WO2023178595A1

WO2023178595A1 - Magnetic storage unit and magnetic storage device

Info

Publication number: WO2023178595A1
Application number: PCT/CN2022/082725
Authority: WO
Inventors: 石以诺; 张文彪; 迟克群; 李州; 孟皓
Original assignee: 中电海康集团有限公司
Priority date: 2022-03-21
Filing date: 2022-03-24
Publication date: 2023-09-28
Also published as: CN116828965A

Abstract

Provided in the present invention are a magnetic storage unit and a magnetic storage device. The magnetic storage unit comprises: a first free layer, a first coupling layer, a second free layer, a barrier layer and a reference layer, which are sequentially arranged in a stacked manner. A logic storage state of the magnetic storage unit is determined according to resistance states at two ends of the magnetic storage unit; and by means of applying a voltage pulse, the pulse width of which exceeds a pulse width threshold value, to the two ends of the magnetic storage unit, the resistance states at the two ends of the magnetic storage unit are subjected to unipolarity switching. In the present application, a pulse voltage is used to drive the magnetic storage unit to turn over; the present application has the advantages of low power consumption and high storage density; and there is no need to accurately control the pulse width of the voltage pulse, such that the difficulty of control over the pulse width is reduced.

Description

A kind of magnetic storage unit and magnetic storage device

Technical field

The present invention relates to the field of storage technology, and in particular to a magnetic storage unit and a magnetic storage device.

Background technique

With the rise of connected smart devices, there is an increasing demand for high-performance data storage and memory technology. The current memory technology is dynamic random access memory (DRAM). The storage mechanism of DRAM is to store data in the form of electric charge in a capacitor. Data stored in this way can be damaged due to leakage or discharge of the capacitor. Therefore, DRAM needs to be charged periodically to protect data, which greatly increases the power consumption of the memory. In addition, the shrinkage of DRAM cells is also constrained by capacitors. It is necessary to ensure that the amount of charge stored in the capacitor remains unchanged after shrinkage. This makes it increasingly difficult to increase the storage density of DRAM through shrinkage.

In recent years, new non-volatile memory technologies have developed rapidly. Non-volatile memory refers to memory that stores data that does not disappear when the external power supply disappears. Non-volatile memory does not need to refresh data repeatedly, and static power consumption is very low. At present, common non-volatile memory cells are mainly two-terminal structure variable resistance devices. The resistance characteristics of the memory cell can be changed between a high resistance state and a low resistance state by applying pulse current. However, on the one hand, this current-driven working method will bring high dynamic power consumption. On the other hand, it requires a large area of external circuit for power supply, and the storage density is low.

Contents of the invention

The invention provides a magnetic storage unit and a magnetic storage device, which have the advantages of low power consumption and high storage density. They do not need to accurately control the pulse width of voltage pulses and reduce the difficulty of pulse width control.

In a first aspect, the present invention provides a magnetic memory unit, which includes a first free layer, a first coupling layer, a second free layer, a barrier layer and a reference layer that are stacked in sequence. Among them, the logical storage state of the magnetic storage unit is determined based on the resistance state at both ends of the magnetic storage unit; and by applying a voltage pulse width to both ends of the magnetic storage unit that exceeds the pulse width threshold, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching.

In the above scheme, by adding a first coupling layer and a first free layer to the original magnetic tunnel junction composed of a free layer, a barrier layer and a reference layer, a voltage is applied to both ends of the magnetic memory unit. When the pulse width exceeds the pulse width threshold, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching, allowing the magnetic storage unit to complete switching between two logical storage devices. Compared with the existing technology that uses pulse current to drive the magnetic storage unit to flip, this application uses pulse voltage to drive the magnetic storage unit to flip. There is almost no need for current pulse driving during operation. As long as the voltage changes, voltage is applied to both ends of the magnetic storage unit. pulse until the voltage pulse width is greater than the pulse width threshold, the resistance state switching of the magnetic memory unit can be quickly completed. That is to say, this application realizes the control of the logical storage state of the magnetic storage unit based entirely on voltage pulses, without the need for current pulse driving, and correspondingly does not require a large-area external circuit for power supply, reducing the area of the power supply circuit, and enabling more magnetic storage units to be installed, thereby having With the advantages of low power consumption and high storage density, it can be used as the basic unit of low-power, high-density non-volatile memory in the future. At the same time, after a voltage pulse is applied for a long enough time, the resistance state of the magnetic memory unit can be switched to unipolarity, eliminating the need to precisely control the pulse width of the voltage pulse and reducing the difficulty of pulse width control.

