JP7360121B2 - High-speed magnetization reversal method, high-speed magnetization reversal device, and magnetic memory device - Google Patents

Description

The present invention relates to a high-speed magnetization reversal method using spin-orbit torque, a high-speed magnetization reversal device, and a magnetic memory device.

A "spin injection magnetization reversal method" has been proposed as a method for controlling the reversal of magnetization of nano-sized magnetic materials, and has already been put into practical use in MRAM (Magnetic Random Access Memory) and the like. Early MRAMs wrote information by reversing the magnetization direction of the magnetic film of the MRAM element using a magnetic field created by an electric current, but as MRAM elements became smaller due to higher integration, a large current was required to reverse the magnetization. There was also an issue with power consumption. Here, in MRAM, the structure corresponding to one bit that stores information is composed of a three-layer structure of a first ferromagnetic metal, a nonmagnetic material, and a second ferromagnetic metal.

The "spin injection magnetization reversal method" that has improved this problem is based on the fact that when electrons flow from a ferromagnetic metal to a nonmagnetic material, the electron flow is "spin polarized." This is a technique in which the magnetic moment of the second ferromagnetic metal can be reversed by moving it from a ferromagnetic metal to a second ferromagnetic metal via a nonmagnetic material. Here, "spin polarization" means a state in which the number of spin-up electrons and the number of spin-down electrons are not the same, but are biased to one side.

The torque that reverses the magnetic moment of the second ferromagnetic metal by passing this spin-polarized current through the second ferromagnetic metal is called "spin transfer torque (STT)." This STT brings about magnetization reversal. According to MRAM (STT-RAM), which uses STT for magnetization reversal (information writing), magnetization can be reversed simply by passing a spin-polarized current, so even if the element is miniaturized, the current density becomes smaller, resulting in power savings. This has made it possible to increase the integration density of MRAM.

On the other hand, in order to process a large amount of recorded information at high speed as the density of magnetic memory increases, there is a need for faster access times for recording and reproducing magnetically recorded information. Increasing the speed in principle of magnetic resistance (magnetic resistance) is also a development issue. Further, as elements become smaller, the write current for magnetization reversal becomes larger during writing, resulting in a problem of higher power consumption.

In recent years, magnetization reversal methods have been developed using spin injection ("pure spin current") that does not involve current (net charge transfer) into ferromagnetic metals, rather than spin injection via spin-polarized current as in STT. A method based on the principle called "spin orbit torque" (SOT) has been proposed. Each electron flowing through a nonmagnetic metal has spin, which is responsible for magnetization. Because the spins of current flowing through non-magnetic metals are oriented in various directions, the net magnetization of current flowing through non-magnetic metals is zero. However, if the spin direction of the current is biased, the current has magnetization. In other words, the current becomes a flow of magnetization as well as charge. Such a flow of magnetization is called a spin current. In particular, a spin current in which the net flow of electrons is zero and there is no current, and only magnetization flows, is called a pure spin current.

When a current flows through a nonmagnetic metal with a large spin-orbit coupling, the direction of movement of the conduction electrons that make up the current is bent by the spin Hall effect caused by the spin-orbit interaction. The direction of this bending depends on the spin direction of the conduction electrons. In other words, the flow created by a group of electrons bent toward the ferromagnetic metal that is in contact with the nonmagnetic metal due to the current in the nonmagnetic metal becomes a spin current. Furthermore, the flow (spin current) that is bent in the direction of the ferromagnetic metal enters the ferromagnetic metal as it is. Therefore, in a laminated structure of a ferromagnetic metal and a nonmagnetic metal, when current flows through the nonmagnetic metal, conduction electron spins are injected from the nonmagnetic metal to the ferromagnetic metal. This is called spin injection. Since no potential difference occurs between the ferromagnetic metal and the nonmagnetic metal, the spin current is a pure spin current. The spins injected into the ferromagnetic metal are scattered within the ferromagnetic metal, imparting spin angular momentum to the magnetization of the ferromagnetic metal. As a result, the direction of magnetization of the ferromagnetic metal changes. The technology that utilizes this change to reverse the magnetization of ferromagnetic metal is called magnetization reversal using SOT, and a magnetic memory that uses this magnetization reversal to rewrite (write) information is called SOT-RAM.

Here, the amount by which spin is bent within a nonmagnetic metal is given by a physical quantity called the spin Hall angle. Further, the direction in which the spin is bent is perpendicular to the direction in which the electron is moving and the direction of the spin that the electron has. The greater the absolute value of the spin Hall angle of a nonmagnetic metal, the greater the amount by which the spins of electrons flowing through the nonmagnetic metal are bent. The larger the absolute value of the spin Hall angle of the nonmagnetic metal that is in contact with the ferromagnetic metal, the more spins are injected from the nonmagnetic metal into the ferromagnetic metal.

It includes a spin-orbit torque wiring configured to generate a spin current and induce SOT when a current flows, and a ferromagnetic metal layer disposed on the spin-orbit torque wiring. A configuration in which the direction of magnetization of a ferromagnetic metal layer is changed is known (Patent Document 1, Non-Patent Document 1).

Japanese Patent Application Publication No. 2019-9478 (published on January 17, 2019)

Shunsuke Fukami, Research on a new magnetization control method using spin-orbit torque and its application to 3-terminal magnetic memory devices, https://kaken.nii.ac.jp/ja/file/KAKENHI-PROJECT-15K13964/15K13964seika.pdf , Grants-in-Aid for Scientific Research Research Results Report June 12, 2017

In the conventional magnetization reversal technology in SOT-RAM as described above, spin is injected into the ferromagnetic metal by the spin Hall effect from a non-magnetic metal lead placed in contact with the ferromagnetic metal of the target. SOT works on magnetization. If the size of the SOT is sufficiently large, magnetization reversal is induced in the ferromagnetic metal, and the magnetization is reversed in the direction of the injected spin. In SOT, as the amount of spins injected into the ferromagnetic metal increases, the size of the SOT also increases. Further, the current flowing through the nonmagnetic metal lead and the amount of spin injected into the spin Hall angle in the nonmagnetic metal are proportional.

However, in practice, it is necessary to be able to reverse the magnetization of a ferromagnetic metal at high speed with a low current, and magnetization reversal at a low current has not been observed in magnetization reversal using a conventional SOT. Therefore, it is a challenge to clarify the configuration guidelines for elements that can reverse the magnetization of ferromagnetic metals at high speed with low current. One of the reasons why magnetization reversal does not occur due to low current SOT is that the initial change in magnetization of the ferromagnetic metal does not occur, and it is desired to construct an element that solves this problem. Magnetization reversal is made possible with low current by applying an external magnetic field and SOT to the ferromagnetic metal simultaneously during magnetization reversal, or by applying STT and SOT to the ferromagnetic metal simultaneously.

One aspect of the present invention aims to realize a high-speed magnetization reversal method, a high-speed magnetization reversal device, and a magnetic memory device that can reverse the magnetization of a ferromagnetic metal at high speed with low current using SOT.

In order to solve the above problems, a high-speed magnetization reversal method according to one embodiment of the present invention provides a method for magnetization of a ferromagnetic metal layer in a metal layer structure in which one or two non-magnetic metal layers and a ferromagnetic metal layer are laminated. This is a high-speed magnetization reversal method in which the ferromagnetic metal layer is given uniaxial magnetic anisotropy in advance so that a specific direction is the axis of easy magnetization, and the magnetization of the ferromagnetic metal layer is reversed by spin-orbit torque. A spin injection magnetization reversal process in which a reversal spin current is injected from a nonmagnetic metal layer to a ferromagnetic metal layer in order to induce magnetization reversal on the easy axis, and a ferromagnetic metal thin film from the same or another nonmagnetic metal layer. The method includes an auxiliary spin current injection step in which an auxiliary spin current is injected into the ferromagnetic metal layer for a short period of time. It is characterized by being injected at different times.

According to this feature, a spin current (auxiliary spin current) magnetized in a direction crossing the magnetization direction (first direction) of the ferromagnetic metal layer is injected into the ferromagnetic metal thin film. Therefore, the process of reversing the magnetization direction of the ferromagnetic metal thin film due to the reversal spin current magnetized in the opposite direction to the first direction (spin injection magnetization reversal process) is caused by the reversal process of the magnetization direction of the ferromagnetic metal thin film due to the reverse spin current magnetized in the opposite direction to the first direction. This is assisted by a step of injecting a spin current (auxiliary spin injection step).

