetic tunnel junction structure according to any one of claims 8-10. 12. The electronic device of claim 11, wherein the electronic device is a magnetic memory device, a magnetic logic device, or a magnetic sensor.