In a specific embodiment, the reference layer has perpendicular magnetic anisotropy with a constant perpendicular magnetization direction, the first free layer and the second free layer both have perpendicular magnetic anisotropy with a perpendicular magnetization direction that can be flipped, and the second free layer There is also a voltage-controlled magnetic anisotropy effect. Based on the voltage-controlled magnetic anisotropy effect, by applying a voltage pulse width exceeding the pulse width threshold to both ends of the magnetic memory cell, a unipolar magnetization flip occurs in the perpendicular magnetization directions of the first free layer and the second free layer, causing the reference layer to The magnetization direction between the second free layer and the second free layer is switched between a parallel state and an anti-parallel state, which facilitates unipolar switching of the resistance state of the magnetic memory cell.

In a specific embodiment, when a voltage pulse is applied to both ends of the magnetic memory cell, the second free layer switches from perpendicular magnetic anisotropy to in-plane magnetic anisotropy based on the voltage-controlled magnetic anisotropy effect, and The vertical magnetization direction of the first free layer is driven to oscillate through the first coupling layer. After the voltage pulse width exceeds the pulse width threshold, the perpendicular magnetization direction of the first free layer stabilizes in the opposite direction of the perpendicular magnetization direction before oscillation, and the magnetization direction of the second free layer stabilizes in the in-plane magnetization direction. After the voltage pulse is removed, the first free layer passes through the first coupling layer, and the magnetization direction of the second free layer is flipped from the in-plane magnetization direction to the perpendicular magnetization direction that is the same as the magnetization direction of the first free layer. It is convenient to drive the perpendicular magnetization direction of the first free layer and the second free layer to flip from the initial direction and unipolarity to the opposite direction.

In a specific implementation, the coupling strength of the first coupling layer is 0.02˜0.1erg/cm ² . The free layer damping coefficient composed of the first free layer, the first coupling layer and the second free layer is 0.005~0.05, which facilitates the process of applying voltage pulses. The first free layer is finally stabilized in the direction opposite to the initial perpendicular magnetization direction. The two free layers are stabilized in the in-plane magnetization direction.

In a specific implementation, the pulse width threshold is 1 to 10 ns, which reduces the time for applying the voltage pulse.

In a specific embodiment, the barrier layer is used to provide a voltage-controlled magnetic anisotropy effect to the second free layer, and is also used to provide a tunneling magnetoresistance effect to the second free layer and the reference layer, so as to facilitate the second free layer. The free layer has a voltage-controlled magnetic anisotropy effect, which also facilitates the realization of the tunneling magnetoresistance effect between the second free layer, the barrier layer and the reference layer.

In a specific embodiment, the material of the barrier layer is magnesium oxide to obtain a more significant tunneling magnetoresistance effect and voltage-controlled magnetic anisotropy effect.

In a specific embodiment, a magnesium oxide layer is laminated on the first free layer, and the magnesium oxide layer and the first coupling layer are arranged on opposite sides of the first free layer. The magnesium oxide layer is used to increase the perpendicular magnetic anisotropy of the first free layer, and the thickness of the magnesium oxide layer is smaller than the thickness of the barrier layer. While enhancing the perpendicular magnetic anisotropy of the first free layer, it is necessary to reduce the thickness of the magnesium oxide layer as much as possible to reduce the partial voltage when an external voltage pulse is applied, thereby reducing the impact on the magnetoresistance change rate. Moreover, it is also necessary to make the thickness of the barrier layer larger to increase the resistance of the barrier layer, so that when a voltage pulse is applied externally, there will be more voltage division.

In a specific embodiment, a heavy metal layer is laminated on the first free layer, and the heavy metal layer and the first coupling layer are arranged on opposite sides of the first free layer. The heavy metal layer is used to enhance the perpendicular magnetic anisotropy of the first free layer. While enhancing the perpendicular magnetic anisotropy of the first free layer, the low resistance characteristics of the heavy metal layer are utilized to reduce the impact on the magnetoresistance change rate. It also utilizes the magnetic anisotropy effect of the heavy metal layer that does not have voltage control, so that the heavy metal layer does not affect the unipolar switching of the magnetic memory unit and does not affect the operation of the device. And by arranging a heavy metal layer, the free layer damping coefficient between the first free layer, the first coupling layer and the second free layer can also be improved, which facilitates the control of the overall flip time and flip probability of the magnetic memory array.

In a specific embodiment, the magnetic memory unit further includes: a second coupling layer and a pinning layer sequentially stacked on the reference layer. The pinned layer passes through the second coupling layer to pin the reference layer to have perpendicular magnetic anisotropy with a constant perpendicular magnetization direction, so as to facilitate pinning the perpendicular magnetization direction of the reference layer.