The auxiliary spin current is injected into the ferromagnetic metal thin film for only a short period of time. The reversal spin current is injected into the ferromagnetic metal thin film during the entire time during magnetization reversal, and the auxiliary spin current is injected while the spin current is injected into the ferromagnetic metal layer. Alternatively, during or immediately after the injection of the auxiliary spin current, the reversal spin current begins to be injected into the ferromagnetic metal thin film, and is injected until before or after the magnetization reversal ends. If the reverse spin current is injected until half or more of the magnetization reversal occurs, the magnetization reversal will occur even if the reverse spin current is stopped before the magnetization reversal is completed. However, in that case, the faster the time to stop the reversed spin current, the longer the time required for reversal. Further, even after the magnetization reversal is completed, the reversal spin current may be continued to be injected, but this results in wasted power consumption.

As a result, the magnetization direction of the ferromagnetic metal can be reversed at high speed or with low power consumption.

In order to solve the above problems, in a fast magnetization reversal method according to one embodiment of the present invention, one or two nonmagnetic metal layers are one nonmagnetic metal layer,
Preferably, the auxiliary spin current injection step injects the auxiliary spin current from the same nonmagnetic metal layer.

According to the above configuration, the configuration for injecting the auxiliary spin current from the nonmagnetic metal layer becomes simple.

In order to solve the above problems, in a fast magnetization reversal method according to one embodiment of the present invention, one or two nonmagnetic metal layers are two nonmagnetic metal layers,
Preferably, the auxiliary spin current injection step injects the auxiliary spin current from another non-magnetic metal layer.

According to the above structure, it is possible to increase the variation of the structure in which the auxiliary spin current is injected from the nonmagnetic metal layer.

In order to solve the above problems, in the fast magnetization reversal method according to one embodiment of the present invention, the spin injection magnetization reversal step is performed at an appropriate timing after the auxiliary spin current injection step is performed in addition to the spin injection magnetization reversal step. Preferably, the reversal spin current of is injected into the ferromagnetic metal layer during the entire time during magnetization reversal, and the auxiliary spin current is injected while the reversal spin current is injected into the ferromagnetic metal layer.

According to the above configuration, the reversal of the magnetization direction of the ferromagnetic metal layer by the spin current is assisted by the auxiliary spin current injected while the spin current is injected into the ferromagnetic metal layer throughout the entire time during magnetization reversal. Ru.

In order to solve the above problems, in the fast magnetization reversal method according to one embodiment of the present invention, it is preferable that the auxiliary spin current starts to be injected into the ferromagnetic metal layer immediately after or simultaneously with the start of the spin injection magnetization reversal step. .

According to the above configuration, the auxiliary spin current that is started to be injected into the ferromagnetic metal layer immediately after or simultaneously with the start of the spin injection magnetization reversal step assists in reversing the magnetization direction of the ferromagnetic metal layer by the spin current.

In order to solve the above problems, in the fast magnetization reversal method according to one aspect of the present invention, it is preferable that the auxiliary spin current starts to be injected into the ferromagnetic metal layer immediately before the start of the spin injection magnetization reversal step.

According to the above configuration, the auxiliary spin current that starts to be injected into the ferromagnetic metal layer immediately before the start of the spin injection magnetization reversal process assists the reversal of the magnetization direction of the ferromagnetic metal layer by the spin current.

In order to solve the above problems, in the spin injection magnetization reversal step of the high-speed magnetization reversal method according to one embodiment of the present invention, a direction parallel to the easy axis of magnetization of the ferromagnetic metal layer is transferred from the nonmagnetic metal layer to the ferromagnetic metal layer. Preferably, a reversed spin current with a magnetization orientation in the direction is injected.

According to the above configuration, an inverted spin current can be injected into the ferromagnetic metal layer through the main lead layer extending in a direction perpendicular to the easy axis direction of the ferromagnetic metal layer.

In order to solve the above problems, in a high-speed magnetization reversal method according to one aspect of the present invention, it is preferable that the nonmagnetic metal layer includes a main lead layer extending in a direction perpendicular to the axis of easy magnetization.

According to the above configuration, a current flowing in a direction parallel to the main lead layer is caused to flow through the non-magnetic metal layer through the main lead layer, thereby magnetizing the ferromagnetic metal layer from the non-magnetic metal layer to the ferromagnetic metal layer. It is possible to inject a reversed spin current with a magnetization direction parallel to the easy axis direction.

In order to solve the above problems, in a fast magnetization reversal method according to one embodiment of the present invention, the main lead layer is made of the same material as the nonmagnetic metal layer, metal, or other material with low electrical resistance. It is preferable.

According to the above structure, the main lead layer can be realized with a simple structure.

In order to solve the above problems, in the auxiliary spin current injection step of the fast magnetization reversal method according to one embodiment of the present invention, a strong It is preferable that an auxiliary spin current having a magnetization direction perpendicular to the easy axis direction of the magnetic metal layer is injected.

According to the above configuration, an auxiliary spin current can be injected into the ferromagnetic metal layer through the auxiliary lead layer extending in a direction parallel to the easy axis of magnetization of the ferromagnetic metal layer.

In order to solve the above problems, in a high-speed magnetization reversal method according to one embodiment of the present invention, either a non-magnetic metal layer or another non-magnetic metal layer is It is preferable to include an auxiliary lead layer extending in parallel directions.

According to the above configuration, a current flowing in a direction parallel to the auxiliary lead layer extending in a direction parallel to the easy axis direction of magnetization of the ferromagnetic metal layer is passed through the auxiliary lead layer to another nonmagnetic metal layer. By doing so, it is possible to inject an auxiliary spin current having a magnetization direction perpendicular to the easy axis direction of the ferromagnetic metal layer from another nonmagnetic metal layer to the ferromagnetic metal layer.

In order to solve the above problems, in a fast magnetization reversal method according to one embodiment of the present invention, in the auxiliary spin current injection step, a spin current is transferred from another nonmagnetic metal layer to a ferromagnetic metal layer in the direction of the easy axis of magnetization of the ferromagnetic metal layer. It is preferable that an auxiliary spin current having a magnetization direction perpendicular to the direction is injected.

According to the above configuration, by flowing an auxiliary spin current having a direction of magnetization perpendicular to the easy axis direction of the ferromagnetic metal layer to another non-magnetic metal layer, ferromagnetic An auxiliary spin current having a magnetization direction perpendicular to the easy axis direction of the ferromagnetic metal layer can be injected into the metal layer.

In order to solve the above problems, in a fast magnetization reversal method according to one embodiment of the present invention, another non-magnetic metal layer has a direction perpendicular to the easy axis direction of magnetization of the ferromagnetic metal layer, and , it is preferable to include an auxiliary lead layer extending in a direction perpendicular to the injection direction of the reversed spin current.

According to the above configuration, the direction is perpendicular to the easy axis direction of magnetization of the ferromagnetic metal layer, and parallel to the auxiliary lead layer extending in the direction perpendicular to the injection direction of the reversed spin current. By passing a current flowing through the auxiliary lead layer to another non-magnetic metal layer, magnetization is generated from the other non-magnetic metal layer to the ferromagnetic metal layer in a direction perpendicular to the easy axis of magnetization of the ferromagnetic metal layer. An auxiliary spin current with the orientation can be injected.

In order to solve the above problems, in a high-speed magnetization reversal method according to one embodiment of the present invention, a non-magnetic metal layer and another non-magnetic metal layer are brought into contact with the main surface or side surface of a ferromagnetic metal layer to Preferably, it is bonded to a metal layer.

According to the above configuration, an inverted spin current can be injected into the ferromagnetic metal layer through the nonmagnetic metal layer that is in contact with the main surface or side surface of the ferromagnetic metal layer and bonded to the ferromagnetic metal layer, and An auxiliary spin current can be injected into the ferromagnetic metal layer through another non-magnetic metal layer that is joined to the ferromagnetic metal layer against the main or side surface of the layer.

In order to solve the above problems, a fast magnetization reversal device according to one embodiment of the present invention has a metal layer structure in which one or two nonmagnetic metal layers and a ferromagnetic metal layer are laminated. A high-speed magnetization reversal method in which magnetization is reversed by spin-orbit torque, wherein the ferromagnetic metal layer is given uniaxial magnetic anisotropy in advance so that a specific direction becomes an axis of easy magnetization, and the ferromagnetic metal layer a spin injection magnetization reversal step of injecting a reversal spin current from the nonmagnetic metal layer to the ferromagnetic metal layer in order to induce magnetization reversal on the easy axis of magnetization of the layer; and an auxiliary spin current injection step of injecting an auxiliary spin current from the metal layer into the ferromagnetic metal layer for a short time, the reversed spin current and the auxiliary spin current having different magnetization directions of the spin currents. The method is characterized in that two types of spin currents are injected into the ferromagnetic metal layer at different times.

