A magnetic memory cell and a magnetic memory device

Abstract

The application provides 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 stacked. The logic storage state of the magnetic storage unit is determined according to the resistance state of the magnetic storage unit. The resistance state of the magnetic storage unit is switched in a single polarity by applying a voltage pulse with a pulse width exceeding a pulse width threshold to the magnetic storage unit. The application drives the magnetic storage unit to flip by using a pulse voltage, has the advantages of low power consumption and high storage density, does not need to accurately control the pulse width of the voltage pulse, and reduces the difficulty of pulse width control.

Description

Technical Field

[0001] This invention relates to the field of storage technology, and in particular to a magnetic storage unit and a magnetic storage device. Background Technology

[0002] With the rise of connected smart devices, the demand for high-performance data storage and memory technologies is increasing. Current memory technology is dominated by Dynamic Random Access Memory (DRAM). DRAM stores data as electrical charge in capacitors. Data stored in this way can be corrupted by capacitor leakage or discharge. Therefore, DRAM requires periodic charging to protect the data, which significantly increases the power consumption of the memory. Furthermore, the miniaturization of DRAM cells is also constrained by the capacitors; it is necessary to ensure that the amount of charge stored in the capacitors remains unchanged after miniaturization, making it increasingly difficult to increase the storage density of DRAM through miniaturization.

[0003] In recent years, novel non-volatile memory technology has developed rapidly. Non-volatile memory refers to memory whose stored data is preserved even when external power is lost. Non-volatile memory does not require repeated data refresh and has very low static power consumption. Currently, common non-volatile memory cells mainly use variable resistors with two ends, whose resistance characteristics can be changed between high and low resistance states by applying a pulse current. However, this current-driven operation leads to high dynamic power consumption and requires a large external circuit for power supply, resulting in low storage density. Summary of the Invention

[0004] This invention provides a magnetic storage unit and magnetic storage device, which has the advantages of low power consumption and high storage density, and does not require precise control of the pulse width of the voltage pulse, thus reducing the difficulty of pulse width control.

[0005] In a first aspect, the present invention provides a magnetic storage cell comprising: a first free layer, a first coupling layer, a second free layer, a barrier layer, and a reference layer stacked sequentially. The logical storage state of the magnetic storage cell is determined based on the resistance state at both ends of the magnetic storage cell; and by applying a voltage pulse with a width exceeding a pulse width threshold to both ends of the magnetic storage cell, the resistance state at both ends of the magnetic storage cell undergoes a unipolar switching.

[0006] 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 pulse width exceeding a pulse width threshold is applied to the magnetic storage cell, causing a unipolar switch in the resistance state of the magnetic storage cell, thus enabling the magnetic storage cell to switch between two logic storage devices. Compared with the prior art that uses pulse current to drive the magnetic storage cell to flip, this application uses pulse voltage to drive the magnetic storage cell to flip. During operation, almost no current pulse drive is needed. As long as the voltage changes, a voltage pulse is applied to the magnetic storage cell, and the voltage pulse width exceeds the pulse width threshold, the resistance state switch of the magnetic storage cell can be quickly completed. In other words, this application achieves logic storage state control of the magnetic storage cell entirely based on voltage pulses, without the need for current pulse drive. Correspondingly, it also eliminates the need for a large area of ​​external circuitry for power supply, reducing the power supply circuit area and allowing for the placement of more magnetic storage cells. This results in advantages such as low power consumption and high storage density, making it a suitable basic unit for future low-power, high-density non-volatile memories. Meanwhile, after applying a voltage pulse for a sufficiently long time, the resistance state of the magnetic storage cell can undergo unipolar switching, eliminating the need for precise control of the voltage pulse width and reducing the difficulty of pulse width control.

[0007] In one specific embodiment, the reference layer has a constant vertical magnetic anisotropy, and both the first and second free layers have vertical magnetic anisotropy with reversible vertical magnetization directions. The second free layer also exhibits a voltage-controlled magnetic anisotropy effect. Based on this voltage-controlled magnetic anisotropy effect, by applying a voltage pulse exceeding a pulse width threshold to both ends of the magnetic storage cell, the vertical magnetization directions of the first and second free layers undergo unipolar magnetization reversal. This allows the magnetization directions between the reference layer and the second free layer to switch between parallel and antiparallel states, facilitating unipolar switching of the resistance state of the magnetic storage cell.

[0008] In one specific implementation, when a voltage pulse is applied to both ends of the magnetic storage cell, the second free layer switches from perpendicular magnetic anisotropy to in-plane magnetic anisotropy based on the voltage-controlled magnetic anisotropy effect, and drives the perpendicular magnetization direction of the first free layer 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 to 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, through the first coupling layer, flips the magnetization direction of the second free layer from the in-plane magnetization direction to the same perpendicular magnetization direction as the magnetization direction of the first free layer. This facilitates driving the perpendicular magnetization directions of the first and second free layers from their initial directions, unipolar reversal, to opposite directions.