In a specific embodiment, the first coupling layer is ferromagnetic coupling, the second coupling layer is antiferromagnetic coupling, and the coupling strength of the second coupling layer is greater than the coupling strength of the first coupling layer, so that the perpendicular magnetization direction of the reference layer It is not affected by the magnetization directions of the two free layers, but maintains a constant perpendicular magnetization direction.

In a specific embodiment, the materials of the first coupling layer and the second coupling layer are Ru, Ir, Ta, Mo or W, which facilitates the arrangement of the two coupling layers.

In a specific embodiment, the material of the pinning layer is FeNi, FePd, CoNi, FePt or CoPt, which facilitates the placement of the pinning layer.

In a specific embodiment, the material of the first free layer, the second free layer and the reference layer is any one of Co, Fe, Ni or an alloy containing several materials, which facilitates the arrangement of the free layer and the reference layer.

In a second aspect, the present invention also provides a magnetic memory device, which includes: a magnetic memory array composed of a plurality of any of the above magnetic memory cells, and a pulse voltage generating circuit. Wherein, the pulse voltage generating circuit is used to apply a voltage pulse with a pulse width exceeding a pulse width threshold to both ends of the magnetic memory unit, so that the resistance state at both ends of the magnetic memory unit undergoes unipolar switching. By adding a first coupling layer and a first free layer to the original magnetic tunnel junction composed of a free layer, a barrier layer and a reference layer, a voltage pulse width exceeding the pulse width threshold is applied to both ends of the magnetic memory cell. , causing the resistance state at both ends of the magnetic storage unit to undergo unipolar switching, allowing the magnetic storage unit to complete switching between two logical storage devices. Compared with the existing technology that uses pulse current to drive the magnetic storage unit to flip, this application uses pulse voltage to drive the magnetic storage unit to flip. There is almost no need for current pulse driving during operation. As long as the voltage changes, voltage is applied to both ends of the magnetic storage unit. pulse until the voltage pulse width is greater than the pulse width threshold, the resistance state switching of the magnetic memory unit can be quickly completed. That is to say, this application realizes the control of the logical storage state of the magnetic storage unit based entirely on voltage pulses, without the need for current pulse driving, and correspondingly does not require a large-area external circuit for power supply, reducing the area of the power supply circuit, and enabling more magnetic storage units to be installed, thereby having With the advantages of low power consumption and high storage density, it can be used as the basic unit of low-power, high-density non-volatile memory in the future. At the same time, after a voltage pulse is applied for a long enough time, the resistance state of the magnetic memory unit can be switched to unipolarity, eliminating the need to precisely control the pulse width of the voltage pulse and reducing the difficulty of pulse width control.

Description of the drawings

Figure 1 is a structural cross-sectional view of a magnetic memory unit provided by an embodiment of the present invention;

Figure 2 is a schematic diagram illustrating changes in the magnetization state and barrier structure after applying a voltage pulse according to an embodiment of the present invention;

Figure 3 is a structural cross-sectional view of another magnetic memory unit provided by an embodiment of the present invention;

Figure 4 is a structural cross-sectional view of another magnetic memory unit provided by an embodiment of the present invention;

Figure 5 is a structural cross-sectional view of another magnetic memory unit provided by an embodiment of the present invention;

FIG. 6 is a structural cross-sectional view of another magnetic memory unit provided by an embodiment of the present invention.

Reference signs:

11-First free layer 12-Second free layer 21-First coupling layer

22-Second coupling layer 30-Barrier layer 40-Reference layer 50-Pinning layer

61-Magnesia layer 62-Heavy metal layer 70-Top electrode 80-Bottom electrode

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In order to facilitate understanding of the magnetic storage unit provided by the embodiment of the present invention, the application scenarios of the magnetic storage unit provided by the embodiment of the present invention are first described below. The magnetic storage unit is used as a storage bit and is used in a magnetic storage device. The magnetic memory unit will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2 , the magnetic memory unit provided by the embodiment of the present invention includes: a first free layer 11 , a first coupling layer 20 , a second free layer 12 , a barrier layer 30 and a reference layer 40 that are stacked in sequence. Wherein, the logical storage state of the magnetic storage unit is determined based on the resistance state at both ends of the magnetic storage unit; and by applying a voltage pulse width exceeding the pulse width threshold to both ends of the magnetic storage unit, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching.