According to this feature, the magnetization direction of the ferromagnetic metal can be reversed at high speed or with low power consumption.

In order to solve the above problems, in a fast magnetization reversal device according to one embodiment of the present invention, the ferromagnetic metal layer is made of a NiFe-based binary alloy, a CoFeB alloy, or has a finite spin polarization near room temperature. Preferably, at least one of the nonmagnetic metal layer and the other nonmagnetic metal layer contains at least one of Pt, Ru, and other metals having a large absolute value of the spin Hall angle.

According to the above configuration, the material of the ferromagnetic metal layer, the material of the nonmagnetic metal layer of the main lead layer, and the material of the nonmagnetic metal layer of the auxiliary lead layer cause ferromagnetism based on the spin Hall effect due to spin-orbit interaction. The spin-orbit torque acting on the metal thin film increases.

In order to solve the above problems, a fast magnetization reversal device according to one embodiment of the present invention includes an insulating layer stacked on a ferromagnetic metal layer, and a magnetization layer stacked on the insulating layer in the direction of the easy axis of magnetization. A magnetized pinned layer, a readout lead wire bonded to the pinned layer for reading out the magnetization direction of the ferromagnetic metal layer, a current supply to the non-magnetic metal layer for reversal spin current, and an auxiliary spin current. It is preferable that the ferromagnetic metal layer further includes a control circuit that controls the supply of current to another non-magnetic metal layer and the reading of the magnetization direction of the ferromagnetic metal layer from a read lead wire.

According to the above configuration, the supply of reversal current to the main lead layer, the supply of auxiliary current to the auxiliary lead layer, and the readout of the magnetization direction of the ferromagnetic metal thin film from the readout lead wire are controlled, and the magnetization is quickly reversed. It becomes possible to write and read information to and from the device.

In order to solve the above problems, a magnetic memory device according to one embodiment of the present invention includes a plurality of tunnel magnetoresistive elements arranged in a matrix, and the tunnel magnetoresistive element has a fixed layer and a free layer. and an insulating layer formed between the pinned layer and the free layer, for injecting into the free layer an inverted spin current magnetized in an inverted direction opposite to the first direction corresponding to the easy axis of magnetization of the free layer. , a plurality of inverted lead wires extending along a cross direction intersecting the first direction and joining each free layer; A plurality of auxiliary lead wires are extended along the first direction or the cross direction and are joined to each fixed layer in order to read out the magnetization direction of each free layer. It is characterized by comprising a plurality of readout lead wires.

According to one aspect of the present invention, the magnetization of a ferromagnetic metal can be reversed quickly with low current.

(a) is a perspective view of a high-speed magnetization reversal device according to Embodiment 1, (b) is a plan view thereof, and (c) is a front view thereof. (a) is a perspective view of another high-speed magnetization reversal device according to Embodiment 1, (b) is a plan view thereof, and (c) is a front view thereof. (a) is a perspective view of yet another high-speed magnetization reversal device according to Embodiment 1, (b) is a plan view thereof, and (c) is a front view thereof. FIG. 3 is a diagram showing simulation results of the magnetization reversal time of the ferromagnetic metal thin film provided in the high-speed magnetization reversal device. 3 is a graph showing the relationship between spin injection time and magnetization of the above-mentioned fast magnetization reversal device. (a) is a graph showing the relationship between the auxiliary spin current of the ferromagnetic metal thin film and the time required for magnetization reversal of the ferromagnetic metal thin film, and (b) is a graph showing the relationship between the ferromagnetic metal thin film and the reversal lead. (c) is a perspective view showing the ferromagnetic metal thin film, the reversal lead wire, and the auxiliary lead wire. (a) is a perspective view showing the magnetization direction of a ferromagnetic metal thin film according to a comparative example, and (b) to (e) are perspective views showing the relationship between the ferromagnetic metal thin film and the reversal lead wire. f) is a perspective view showing another magnetization direction of the ferromagnetic metal thin film, (g) to (j) are perspective views showing the relationship between the ferromagnetic metal thin film and the reversal lead wire, and (k) is a perspective view showing still another magnetization direction of the ferromagnetic metal thin film, and (l) to (o) are perspective views showing the relationship between the ferromagnetic metal thin film and the reversal lead wire. (a) is a perspective view showing the relationship between the ferromagnetic metal thin film and the reversal lead wire provided in the high-speed magnetization reversal device, and (b) to (i) are auxiliary views for the ferromagnetic metal thin film and the reversal lead wire. FIG. 3 is a perspective view showing various arrangement modes of lead wires. (a) is a perspective view showing an embodiment of the ferromagnetic metal thin film, and (b) is a perspective view showing another embodiment of the ferromagnetic metal thin film. (a) is a perspective view of an experimental apparatus for a fast magnetization reversal device according to Embodiment 2, (b) is a perspective view of the fast magnetization reversal device, and (c) is a circuit diagram of the fast magnetization reversal device. be. 3 is a schematic plan view of a magnetic memory device according to Embodiment 2. FIG. 7 is a circuit diagram related to a write operation of the magnetic memory device according to Embodiment 2. FIG. 5 is a flowchart showing a write operation of the magnetic memory device. (a) is a circuit diagram including parts related to the read operation of the magnetic memory device according to the second embodiment, and (b) is a perspective view showing a TMR element of the magnetic memory device. FIG. 7 is a circuit diagram related to a modification of the write operation of the magnetic memory device.

Hereinafter, one embodiment of the present invention will be described in detail.

[Embodiment 1]
FIG. 1(a) is a perspective view of a high-speed magnetization reversal device 1 according to Embodiment 1, FIG. 1(b) is a plan view thereof, and FIG. 1(c) is a front view thereof.

The high-speed magnetization reversal device 1 includes a ferromagnetic metal thin film 2 (ferromagnetic metal layer) magnetized in the y direction (first direction) corresponding to the easy axis of magnetization, and a device for reversing the magnetization direction of the ferromagnetic metal thin film 2. , a reversal lead wire 3 (non-magnetic metal layer, main lead layer) for injecting a reversal spin current magnetized in the -y direction (reversal direction) into the ferromagnetic metal thin film 2, and a magnetization direction of the ferromagnetic metal thin film 2. An auxiliary lead wire 4 (non-magnetic metal layer, auxiliary lead layer ). The ferromagnetic metal thin film 2 is given uniaxial magnetic anisotropy in advance so that the y direction is the axis of easy magnetization.

The reversal lead wire 3 is composed of a nonmagnetic metal layer extending in the x direction. The auxiliary lead wire 4 is composed of a nonmagnetic metal layer extending in the y direction. The inversion lead wire 3 and the auxiliary lead wire 4 intersect with each other at the point where they are joined to the ferromagnetic metal thin film 2, and are integrally formed of the same nonmagnetic metal layer.

In this way, the auxiliary lead wire 4 for injecting the auxiliary spin current into the ferromagnetic metal thin film 2 extends in a direction parallel to or perpendicular to the axis of easy magnetization of the ferromagnetic metal thin film 2. The reversal lead wire 3 for injecting the reversal spin current into the ferromagnetic metal thin film 2 extends in a direction perpendicular to the axis of easy magnetization. The auxiliary spin current has a magnetization direction perpendicular to the easy axis direction of magnetization of the ferromagnetic metal thin film 2. The reversed spin current has a magnetization direction parallel to the easy axis direction of the ferromagnetic metal thin film 2.

The ferromagnetic metal thin film 2 includes a NiFe-based binary alloy (permalloy), a CoFeB alloy, and other ferromagnetic materials that have a finite spin polarization near room temperature. At least one of the inversion lead wire 3 and the auxiliary lead wire 4 includes at least one of Pt, Ru, and other metals having a large absolute value of the spin Hall angle.

The thus configured high-speed magnetization reversal device 1 operates as follows.