In the above scheme, by adding the first coupling layer 20 and the first free layer 11 to the original magnetic tunnel junction composed of the free layer, the barrier layer 30 and the reference layer 40, the magnetic memory cell is When the voltage pulse width applied at both ends exceeds the pulse width threshold, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching, allowing the magnetic storage unit to complete switching between two logical storage devices. Compared with the existing technology that uses pulse current to drive the magnetic storage unit to flip, this application uses pulse voltage to drive the magnetic storage unit to flip. There is almost no need for current pulse driving during operation. As long as the voltage changes, voltage is applied to both ends of the magnetic storage unit. pulse until the voltage pulse width is greater than the pulse width threshold, the resistance state switching of the magnetic memory unit can be quickly completed. That is to say, this application realizes the control of the logical storage state of the magnetic storage unit based entirely on voltage pulses, without the need for current pulse driving, and correspondingly does not require a large-area external circuit for power supply, reducing the area of the power supply circuit, and enabling more magnetic storage units to be installed, thereby having With the advantages of low power consumption and high storage density, it can be used as the basic unit of low-power, high-density non-volatile memory in the future. At the same time, after a voltage pulse is applied for a long enough time, the resistance state of the magnetic memory unit can be switched to unipolarity, eliminating the need to precisely control the pulse width of the voltage pulse and reducing the difficulty of pulse width control. Each of the above structures will be introduced in detail below with reference to the accompanying drawings.

When setting, referring to FIG. 1 , the first free layer 11 , the first coupling layer 20 , the second free layer 12 , the barrier layer 30 and the reference layer 40 are stacked in sequence from top to bottom. It should be understood that the stacking direction of the first free layer 11 , the first coupling layer 20 , the second free layer 12 , the barrier layer 30 and the reference layer 40 is not limited to the top-to-bottom stacking as shown in FIG. 1 In addition, other stacking methods can also be used. For example, the first free layer 11, the first coupling layer 20, the second free layer 12, the barrier layer 30 and the reference layer 40 can also be sequentially stacked from bottom to top. Do the layering. The second free layer 12, the barrier layer 30 and the reference layer 40 form a magnetic tunnel junction structure, that is, the magnetization direction between the second free layer 12 and the reference layer 40 can be between a parallel state and an anti-parallel state. flip, thereby changing the resistance state across the magnetic memory cell. The barrier layer 30 can provide the tunneling magnetoresistance effect to the second free layer 12 and the reference layer 40 to facilitate the realization of the tunneling magnetoresistance effect between the second free layer 12 , the barrier layer 30 and the reference layer 40 . Specifically, when the magnetization directions between the second free layer 12 and the reference layer 40 are parallel, that is, the magnetization directions of the two are the same, the resistance state at both ends of the magnetic memory cell is in a low resistance state. When the magnetization directions between the second free layer 12 and the reference layer 40 are antiparallel, that is, the magnetization directions of the two are exactly opposite, the resistance state at both ends of the magnetic memory cell is in a high resistance state. The magnetic storage unit also represents the two logical storage states of the magnetic storage unit through the high resistance state and the low resistance state respectively. That is, the logical storage state of the storage unit is determined according to the resistance state at both ends of the magnetic storage unit, thereby realizing the reading of data. Write.

When the reference layer 40 is provided, the reference layer 40 has perpendicular magnetic anisotropy with a constant perpendicular magnetization direction, that is, the perpendicular magnetization direction within the reference layer 40 can maintain a constant upward direction as shown in FIG. 1 . Specifically, as shown in FIG. 1 , the second coupling layer 22 and the pinning layer 50 provided on the reference layer 40 can be sequentially stacked on the side of the reference layer 40 away from the barrier layer 30 , and the pinning layer 50 passes through the third layer. The second coupling layer 22 pins the reference layer 40 to have perpendicular magnetic anisotropy with a constant perpendicular magnetization direction, which facilitates pinning the perpendicular magnetization direction of the reference layer 40 . When determining the material of the reference layer 40 , refer to FIGS. 4 and 6 . The material of the reference layer 40 can be any one of Co, Fe, and Ni or an alloy containing several materials, which facilitates the setting of the reference layer 40 . When determining the material of the pinning layer 50 , refer to FIG. 4 and FIG. 6 . The material of the pinning layer 50 can be FeNi, FePd, CoNi, FePt or CoPt, which facilitates the arrangement of the pinning layer 50 . When determining the material of the second coupling layer 22, refer to FIG. 4 and FIG. 6. The material of the second coupling layer 22 may be Ru, Ir, Ta, Mo or W, which facilitates the placement of the second coupling layer 22. It should be understood that the manner of pinning the perpendicular magnetization direction of the reference layer 40 is not limited to the manner shown above, and other pinning manners may also be adopted.