First, in order to reverse the magnetization direction of the ferromagnetic metal thin film 2 magnetized in the y direction, a reversal current for injecting a reversal spin current magnetized in the -y direction into the ferromagnetic metal thin film 2 is applied to the reversal lead wire 3. supplied to In order to assist in reversing the magnetization direction of the ferromagnetic metal thin film 2, an auxiliary spin current magnetized in the x direction (cross direction) orthogonal to the y direction is supplied to the ferromagnetic metal thin film 2 from the auxiliary lead wire 4. Ru. Next, a reversed spin current based on the reversed current supplied to the reversed lead wire 3 is injected from the reversed lead wire 3 into the ferromagnetic metal thin film 2 based on the spin Hall effect due to spin-orbit interaction. Then, an auxiliary spin current based on the auxiliary current supplied to the auxiliary lead wire 4 is injected from the auxiliary lead wire 4 into the ferromagnetic metal thin film 2 based on the spin Hall effect due to spin-orbit interaction.

After that, the magnetization direction of the ferromagnetic metal thin film 2 in the y direction is magnetized in the -y direction and injected into the ferromagnetic metal thin film 2 from the reversal lead wire 3, and the ferromagnetic metal thin film 2 is magnetized in the x direction and is injected into the auxiliary lead wire. The auxiliary spin current injected into the ferromagnetic metal thin film 2 from the ferromagnetic metal thin film 2 causes the spin to reverse from the y direction to the -y direction at high speed.

In this way, by injecting two types of reversal spin currents and auxiliary spin currents magnetized in different directions into the ferromagnetic metal thin film 2 from the same nonmagnetic metal layer, the magnetization reversal of the ferromagnetic metal thin film 2 is made easier. The magnetization of the ferromagnetic metal thin film 2 can be reversed at high speed in about 10% of the time compared to the conventional technique of injecting one type of spin current from one direction.

In addition, in the embodiment described above, an example was shown in which the magnetization direction of the reverse spin current and the magnetization direction of the auxiliary spin current are orthogonal to each other, but the present invention is not limited to this. The magnetization direction of the reversal spin current and the magnetization direction of the auxiliary spin current only need to be different from each other, and the angle between them only needs to be larger than 0 degrees and smaller than 180 degrees. The same applies to the embodiments described later.

FIG. 2(a) is a perspective view of another high-speed magnetization reversal device 1A according to Embodiment 1, FIG. 2(b) is a plan view thereof, and FIG. 2(c) is a front view thereof. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

The difference from the high speed magnetization reversal device 1 described above with reference to FIG. In this way, the reversal lead wire 3 and the auxiliary lead wire 4 are joined to the ferromagnetic metal thin film 2 at different locations, and are constructed separately from mutually different nonmagnetic metal layers.

According to this configuration, in order to reverse the magnetization direction of the ferromagnetic metal thin film 2 magnetized in the y direction, a reversal spin current magnetized in the -y direction is used to assist in reversing the magnetization direction of the ferromagnetic metal thin film 2. Therefore, an auxiliary spin current magnetized in the x direction is injected into the ferromagnetic metal thin film 2 through two different opposing surfaces of the ferromagnetic metal thin film 2.

Then, the y The direction of magnetization is reversed at high speed in the -y direction.

FIG. 3(a) is a perspective view of yet another high-speed magnetization reversal device 1B according to Embodiment 1, FIG. 3(b) is a plan view thereof, and FIG. 3(c) is a front view thereof. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

The difference from the high-speed magnetization reversal device 1 described above in FIG. 1 is that the auxiliary lead wire 4 is joined to the side surface of the ferromagnetic metal thin film 2 parallel to the y direction. In this way, the reversal lead wire 3 and the auxiliary lead wire 4 are joined to the ferromagnetic metal thin film 2 at different locations, similar to the configuration shown in FIG. .

According to this configuration, an inverted spin current magnetized in the -y direction and an auxiliary spin current magnetized in the x direction are injected into the ferromagnetic metal thin film 2 through two different adjacent surfaces of the ferromagnetic metal thin film 2. be done. Then, due to the reversal spin current and the auxiliary spin current, the magnetization direction of the ferromagnetic metal thin film 2 in the y direction is reversed to the −y direction at high speed.

FIG. 4 is a diagram showing simulation results of the magnetization reversal time of the ferromagnetic metal thin film 2 provided in the high-speed magnetization reversal device 1.

A ferromagnetic metal thin film by SOT when only a reversed spin current magnetized in the -y direction is injected into a ferromagnetic metal thin film 2 with dimensions of 30 nm x 30 nm x 7.5 nm without the support of magnetization reversal by an auxiliary spin current. The simulation result of the magnetization reversal time of No. 2 was 17 nsec. On the other hand, when the auxiliary spin current magnetized in the x direction is injected into the ferromagnetic metal thin film 2 in addition to the reversal spin current, the reversal time of the magnetization of the ferromagnetic metal thin film 2 is shortened to about 0.8 nsec. Ta.

FIG. 5 is a graph showing the relationship between spin injection time and magnetization reversal of the high-speed magnetization reversal device 1A. A simulation of high-speed magnetization reversal was performed under the condition that the ferromagnetic metal thin film 2 of the high-speed magnetization reversal device 1A described above in FIG. 2 was composed of permalloy with cell sizes of X=10 nm, Y=10 nm, and Z=20 nm.

In spin injection using only the reversed spin current of the reversed lead wire 3, the spin injection time until magnetization reversal was about 4 nsec, as shown by curve S1. On the other hand, the spin injection by the reversed spin current of the reversed lead wire 3 and the spin injection by the auxiliary spin current of the auxiliary lead wire 4 were combined, and the reversed spin current was injected immediately after the auxiliary spin current was injected for 0.1 nsec. In this case, as shown by curve S2, the spin injection time until magnetization reversal was shortened to about 1 nsec. Also, when the reversal spin current was injected immediately after the auxiliary spin current was injected for 2 nsec, the spin injection time until magnetization reversal was shortened to about 1 nsec, as shown by curve S3.

Note that spin injection using only the auxiliary spin current of the auxiliary lead wire 4 failed to cause magnetization reversal, as shown by curve S4.

FIG. 6(a) is a graph showing the relationship between the auxiliary spin current of the ferromagnetic metal thin film 2 and the time required for magnetization reversal of the ferromagnetic metal thin film 2, and FIG. FIG. 3C is a perspective view showing the ferromagnetic metal thin film 2, the inversion lead wire 3, and the auxiliary lead wire 4. FIG. A simulation of high-speed magnetization reversal was performed under the condition that the ferromagnetic metal thin film 2 of the high-speed magnetization reversal device 1 described above in FIG.

When a main write current (reversal current) with a current density of 3.0×10 ¹¹ A/m ² is applied only to the reversal lead wire 3, as shown at point P1 in FIG. The magnetization of the ferromagnetic metal thin film 2 was reversed. At the same time as the main write current was applied, a short-time current was applied to the auxiliary lead wire 4 for 1.0 ns, the application time of which was shorter than the main write current for auxiliary writing, to inject an auxiliary spin current into the ferromagnetic metal thin film 2. However, within the range of the simulation, the magnetization was reversed in 10 ns at the shortest, as shown at point P2.

When the main write current density and the auxiliary write current density are both equal at 3.0×10 ¹¹ A/m ² , the spin injection time using a short-time current for auxiliary writing is changed. At 1 ns, the magnetization was reversed at about 20 ns, as shown at point P3 in FIG. 6(a). When the spin injection time by the auxiliary write current was 0.1 ns, the magnetization was reversed in about 15 ns.

The magnetization reversal time of the ferromagnetic metal thin film 2 changes depending on the type, shape, and auxiliary write line of the ferromagnetic metal thin film 2 as the current density of the main write current and the current density of the short-time current for auxiliary writing increase. (Auxiliary lead wire 4) is shortened independently of its position. However, the spin injection time from the short-time current for auxiliary writing does not necessarily have to be long, but depends on the type and shape of the ferromagnetic metal thin film 2, the position of the auxiliary writing wire (auxiliary lead wire 4), etc. There is an optimal value.

FIG. 7(a) is a perspective view showing the magnetization direction of the ferromagnetic metal thin film 2 according to a comparative example, and (b) to (e) are perspective views showing the relationship between the ferromagnetic metal thin film 2 and the reversal lead wire 3. (f) is a perspective view showing another magnetization direction of the ferromagnetic metal thin film 2, and (g) to (j) are perspective views showing the relationship between the ferromagnetic metal thin film 2 and the reversal lead wire 3. (k) is a perspective view showing still another magnetization direction of the ferromagnetic metal thin film 2, and (l) to (o) are perspective views showing the relationship between the ferromagnetic metal thin film 2 and the reversal lead wire 3. be. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

FIG. 7 shows 12 types of patterns of the position and direction of the inversion lead wire 3 relative to the ferromagnetic metal thin film 2 related to unidirectional injection. The position and direction pattern of the reversing lead wire 3 with respect to the ferromagnetic metal thin film 2 for reversing the direction of magnetization in the z direction of the ferromagnetic metal thin film 2 shown in FIG. 7(a) to the opposite −z direction is shown in FIG. There are four patterns shown in 7(b) to 7(e), respectively.

The pattern of the position and direction of the reversing lead wire 3 with respect to the ferromagnetic metal thin film 2 for reversing the magnetization direction of the ferromagnetic metal thin film 2 in the -x direction to the opposite x direction shown in FIG. 7(f) is , there are four patterns shown in FIGS. 7(g) to 7(j), respectively. The pattern of the position and direction of the reversing lead wire 3 with respect to the ferromagnetic metal thin film 2 for reversing the direction of magnetization in the y direction of the ferromagnetic metal thin film 2 to the opposite −y direction shown in FIG. 7(k) is shown in FIG. There are four patterns shown in 7(l) to (o), respectively.

FIG. 8(a) is a perspective view showing the relationship between the ferromagnetic metal thin film 2 and the reversal lead wire 3 provided in the high-speed magnetization reversal device, and (b) to (i) are the ferromagnetic metal thin film 2 and the reversal lead wire 3. FIG. 4 is a perspective view showing various arrangements of auxiliary lead wires 4 with respect to lead wires 3; The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

FIG. 8 shows eight types of patterns of the positions and directions of the inversion lead wire 3 and the auxiliary lead wire 4 relative to the ferromagnetic metal thin film 2 for two-way injection. The position and direction of the auxiliary lead wire 4 with respect to the ferromagnetic metal thin film 2 and the reversal lead wire 3 for reversing the magnetization direction of the ferromagnetic metal thin film 2 in the y direction to the opposite −y direction shown in FIG. 8(a). There are eight patterns with terminal numbers 2 to 9 shown in FIGS. 8(b) to 8(i), respectively.

9(a) is a perspective view showing an aspect of the ferromagnetic metal thin film 2, and FIG. 9(b) is a perspective view showing another aspect of the ferromagnetic metal thin film 2. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

Regarding the ferromagnetic metal thin film 2 with dimensions of 10 nm x 20 nm x 6 nm shown in Fig. 9 (a), which has magnetization anisotropy due to shape and assumes permalloy (Py:FeNi alloy) as the ferromagnetic material, Fig. 8 (a) Table 1 shows simulation results of the magnetization reversal time for nine types of terminal structures with terminal numbers 1 to 9 shown in ) to (i).

As shown in Table 1, there is a slight difference in the magnetization reversal time depending on the difference in the terminal structure for terminal numbers 2 to 9, but compared to the magnetization reversal time for one terminal with terminal number 1. , the reversal of magnetization is significantly shortened for all of terminal numbers 2 to 9.

Regarding the ferromagnetic metal thin film 2 with dimensions of 10 nm x 10 nm x 6 nm shown in Fig. 9(b), assuming that the axis of magnetization is fixed due to endogenous magnetization anisotropy and the ferromagnetic material is (CoFe alloy), the figure Table 2 shows simulation results of the magnetization reversal time for nine types of terminal structures with terminal numbers 1 to 9 shown in 8(a) to 8(i). In order to align the reversal time at one terminal with terminal number 1 with the simulation results (about 10 ns) shown in Table 1, the value of the reversal spin current supplied to the reversal lead wire 3 was adjusted.

As shown in Table 2, irrespective of the type of magnetic anisotropy or the shape of the magnetic material, the magnetization reversal time of the ferromagnetic metal thin film 2 is This is significantly shorter than the magnetization reversal time for one terminal with terminal number 1.

[Embodiment 2]
10(a) is a perspective view of an experimental apparatus for the fast magnetization reversal device 1, FIG. 10(b) is a perspective view of the fast magnetization reversal device 1, and FIG. 10(c) is a circuit diagram of the fast magnetization reversal device 1. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

The experimental apparatus for the high-speed magnetization reversal device 1 includes a silicon substrate 17 . An inverted lead wire 3 and an auxiliary lead wire 4 made of platinum and having a film thickness of 10 nm are formed on a silicon substrate 17 so as to be perpendicular to each other. Then, a ferromagnetic metal thin film 2 made of a nickel-iron alloy and having a length of 2 μm, a width of 1 μm, and a film thickness of 10 nm or less is formed at a position where the reversal lead wire 3 and the auxiliary lead wire 4 intersect. Electrodes 11 containing gold/titanium are formed at both ends of the inverted lead wire 3. Electrodes 16 are formed at both ends of the auxiliary lead wire 4. A pair of measurement electrodes 15 are connected to the ferromagnetic metal thin film 2 for measuring the anisotropic magnetoresistive effect of the ferromagnetic metal thin film 2 in order to determine the magnetization direction of the ferromagnetic metal thin film 2 .

The experimental equipment for the high-speed magnetization reversal device 1 is provided with a current generating device 12 . The current generation device 12 includes an inversion current generator 13 for generating an inversion current and supplying it to the inversion lead wire 3, and an auxiliary current generator 14 for generating an auxiliary current and supplying it to the auxiliary lead wire 4. include.

One end of the reversing lead wire 3 is connected to one end of the coil 21. The other end of the reversing lead wire 3 is connected to one end of the coil 20. One end of the auxiliary lead wire 4 is connected to one end of the capacitor 19. The other end of the auxiliary lead wire 4 is connected to one end of the capacitor 22. A positive terminal of the power supply 23 is connected to the other end of the coil 21 and the other end of the capacitor 19. One end of switch 18 is connected to the other end of coil 20 and the other end of capacitor 22 . The other end of switch 18 is connected to the negative pole of power supply 23.

When the switch 18 is turned on, an auxiliary current flows through the auxiliary lead wire 4 until charges are stored in the capacitors 19 and 22. Further, in the reversing lead wire 3, the reversing current is suppressed by the coils 20 and 21 immediately after the switch 18 is turned on.

FIG. 11 is a schematic plan view of the magnetic memory device 10 according to the second embodiment. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

The magnetic memory device 10 includes a plurality of ferromagnetic metal thin films 2 arranged in a matrix, and an inverted spin current magnetized in the -y direction opposite to the y direction corresponding to the easy axis of magnetization of the ferromagnetic metal thin films 2. In order to inject into each ferromagnetic metal thin film 2, a plurality of inverted lead wires 3 are extended in the x direction and connected to each ferromagnetic metal thin film 2, and an auxiliary spin current magnetized in the x direction is injected into each ferromagnetic metal. In order to inject into the thin film 2, a plurality of auxiliary lead wires 4 are provided which extend along the y direction and connect to each ferromagnetic metal thin film 2.

FIG. 12 is a circuit diagram related to a write operation of the magnetic memory device 10 according to the second embodiment. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

To simplify the explanation, an example will be described in which the magnetic memory device 10 includes four ferromagnetic metal thin films m1-1, m1-2, m2-1, and m2-2 arranged in 2 rows and 2 columns. . The ferromagnetic metal thin films m1-1, m1-2, m2-1, and m2-2 correspond to the ferromagnetic metal thin film 2 shown in FIG.

The ferromagnetic metal thin films m1-1, m1-2, m2-1, and m2-2 are magnetized in the y direction corresponding to the easy axis of magnetization. In the magnetic memory device 10, in order to reverse the magnetization direction of the ferromagnetic metal thin films m1-1, m1-2, m2-1, m2-2, a reversal spin current magnetized in the -y direction is applied to the ferromagnetic metal thin film. An inverted lead wire 3a for injecting into the ferromagnetic metal thin films m2-1 and m2-2, and an inverted lead wire 3b for injecting an inverted spin current magnetized in the -y direction into the ferromagnetic metal thin films m2-1 and m2-2. , in order to assist in reversing the magnetization direction of the ferromagnetic metal thin films m1-1, m1-2, m2-1, m2-2, the auxiliary spin current magnetized in the x direction is transferred to the ferromagnetic metal thin films m2-1, m2. -1, and an auxiliary lead wire 4d for injecting an auxiliary spin current magnetized in the x direction into the ferromagnetic metal thin films m1-2 and m2-2.

The magnetic memory device 10 further includes main lines 24 and 25 for supplying reversal current to the reversal lead wires 3a and 3b, and auxiliary wires 26 and 27 for supplying auxiliary current to the auxiliary lead wires 4c and 4d.