When the above-mentioned first free layer 11, first coupling layer 20 and second free layer 12 are provided, as shown in FIG. 1, the second free layer 12 is separated from the reference layer 40 by the barrier layer 30, and the first free layer 11 is separated from the second free layer 12 by a first coupling layer 20 . Both the first free layer 11 and the second free layer 12 have perpendicular magnetic anisotropy in which the perpendicular magnetization direction can be flipped, that is, the perpendicular magnetization directions in the first free layer 11 and the second free layer 12 can be as shown in Figure 1 to flip between up and down. And the second free layer 12 also has a voltage-controlled magnetic anisotropy effect, which can be provided specifically by the barrier layer 30 . That is, in addition to providing the tunneling magnetoresistance effect to the second free layer 12 and the reference layer 40 as shown above, the barrier layer 30 can also provide a voltage-controlled magnetic anisotropy effect to the second free layer 12 to facilitate the use of the second free layer 12 and the reference layer 40 . The two free layers 12 have a voltage-controlled magnetic anisotropy effect. When determining the material of the barrier layer 30, refer to Figures 4 and 6. The material of the barrier layer 30 can be magnesium oxide to improve the tunneling magnetoresistance effect and voltage-controlled magnetic anisotropy provided by the barrier layer 30. The quality of the anisotropy effect is achieved, and the more significant tunneling magnetoresistance effect and voltage-controlled magnetic anisotropy effect are obtained. It should be understood that the method of providing the voltage-controlled magnetic anisotropy effect to the second free layer 12 is not limited to the above-mentioned method through the barrier layer 30 , and other methods may also be adopted. In addition, the material of the barrier layer 30 is not limited to the magnesium oxide shown above. In addition, other materials with barrier properties may also be used.

Referring to Figure 2, when specifically implementing unipolar switching of the resistance state at both ends of the magnetic memory unit, the magnetic memory unit can apply a voltage pulse width to both ends of the magnetic memory unit exceeding the pulse width threshold, based on the second free layer 12 has The voltage-controlled magnetic anisotropy effect causes a unipolar magnetization flip in the perpendicular magnetization directions of the first free layer 11 and the second free layer 12, so that the magnetization direction between the reference layer 40 and the second free layer 12 is in Switching between the parallel state and the anti-parallel state facilitates unipolar switching of the resistance state of the magnetic memory cell. When determining the materials of the first free layer 11 and the second free layer 12, as shown in Figures 4 and 6, the materials of the first free layer 11 and the second free layer 12 can be any one of Co, Fe, and Ni. Materials or alloys containing several materials to facilitate the placement of free layers. When determining the material of the first coupling layer 20 , the material of the first coupling layer 20 may be Ru, Ir, Ta, Mo or W to facilitate the placement of the first coupling layer 20 .

Specifically, referring to Figure 2, when a voltage pulse is just applied to both ends of the magnetic memory cell, the second free layer 12 can switch from perpendicular magnetic anisotropy to in-plane magnetic anisotropy based on its voltage-controlled magnetic anisotropy effect. Magnetic anisotropy (as shown in Figure 2, switching from the initial upward perpendicular magnetic anisotropy to in-plane magnetic anisotropy toward the right). At the same time, in the process of the second free layer 12 switching from perpendicular magnetic anisotropy to in-plane magnetic anisotropy, the second free layer 12 can also drive the perpendicular magnetization direction of the first free layer 11 to oscillate through the first coupling layer 20 . After the voltage pulse width exceeds the pulse width threshold, that is, when the duration of the voltage pulse is greater than the pulse width threshold, the vertical magnetization direction of the first free layer 11 can finally stabilize in the opposite direction of the vertical magnetization direction before oscillation, that is, the first free layer 11 The perpendicular magnetization direction after stabilization is exactly opposite to the perpendicular magnetization direction before oscillation. For example, the initial perpendicular magnetization direction of the first free layer 11 in Figure 2 is upward, and after oscillation and stabilization, its perpendicular magnetization direction is downward. Just opposite to the perpendicular magnetization direction before oscillation. After the voltage pulse width exceeds the pulse width threshold, the magnetization direction of the second free layer 12 can finally stabilize at the in-plane magnetization direction, for example, as shown in FIG. 2 , the magnetization direction finally stabilizes at the in-plane magnetization direction to the right.

Continuing to refer to FIG. 2 , after the voltage pulse width exceeds the pulse width threshold and the voltage pulse is removed, the first free layer 11 can change the magnetization direction of the second free layer 12 from in-plane through the coupling effect of the first coupling layer 20 The magnetization direction is flipped to the same perpendicular magnetization direction as the magnetization direction of the first free layer 11 . That is, the second free layer 12 switches to perpendicular magnetic anisotropy again. As shown in FIG. 2 , the first free layer 11 flips the magnetization direction of the second free layer 12 from the in-plane magnetization direction to the right to a downward perpendicular magnetization direction, which is exactly perpendicular to the stabilized direction of the first free layer 11 . The magnetization directions are the same. Moreover, the vertical magnetization direction of the first free layer 11 and the second free layer 12 after flipping is exactly opposite to the vertical magnetization direction before flipping. That is, before and after the voltage pulse is applied, the magnetization directions of the first free layer 11 and the second free layer 12 change, achieving a deterministic unipolar magnetization flip. Since the resistance state of the magnetic memory cell depends on the relative magnetization direction between the second free layer 12 and the reference layer 40, the magnetization direction of the second free layer 12 changes, while the magnetization direction of the reference layer 40 remains unchanged, thus causing the The relative magnetization direction between the two free layers 12 and the reference layer 40 changes (from a parallel state to an anti-parallel state, or from an anti-parallel state to a parallel state). When a voltage pulse is applied, the initial resistance at both ends of the magnetic memory unit is in a high-resistance state. After the voltage pulse is applied, the resistance at both ends of the magnetic memory unit changes to a low-resistance state. When a voltage pulse is applied, the initial resistance at both ends of the magnetic memory unit is in a low-resistance state. After the voltage pulse is applied, the resistance at both ends of the magnetic memory unit changes to a high-resistance state. Through the above method, it is convenient to drive the perpendicular magnetization directions of the first free layer 11 and the second free layer 12 from the initial direction and unipolarity to the opposite direction.

It should be explained that there is a correlation between the coupling strength of the first coupling layer 20 and the magnitude of the free layer damping coefficient between the two free layers, and the magnitude of the pulse width threshold. When specifically determining the coupling strength of the first coupling layer 20 , the coupling strength of the first coupling layer 20 may be 0.02 to 0.1erg/cm ² . Specifically, the coupling strength of the first coupling layer 20 may be 0.02erg/cm ² or 0.04 erg/cm ² , 0.06erg/cm ² , 0.08erg/cm ² , 0.1erg/cm ² and other values between 0.02 and 0.1erg/cm ² . In addition, the first coupling layer can also be ferromagnetic coupling, the second coupling layer can be antiferromagnetic coupling, and the coupling strength of the second coupling layer 22 is greater than the coupling strength of the first coupling layer 20 , that is, the second coupling layer 22 It is a strong magnetic coupling, while the first coupling layer 20 is a weak magnetic coupling, so that the vertical magnetization direction of the reference layer 40 is not affected by the magnetization directions of the two free layers and maintains a constant vertical magnetization direction. Among them, the free layer damping coefficient composed of the first free layer 11, the first coupling layer 20 and the second free layer 12 can be 0.005 to 0.05. Specifically, the first free layer 11, the first coupling layer 20 and the second free layer The free layer damping coefficient composed of 12 can be 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 and other values between 0.005 and 0.05, which facilitates the process of applying voltage pulses. The free layer 11 eventually stabilizes in the direction opposite to the initial perpendicular magnetization direction, and the second free layer 12 stabilizes in the in-plane magnetization direction. When determining the pulse width threshold, the pulse width threshold can be 1 to 10ns. Specifically, the pulse width threshold can be 1ns, 2ns, 3ns, 4ns, 5ns, 6ns, 7ns, 8ns, 9ns, 10ns, etc., ranging from 1 to 10ns. any value between to reduce the time for applying the voltage pulse.

In addition, referring to FIG. 3 , a magnesium oxide layer 61 may also be stacked on the first free layer 11 , and the magnesium oxide layer 61 and the first coupling layer 20 are arranged on opposite sides of the first free layer 11 . Referring to FIG. 4 , the material of the magnesium oxide layer 61 is magnesium oxide. The magnesium oxide layer 61 can increase the perpendicular magnetic anisotropy of the first free layer 11 so that the first free layer 11 can remain stable after flipping to a certain perpendicular magnetization direction. While enhancing the perpendicular magnetic anisotropy of the first free layer 11 , it is also necessary to make the thickness of the magnesium oxide layer 61 smaller than the thickness of the barrier layer 30 to minimize the resistance of the magnesium oxide layer 61 when a voltage pulse is applied externally. There is less partial pressure, thereby reducing the impact on the rate of change of reluctance. Moreover, it is also necessary to make the thickness of the barrier layer 30 larger to increase the resistance of the barrier layer 30, so that when a voltage pulse is applied externally, more voltage division occurs.