A transistor a1 is arranged between the inverted lead wire 3a and the main line 24, and a transistor a2 is arranged between the inverted lead wire 3a and the main line 25. A transistor b1 is arranged between the inverted lead line 3b and the main line 24, and a transistor b2 is arranged between the inverted lead line 3b and the main line 25.

A transistor c2 is arranged between a part of the auxiliary lead wire 4c and another part of the auxiliary lead wire 4c. A transistor d2 is arranged between a part of the auxiliary lead wire 4d and another part of the auxiliary lead wire 4d.

A transistor c1 is arranged between a part of the auxiliary lead wire 4c and the auxiliary line 26, and a transistor c3 is arranged between the other part of the auxiliary lead wire 4c and the auxiliary line 27. A transistor d1 is arranged between a part of the auxiliary lead wire 4d and the auxiliary line 26, and a transistor d3 is arranged between the other part of the auxiliary lead wire 4d and the auxiliary line 27.

A terminal a is connected to the gate of the transistor a1 and the gate of the transistor a2. A terminal b is connected to the gate of the transistor b1 and the gate of the transistor b2. A terminal c is connected to the gate of the transistor c1, the gate of the transistor c2, and the gate of the transistor c3. A terminal d is connected to the gate of the transistor d1, the gate of the transistor d2, and the gate of the transistor d3.

The magnetic memory device 10 configured as described above executes a write operation as follows. FIG. 13 is a flowchart showing the write operation of the magnetic memory device 10.

At both ends of either the reversal lead wire 3a or 3b that is in contact with any one of the ferromagnetic metal thin films m1-1, m1-2, m2-1, m2-2 of the target whose magnetization is to be reversed. By turning on the two arranged transistors a1 and a2 or the transistors b1 and b2, an inverted current flows. By turning on transistors c1, c2, and c3, or transistors d1, d2, and d3 placed on either one of the auxiliary lead wires 4c or 4d in contact with the ferromagnetic metal thin film of the target, an auxiliary current is generated. Flow.

An example of a write operation when the ferromagnetic metal thin film m1-1 in FIG. 12 is used as a ferromagnetic metal as a write target will be shown below. First, the voltages of the main line 24 and the auxiliary line 26 are set to a high voltage (high), and the voltages of the main line 25 and the auxiliary line 27 are set to a low voltage (low) (step S1). Then, voltage is applied to terminal c to turn on transistors c1, c2, and c3. Then, an auxiliary current flows through the auxiliary lead wire 4c. Next, an auxiliary spin current directed in the x direction is injected into the ferromagnetic metal thin films m1-1 and m2-1 (step S2). Note that the above-mentioned high/low has the same meaning as high/low used in CMOS and digital circuits.

Thereafter, a voltage is applied to terminal a to turn on transistors a1 and a2. Then, a reversal current flows through the reversal lead wire 3a. Next, an inverted spin current directed in the -y direction is injected into the ferromagnetic metal thin films m1-1 and m1-2 (step S3). Immediately before or after the start of this operation, the voltage application to the terminal c is stopped to turn off the transistors c1, c2, and c3. Then, first, the magnetization direction of the ferromagnetic metal thin film m1-1 is reversed to the -y direction (step S4).

Then, when the voltage is continued to be applied to terminal a, the magnetization direction of the ferromagnetic metal thin film m1-2 is reversed in the -y direction, so before the magnetization direction of the ferromagnetic metal thin film m1-2 is reversed in the -y direction. The application of voltage to terminal a is stopped and transistors a1 and a2 are turned off (step S5).

The high/low direction of the main lines 24 and 25 is determined by the sign of the spinhole angle of the material of the inversion lead wire 3a.

The transistors c2 and c3 and the transistors d2 and d3 are necessary to prevent the reversal current flowing through the reversal lead wire 3a from going around to other ferromagnetic metal thin films. In other words, in this example, we want to flow current as follows: transistor a1 → ferromagnetic metal thin film m1-1 → ferromagnetic metal thin film m1-2 → transistor a2, but if transistor c2 is not transistor c2 but has a metal lead, the transistor A path for the current that flows as follows: a1 → ferromagnetic metal thin film m1-1 → ferromagnetic metal thin film m2-1 → ferromagnetic metal thin film m2-2 → ferromagnetic metal thin film m1-2 → transistor a2 also appears, so This is to prevent the appearance of undesirable current paths.

The voltage application time to the terminal c for causing the auxiliary current to flow through the auxiliary lead wire 4c is about 0.5 nsec. This voltage application time is approximately 2 GHz in terms of frequency, and can be controlled by the internal clock of the magnetic memory device 10.

To reverse the magnetization direction of the ferromagnetic metal thin film m1-1 from the -y direction to the y direction, the main line 24 is set to low and the main line 25 is set to high, reversing the high-low relationship between the main lines 24 and 25, and performing the steps above. Steps S2 to S5 are executed.

14(a) is a circuit diagram including parts related to the read operation of the magnetic memory device 10 according to the second embodiment, and FIG. 14(b) is a perspective view showing the TMR element 9 of the magnetic memory device 10. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

An insulating layer 5 is laminated on the ferromagnetic metal thin film m1-1, and a fixed layer 6 is laminated on the insulating layer 5. The ferromagnetic metal thin film m1-1, the insulating layer 5, and the fixed layer 6 constitute a TMR (Tunnel Magneto Resistance Effect) element 9. Similarly, an insulating layer 5 is laminated on the ferromagnetic metal thin films m1-2, 2-1, and 2-2, and a fixed layer 6 is laminated on each insulating layer 5. The ferromagnetic metal thin films m1-2, m2-1, m2-2, the insulating layer 5, and the fixed layer 6 each constitute a TMR element 9.

In order to read the magnetization direction of the ferromagnetic metal thin films m1-1 and m2-1, the readout lead wire 7a extends in the y direction and is joined to the corresponding fixed layer 6, and the ferromagnetic metal thin films m1-2 and m2-2. A reading lead wire 7b extending in the y direction and bonded to the corresponding fixed layer 6 is provided to read out the magnetization direction of the magnetization direction. A reading line 28 extending in the x direction is provided to read out the magnetization direction of the ferromagnetic metal thin films m1-1, m2-1, m1-1, and m2-1. A transistor e1 is arranged between the read lead line 7a and the read line 28, and a transistor f1 is arranged between the read lead line 7b and the read line 28. A terminal e is connected to the gate of the transistor e1, and a terminal f is connected to the gate of the transistor f1.

The magnetic memory device 10 supplies an inversion current to the inversion lead wires 3a and 3b, an auxiliary current to the auxiliary lead wires 4c and 4d, and a ferromagnetic metal thin film m1-1 from the readout lead wires 7a and 7b. A control circuit 29 is provided to control reading of the magnetization directions of m1-2, m2-1, and m2-2.

The main line 25 also serves as a reading line.

In the example shown in FIG. 14, the magnetization direction of the ferromagnetic metal thin film m1-1 is opposite to the magnetization direction of the corresponding pinned layer 6, so the magnetic resistance of the TMR element 9 is high, and the ferromagnetic metal thin film m1-1 has a high magnetic resistance. No current flows between the fixed layer 1 and the fixed layer 6. On the other hand, the magnetization directions of the other three ferromagnetic metal thin films m1-2, m2-1, and m2-2 are parallel to the magnetization direction of the pinned layer 6, so the magnetic resistance of the TMR element 9 is A current flows between the fixed layer 6 and the fixed layer 6.

The magnetic memory device 10 configured in this manner operates as follows.

The voltage on the reading line 28 is high. The voltage on the main line 24 is high. The voltage on the auxiliary line 26 is high, and the voltage on the auxiliary line 27 is low. Then, the voltage of the main line 25, which also serves as a reading line, is set to low.

When reading information stored in the ferromagnetic metal thin film m1-1, a voltage is applied to the terminal e and the terminal g to turn on the transistor e1 and the transistor a2, respectively. Then, since the TMR element 9 corresponding to the ferromagnetic metal thin film m1-1 has a high resistance, no current flows. Although the TMR element 9 corresponding to the ferromagnetic metal thin film m2-1 has a low resistance, since the transistors b2, c2, c3, d2, and d3 are off, the TMR element 9 of the ferromagnetic metal thin film m2-1 No current flows through it. The potential of the main line 25, which also serves as a reading line, becomes lower than the potential of the reading line 28 (becomes low). As a result, the information stored in the ferromagnetic metal thin film m1-1 can be read out as "0".