It should be understood that the method of enhancing the perpendicular magnetic anisotropy of the first free layer 11 is not limited to the method of stacking the magnesium oxide layer 61 as shown in FIGS. 3 and 4 . In addition, other methods may also be used. Way. For example, referring to FIGS. 5 and 6 , a heavy metal layer 62 may also be stacked on the first free layer 11 , and the heavy metal layer 62 and the first coupling layer 20 are arranged on opposite sides of the first free layer 11 . The material of the heavy metal layer 62 may be a heavy metal material such as but not limited to W. The heavy metal layer 62 is used to enhance the perpendicular magnetic anisotropy of the first free layer 11 . While enhancing the perpendicular magnetic anisotropy of the first free layer 11, the low resistance characteristic of the heavy metal layer 62 is also utilized to reduce the impact on the magnetoresistance change rate. Moreover, it is possible to utilize the magnetic anisotropy effect of the heavy metal layer 62 which does not have voltage control, so that the heavy metal layer 62 does not affect the unipolar switching of the magnetic memory unit and does not affect the operation of the device. Furthermore, by arranging the heavy metal layer 62, the free layer damping coefficient between the first free layer 11, the first coupling layer 20 and the second free layer 12 can also be improved, which facilitates the control of the overall flip time and flip probability of the magnetic memory array.

In addition, referring to FIGS. 3 to 6 , a bottom electrode 80 and a top electrode 70 can be respectively provided at both ends of the magnetic memory unit to facilitate application of voltage pulses to both ends of the magnetic memory unit and to facilitate reading of the resistance state at both ends of the magnetic memory unit. In a specific arrangement, the bottom electrode 80 can be stacked on the pinning layer 50 , and the second coupling layer 22 and the bottom electrode 80 are arranged on both sides of the pinning layer 50 . The top electrode 70 can be stacked on the magnesium oxide layer 61 or the heavy metal layer 62 , and the top electrode 70 and the first free layer 11 are arranged on both sides of the heavy metal layer 62 behind the magnesium oxide layer 61 . It should be understood that the arrangement manner of the top electrode 70 and the bottom electrode 80 is not limited to the manner shown above, and other arrangement manners may also be adopted.

In the various embodiments shown above, the first coupling layer 20 and the first free layer 11 are added to the magnetic tunnel junction originally composed of the free layer, the barrier layer 30 and the reference layer 40. When the voltage pulse width applied at both ends of the magnetic storage unit exceeds the pulse width threshold, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching, allowing the magnetic storage unit to complete switching between two logical storage devices. Compared with the existing technology that uses pulse current to drive the magnetic storage unit to flip, this application uses pulse voltage to drive the magnetic storage unit to flip. There is almost no need for current pulse driving during operation. As long as the voltage changes, voltage is applied to both ends of the magnetic storage unit. pulse until the voltage pulse width is greater than the pulse width threshold, the resistance state switching of the magnetic memory unit can be quickly completed. That is to say, this application realizes the control of the logical storage state of the magnetic storage unit based entirely on voltage pulses, without the need for current pulse driving, and correspondingly does not require a large-area external circuit for power supply, reducing the area of the power supply circuit, and enabling more magnetic storage units to be installed, thereby having With the advantages of low power consumption and high storage density, it can be used as the basic unit of low-power, high-density non-volatile memory in the future. At the same time, after a voltage pulse is applied for a long enough time, the resistance state of the magnetic memory unit can be switched to unipolarity, eliminating the need to precisely control the pulse width of the voltage pulse and reducing the difficulty of pulse width control.

In addition, an embodiment of the present invention also provides a magnetic memory device. Referring to FIG. 1 , the magnetic memory device includes: a magnetic memory array composed of a plurality of any of the above magnetic memory units, and a pulse voltage generating circuit. Wherein, the pulse voltage generating circuit is used to apply a voltage pulse with a pulse width exceeding a pulse width threshold to both ends of the magnetic memory unit, so that the resistance state at both ends of the magnetic memory unit undergoes unipolar switching. By adding a first coupling layer 20 and a first free layer 11 to the original magnetic tunnel junction composed of a free layer, a barrier layer 30 and a reference layer 40, a voltage pulse width is applied to both ends of the magnetic memory cell. When the pulse width threshold is exceeded, the resistance state at both ends of the magnetic storage unit undergoes unipolar switching, allowing the magnetic storage unit to complete switching between two logical storage devices. Compared with the existing technology that uses pulse current to drive the magnetic storage unit to flip, this application uses pulse voltage to drive the magnetic storage unit to flip. There is almost no need for current pulse driving during operation. As long as the voltage changes, voltage is applied to both ends of the magnetic storage unit. pulse until the voltage pulse width is greater than the pulse width threshold, the resistance state switching of the magnetic memory unit can be quickly completed. That is to say, this application realizes the control of the logical storage state of the magnetic storage unit based entirely on voltage pulses, without the need for current pulse driving, and correspondingly does not require a large-area external circuit for power supply, reducing the area of the power supply circuit, and enabling more magnetic storage units to be installed, thereby having With the advantages of low power consumption and high storage density, it can be used as the basic unit of low-power, high-density non-volatile memory in the future. At the same time, after a voltage pulse is applied for a long enough time, the resistance state of the magnetic memory unit can be switched to unipolarity, eliminating the need to precisely control the pulse width of the voltage pulse and reducing the difficulty of pulse width control.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present invention. All are covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

A magnetic storage unit, characterized by including:

The first free layer, the first coupling layer, the second free layer, the barrier layer and the reference layer are stacked in sequence;

Wherein, the logical storage state of the magnetic storage unit is determined according to the resistance state at both ends of the magnetic storage unit;

And by applying a voltage pulse width exceeding the pulse width threshold to both ends of the magnetic memory unit, the resistance state at both ends of the magnetic memory unit is switched to unipolarity.
The magnetic memory unit of claim 1, wherein the reference layer has perpendicular magnetic anisotropy with a constant perpendicular magnetization direction, and both the first free layer and the second free layer have perpendicular magnetization directions that can be flipped. Perpendicular magnetic anisotropy, and the second free layer also has a voltage-controlled magnetic anisotropy effect;

Based on the voltage-controlled magnetic anisotropy effect, by applying a voltage pulse width exceeding the pulse width threshold to both ends of the magnetic memory cell, the perpendicular magnetization directions of the first free layer and the second free layer are caused to change in a single direction. Polarity magnetization flips.
The magnetic memory unit of claim 2, wherein when a voltage pulse is applied to both ends of the magnetic memory unit, the second free layer changes from a perpendicular magnetic field based on the voltage-controlled magnetic anisotropy effect. The anisotropy is switched to in-plane magnetic anisotropy, and the perpendicular magnetization direction of the first free layer is driven to oscillate through the first coupling layer;

After the voltage pulse width exceeds the pulse width threshold, the perpendicular magnetization direction of the first free layer stabilizes in the opposite direction of the perpendicular magnetization direction before oscillation, and the magnetization direction of the second free layer stabilizes in the in-plane magnetization direction. ;

After the voltage pulse is removed, the first free layer passes through the first coupling layer, flipping the magnetization direction of the second free layer from the in-plane magnetization direction to that of the first free layer. Perpendicular magnetization directions with the same magnetization direction.
The magnetic memory unit according to claim 3, wherein the coupling strength of the first coupling layer is 0.02-0.1erg/cm 2 ;

The free layer damping coefficient composed of the first free layer, the first coupling layer and the second free layer is 0.005-0.05.
The magnetic memory unit of claim 4, wherein the pulse width threshold is 1 to 10 ns.
The magnetic memory unit of claim 1, wherein the barrier layer is used to provide the voltage-controlled magnetic anisotropy effect to the second free layer, and is also used to provide the second free layer with the voltage-controlled magnetic anisotropy effect. layer and the reference layer provide the tunneling magnetoresistance effect.
The magnetic memory unit of claim 6, wherein the barrier layer is made of magnesium oxide.
The magnetic memory unit of claim 6, wherein a magnesium oxide layer is laminated on the first free layer, and the magnesium oxide layer and the first coupling layer are arranged on the first free layer. Opposite sides of the layer;

The magnesium oxide layer is used to increase the perpendicular magnetic anisotropy of the first free layer, and the thickness of the magnesium oxide layer is smaller than the thickness of the barrier layer.
The magnetic memory unit of claim 6, wherein a heavy metal layer is laminated on the first free layer, and the heavy metal layer and the first coupling layer are arranged opposite to the first free layer. both sides of;

The heavy metal layer is used to enhance the perpendicular magnetic anisotropy of the first free layer.
The magnetic storage unit of claim 2, further comprising:

A second coupling layer and a pinning layer disposed on the reference layer are stacked in sequence. The pinning layer passes through the second coupling layer to pin the reference layer to have a perpendicular magnetic direction with a constant perpendicular magnetization direction. opposite sex.
The magnetic memory unit of claim 10, wherein the first coupling layer is ferromagnetic coupling, the second coupling layer is antiferromagnetic coupling, and the coupling strength of the second coupling layer is greater than that of the first coupling layer. the coupling strength.
A magnetic storage device, characterized by including:

A magnetic storage array composed of a plurality of magnetic storage units according to any one of claims 1 to 11;

A pulse voltage generating circuit is used to apply a voltage pulse with a pulse width exceeding a pulse width threshold to both ends of the magnetic storage unit, so that the resistance state at both ends of the magnetic storage unit undergoes unipolar switching.