When reading information stored in the ferromagnetic metal thin film m2-2, a voltage is applied to the terminal f and the terminal h to turn on the transistor f1 and the transistor b2, respectively. Then, although the TMR element 9 corresponding to the ferromagnetic metal thin film m1-2 has a low resistance, since the transistors a2, c2, c3, d2, and d3 are off, the TMR element 9 of the ferromagnetic metal thin film m1-2 No current flows through it. Since the TMR element 9 corresponding to the ferromagnetic metal thin film m2-2 has a low resistance, current flows from the transistor f1 through the ferromagnetic metal thin film m2-2 and through the transistor b2 to the main line 25 which also serves as a reading line. flows. As a result, the potential of the main line 25, which also serves as a reading line, becomes high, the same as the potential of the reading line 28. As a result, it is determined that the information stored in the ferromagnetic metal thin film m2-2 is "1".

A high voltage state corresponds to "1", and a low voltage state corresponds to "0". The operation of the main line 25, which is also used as a read line, is similar to the operation of the bit line during DRAM reading. As shown in FIG. 14, instead of using the transistors a2 and b2 and the main line 25 for both the write operation and the read operation, other transistors and other read lines may be separately provided in parallel. In FIG. 14, illustration of the transistors c2 and d2 described above in FIG. 12 is omitted for simplicity.

FIG. 15 is a circuit diagram related to a modification of the write operation described above in FIG. 12. The components described above are given the same reference numerals and detailed descriptions thereof will not be repeated.

The write circuit of the magnetic memory device 10 shown in FIG. 12 can be replaced by the write circuit shown in FIG. 15. The points different from the write circuit in FIG. 12 are that transistors a1, b1, c1, and d1 are connected to a common main line 24A, transistors a2, b2, c3, and d3 are connected to a common main line 25A, and transistors A point where individual terminals g1 and g2 are connected to a1 and a2, respectively, a point where individual terminals h1 and h2 are connected to transistors b1 and b2, respectively, and an individual terminal e1, e2, and e3 to transistors c1, c2, and c3. are connected to the transistors d1, d2, and d3, respectively, and individual terminals f1, f2, and f3 are connected to the transistors d1, d2, and d3, respectively.

The write circuit of the magnetic memory device 10A shown in FIG. 15 has fewer transistors in the auxiliary current path than the write circuit of FIG. 12, and has lower power consumption than the write circuit of FIG. The inversion current and auxiliary current in the write circuit of FIG. 15 are caused to flow as follows.

At both ends of either the reversal lead wire 3a or 3b that is in contact with any one of the ferromagnetic metal thin films m1-1, m1-2, m2-1, m2-2 of the target whose magnetization is to be reversed. By turning on the two arranged transistors a1 and a2 or the transistors b1 and b2, an inverted current flows as in the write circuit of FIG. 12. The transistor on the left end of the reversing lead line one level above the paper and the reversing lead one level below from the target ferromagnetic metal thin film m1-1, m1-2, m2-1, m2-2. An auxiliary current is caused to flow by turning on a total of four transistors: the transistor on the right end of the line, and the two transistors on the top and bottom of the paper located close to the target ferromagnetic thin film installed on the auxiliary lead wire in contact with the target ferromagnetic thin film. . However, if the target is a ferromagnetic thin film in the top row or a ferromagnetic thin film in the bottom row, the number of transistors to be turned on is reduced by one as shown in FIG.

For example, when the target whose magnetization is to be reversed is the ferromagnetic metal thin film m2-1, a reversal current is caused to flow by turning on transistors b1 and b2 arranged at both ends of the reversal lead wire 3b. Then, the transistor a1 at the left end of the reversing lead wire 3a one above the reversing lead wire 3b, the transistor b2 at the right end of the reversing lead wire 3b one below, and the upper and lower transistors located near the target ferromagnetic thin film m2-1. Auxiliary current is caused to flow by turning on a total of four transistors a1, b2, c2, and c3 (transistors c2 and c3).

In the case of the write circuit shown in FIG. 15, the gates of the transistors a1, a2, b1, b2, c1, c2, c3, d1, d2, and d3 must all be controlled independently. Further, the auxiliary lines 26 and 27 shown in FIG. 12 are no longer necessary in the write circuit of FIG.

(summary)
A high-speed magnetization reversal method according to aspect 1 of the present invention is a high-speed magnetization reversal method in which the magnetization of a ferromagnetic metal layer in a metal layer structure in which one or two non-magnetic metal layers and a ferromagnetic metal layer are laminated is reversed by spin-orbit torque. In the magnetization reversal method, the ferromagnetic metal layer is given uniaxial magnetic anisotropy in advance so that the easy axis of magnetization is in a specific direction, and a spin injection magnetization reversal step of injecting a reversal spin current from the non-magnetic metal layer to the ferromagnetic metal layer to induce magnetization reversal; and a spin injection magnetization reversal step from the same or different non-magnetic metal layer to the ferromagnetic metal layer. an auxiliary spin current injection step of injecting an auxiliary spin current for a short period of time, the two types of spin currents, the reversed spin current and the auxiliary spin current, in which the directions of magnetization of the spin currents are different from each other, are transferred to the ferromagnetic Inject into the metal layer at different times.

In the fast magnetization reversal method according to aspect 2 of the present invention, one or two nonmagnetic metal layers are one nonmagnetic metal layer, and the auxiliary spin current injection step injects auxiliary spin current from the same nonmagnetic metal layer. Injection is preferred.

In the fast magnetization reversal method according to aspect 3 of the present invention, the one or two nonmagnetic metal layers are two nonmagnetic metal layers, and the auxiliary spin current injection step injects auxiliary spin current from another nonmagnetic metal layer. Injection is preferred.

In the fast magnetization reversal method according to aspect 4 of the present invention, the reversal spin current of the spin injection magnetization reversal step is carried out at an appropriate timing after performing the auxiliary spin current injection step in addition to the spin injection magnetization reversal step. Preferably, the auxiliary spin current is injected into the ferromagnetic metal layer throughout the entire time, and the auxiliary spin current is injected while the reversal spin current is being injected into the ferromagnetic metal layer.

In the fast magnetization reversal method according to aspect 5 of the present invention, it is preferable that the auxiliary spin current starts to be injected into the ferromagnetic metal layer immediately after or simultaneously with the start of the spin injection magnetization reversal step.

In the fast magnetization reversal method according to the sixth aspect of the present invention, it is preferable that the auxiliary spin current starts to be injected into the ferromagnetic metal layer immediately before the start of the spin injection magnetization reversal step.

In the fast magnetization reversal method according to aspect 7 of the present invention, the nonmagnetic metal layer in the spin injection magnetization reversal step is reversed so that the magnetization direction is parallel to the easy axis direction of the ferromagnetic metal layer. Preferably, a spin current is injected.

In the fast magnetization reversal method according to aspect 8 of the present invention, it is preferable that the nonmagnetic metal layer includes a main lead layer extending in a direction perpendicular to the axis of easy magnetization.

In the fast magnetization reversal method according to aspect 9 of the present invention, it is preferable that the main lead layer is made of the same material as the nonmagnetic metal layer, metal, or other material with low electrical resistance.

In the fast magnetization reversal method according to aspect 9 of the present invention, it is preferable that the main lead layer is made of the same material as the nonmagnetic metal layer, metal, or other material with low electrical resistance.

In the fast magnetization reversal method according to aspect 10 of the present invention, in the auxiliary spin current injection step, from either the nonmagnetic metal layer or another nonmagnetic metal layer to the ferromagnetic metal layer, in the direction of the easy axis of magnetization of the ferromagnetic metal layer. Preferably, an auxiliary spin current having a magnetization direction perpendicular to is injected.

In the fast magnetization reversal method according to aspect 11 of the present invention, either the nonmagnetic metal layer or another nonmagnetic metal layer has an auxiliary lead extending in a direction parallel to the easy axis of magnetization of the ferromagnetic metal layer. Preferably, it includes a layer.

In the fast magnetization reversal method according to aspect 12 of the present invention, the direction of magnetization in the direction perpendicular to the easy axis direction of the ferromagnetic metal layer is changed from another non-magnetic metal layer to the ferromagnetic metal layer in the auxiliary spin current injection step. It is preferable that an auxiliary spin current with a

In the fast magnetization reversal method according to aspect 13 of the present invention, the another non-magnetic metal layer is arranged in a direction perpendicular to the easy axis of magnetization of the ferromagnetic metal layer, and with respect to the injection direction of the reversal spin current. It is preferable to include an auxiliary lead layer extending in a direction orthogonal to the lead layer.

In the fast magnetization reversal method according to aspect 14 of the present invention, the nonmagnetic metal layer and another nonmagnetic metal layer are preferably joined to the ferromagnetic metal layer by coming into contact with the main surface or side surface of the ferromagnetic metal layer. .

A fast magnetization reversal device according to aspect 15 of the present invention includes one or two nonmagnetic metal layers and a ferromagnetic metal layer laminated with the nonmagnetic metal layer, the nonmagnetic metal layer and the ferromagnetic metal layer. A high-speed magnetization reversal device for reversing the magnetization of the ferromagnetic metal layer in a metal layer structure using spin-orbit torque, the ferromagnetic metal layer having uniaxial magnetic anisotropy such that a specific direction is an axis of easy magnetization. a spin injection magnetization reversal step of injecting a reversal spin current from the non-magnetic metal layer to the ferromagnetic metal layer in order to induce magnetization reversal on the easy axis of magnetization of the ferromagnetic metal layer; This and an auxiliary spin current injection step of injecting an auxiliary spin current from the same or different non-magnetic metal layer to the ferromagnetic metal layer for a short time, and the reversal in which the magnetization directions of the spin currents are different from each other. Two types of spin currents, a spin current and the auxiliary spin current, are injected into the ferromagnetic metal layer at different times.

In the fast magnetization reversal device according to aspect 16 of the present invention, the ferromagnetic metal layer includes a NiFe-based binary alloy, a CoFeB alloy, or a ferromagnetic material having a finite spin polarization near room temperature, and the ferromagnetic metal layer contains a nonmagnetic metal layer. Preferably, at least one of the layer and the other nonmagnetic metal layer contains at least one of Pt, Ru, and other metals with a large absolute value of the spin Hall angle.

The fast magnetization reversal device according to aspect 17 of the present invention includes an insulating layer laminated on the ferromagnetic metal layer, a pinned layer laminated on the insulating layer and magnetized in the direction of the easy axis of magnetization, and a ferromagnetic metal layer. a readout lead bonded to the pinned layer for reading out the magnetization direction of the metal layer, a current to the non-magnetic metal layer for reversal spin current, and another non-magnetic metal for current for the auxiliary spin current. Preferably, the device further includes a control circuit for controlling supply to the layer and readout of the magnetization direction of the ferromagnetic metal layer from the readout lead.

A magnetic memory device according to aspect 18 of the present invention includes a plurality of tunnel magnetoresistive elements arranged in a matrix, and the tunnel magnetoresistive element is arranged between a fixed layer, a free layer, and a fixed layer and a free layer. an insulating layer formed, and a transverse direction intersecting the first direction for injecting into the free layer a reversed spin current magnetized in a reverse direction opposite to the first direction corresponding to the easy axis of magnetization of the free layer. a plurality of inverted lead wires extending along the first direction and joining each free layer; and a plurality of readout lead wires extending along the first direction or the cross direction and joining each fixed layer in order to read the magnetization direction of each free layer. .

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. are also included within the technical scope of the present invention.

1 High-speed magnetization reversal device 2 Ferromagnetic metal thin film (ferromagnetic metal layer)
3 Inversion lead wire (non-magnetic metal layer, main lead layer)
4 Auxiliary lead wire (non-magnetic metal layer, another non-magnetic metal layer, auxiliary lead layer)
5 Insulating layer 6 Fixed layer 7a Read lead wire 7b Read lead wire 9 TMR element (tunnel magnetoresistive element)
10 Magnetic memory device 29 Control circuit

Claims (13)

a ferromagnetic metal layer having an easy axis of magnetization in a first direction ; a first non-magnetic metal layer stretched in a direction crossing the first direction and joined to the ferromagnetic metal layer; a second non-magnetic metal layer stretched in a parallel direction or a direction perpendicular to the first direction and bonded to the ferromagnetic metal layer; A high-speed magnetization reversal method in which the magnetization is reversed by torque,
reversal of magnetization from the first non-magnetic metal layer to the ferromagnetic metal layer in a direction parallel to the first direction to induce magnetization reversal on the easy axis of magnetization of the ferromagnetic metal layer; a spin injection magnetization reversal step for injecting a spin current;
and an auxiliary spin current injection step of injecting an auxiliary spin current magnetized in a cross direction intersecting the first direction from the second nonmagnetic metal layer to the ferromagnetic metal layer. Method. 2. The high-speed magnetization reversal method according to claim 1, wherein a part of the first non-magnetic metal layer and a part of the second non-magnetic metal layer are common . The reversal spin current of the spin injection magnetization reversal step is injected into the ferromagnetic metal layer throughout the entire time during magnetization reversal, and the auxiliary spin current is injected into the ferromagnetic metal layer while the reversal spin current is injected into the ferromagnetic metal layer. The high-speed magnetization reversal method according to claim 1, characterized in that the method comprises injecting. 4. The fast magnetization reversal method according to claim 3, wherein the auxiliary spin current starts to be injected into the ferromagnetic metal layer simultaneously with the spin injection magnetization reversal step. 2. The fast magnetization reversal method according to claim 1, wherein the auxiliary spin current starts to be injected into the ferromagnetic metal layer immediately before the start of the spin injection magnetization reversal step. 2. The high-speed magnetization reversal method according to claim 1, wherein the first nonmagnetic metal layer includes a main lead layer extending in a direction intersecting the first direction of the ferromagnetic metal layer. 2. The high-speed magnetization reversal method according to claim 1, wherein the second nonmagnetic metal layer includes an auxiliary lead layer extending in a direction parallel to the first direction of the ferromagnetic metal layer. 1 . The first nonmagnetic metal layer and the second nonmagnetic metal layer are bonded to the ferromagnetic metal layer by coming into contact with a main surface or a side surface of the ferromagnetic metal layer. The high-speed magnetization reversal method described in . a ferromagnetic metal layer whose axis of easy magnetization is a first direction;
a first non-magnetic metal layer stretched in a direction crossing the first direction and joined to the ferromagnetic metal layer;
a second non-magnetic metal layer stretched in a direction parallel to the first direction or in a direction perpendicular to the first direction and joined to the ferromagnetic metal layer;
A reversed spin current magnetized in a direction parallel to the first direction is injected from the first nonmagnetic metal layer into the ferromagnetic metal layer,
An auxiliary spin current magnetized in a cross direction intersecting the first direction is injected from the second nonmagnetic metal layer into the ferromagnetic metal layer to assist magnetization reversal,
A high-speed magnetization reversal device in which the magnetization of the ferromagnetic metal layer is reversed by spin-orbit torque by the reverse spin current and the auxiliary spin current . The ferromagnetic metal layer includes a NiFe-based binary alloy, a CoFeB alloy, or a ferromagnetic material having a finite spin polarization near room temperature,
10. At least one of the first nonmagnetic metal layer and the second nonmagnetic metal layer contains at least one of Pt, Ru, and other metals having a large absolute value of the spin Hall angle. The described fast magnetization reversal device. The fast magnetization reversal device according to claim 9, wherein a part of the first nonmagnetic metal layer and a part of the second nonmagnetic metal layer are common.. A fast magnetization reversal device according to claim 9;
an insulating layer laminated on the ferromagnetic metal layer of the fast magnetization reversal device;
a fixed layer stacked on the insulating layer and magnetized in the direction of the easy axis of magnetization;
a readout lead wire joined to the fixed layer for reading out the magnetization direction of the ferromagnetic metal layer;
supplying a current for the reversal spin current to the first non-magnetic metal layer; supplying a current for the auxiliary spin current to the second non-magnetic metal layer; a control circuit that controls readout of the magnetization direction from the readout lead wire;
A magnetic memory device comprising : Equipped with multiple tunnel magnetoresistive elements arranged in a matrix,
The tunnel magnetoresistive element includes a fixed layer, a free layer, and an insulating layer formed between the fixed layer and the free layer,
In order to inject into the free layer an inverted spin current magnetized in an inverted direction opposite to the first direction corresponding to the easy axis of magnetization of the free layer, extending along a transverse direction intersecting the first direction. a plurality of inverted lead wires connected to each free layer;
a plurality of auxiliary lead wires extending along the first direction and joining each free layer in order to inject the auxiliary spin current magnetized in the cross directions into the free layer;
A magnetic memory device comprising: a plurality of read lead wires extending along the first direction or the intersecting direction and connected to each fixed layer in order to read the magnetization direction of each free layer.

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