[0009] In one specific implementation, the coupling strength of the first coupling layer is 0.02–0.1 erg / cm. 2 The damping coefficient of the free layer, which consists of the first free layer, the first coupling layer, and the second free layer, is 0.005 to 0.05. This facilitates the application of voltage pulses, ensuring that the first free layer eventually stabilizes in the direction opposite to the initial perpendicular magnetization direction, and the second free layer stabilizes in the in-plane magnetization direction.

[0010] In one specific implementation, the pulse width threshold is 1 to 10 ns to reduce the duration of the applied voltage pulse.

[0011] In one specific implementation, the barrier layer is used to provide a voltage-controlled magnetic anisotropy effect to the second free layer, and also to provide a tunneling magnetoresistance effect to the second free layer and the reference layer, so as to enable the second free layer to have a voltage-controlled magnetic anisotropy effect, and also to facilitate the tunneling magnetoresistance effect between the second free layer, the barrier layer and the reference layer.

[0012] In one specific implementation, the barrier layer is made of magnesium oxide to obtain a more significant tunneling magnetoresistance effect and a voltage-controlled magnetic anisotropy effect.

[0013] In one specific embodiment, a magnesium oxide layer is further stacked on the first free layer, with the magnesium oxide layer and the first coupling layer positioned on opposite sides of the first free layer. The magnesium oxide layer is used to increase the vertical magnetic anisotropy of the first free layer, and the thickness of the magnesium oxide layer is less than the thickness of the barrier layer. While enhancing the vertical magnetic anisotropy of the first free layer, it is necessary to minimize the thickness of the magnesium oxide layer so that the voltage drop is smaller when an external voltage pulse is applied, thereby reducing the impact on the magnetoresistance rate. Furthermore, it is necessary to make the barrier layer thicker to increase its resistance, resulting in a larger voltage drop when an external voltage pulse is applied.

[0014] In one specific embodiment, a heavy metal layer is further stacked on the first free layer, with the heavy metal layer and the first coupling layer positioned on opposite sides of the first free layer. The heavy metal layer enhances the vertical magnetic anisotropy of the first free layer. While enhancing the vertical magnetic anisotropy of the first free layer, the low resistance of the heavy metal layer reduces its impact on the magnetoresistance rate. Furthermore, the absence of voltage-controlled magnetic anisotropy in the heavy metal layer ensures that it does not affect the unipolar switching of the magnetic storage cells and thus does not affect device operation. Moreover, by incorporating the heavy metal layer, the free layer damping coefficient between the first free layer, the first coupling layer, and the second free layer can be increased, facilitating the control of the overall flip time and flip probability of the magnetic storage array.

[0015] In one specific embodiment, the magnetic storage cell further includes a second coupling layer and a pinning layer sequentially stacked on the reference layer. The pinning layer, through the second coupling layer, pins the reference layer to have a vertical magnetic anisotropy with a constant vertical magnetization direction, facilitating the pinning of the vertical magnetization direction of the reference layer.

[0016] In one specific implementation, the first coupling layer is ferromagnetic coupled and the second coupling layer is antiferromagnetic coupled. The coupling strength of the second coupling layer is greater than that of the first coupling layer, so that the vertical magnetization direction of the reference layer is not affected by the magnetization directions of the two free layers, and remains a constant vertical magnetization direction.

[0017] In one specific implementation, the materials of the first coupling layer and the second coupling layer are both Ru, Ir, Ta, Mo or W, which facilitates the setting of two coupling layers.

[0018] In one specific embodiment, the material of the pinning layer is FeNi, FePd, CoNi, FePt, or CoPt, which facilitates the setting of the pinning layer.

[0019] In one specific embodiment, the first free layer, the second free layer, and the reference layer are made of any one of Co, Fe, or Ni, or an alloy containing several of these materials, which facilitates the setting of the free layer and the reference layer.

[0020] Secondly, the present invention also provides a magnetic storage device, comprising: a magnetic storage array composed of a plurality of magnetic storage cells as described above, and a pulse voltage generating circuit. The pulse voltage generating circuit applies a voltage pulse with a pulse width exceeding a pulse width threshold to the two ends of the magnetic storage cell, causing a unipolar switch in the resistance state of the magnetic storage cell. 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, the unipolar switch in the resistance state of the magnetic storage cell is achieved by applying a voltage pulse with a width exceeding the pulse width threshold, enabling the magnetic storage cell to switch between two logic storage devices. Compared with the prior art that uses pulse current to drive the magnetic storage cell to flip, this application uses pulse voltage to drive the magnetic storage cell to flip. During operation, almost no current pulse is required; as long as the voltage changes, a voltage pulse is applied to the two ends of the magnetic storage cell, and the voltage pulse width exceeds the pulse width threshold, the resistance state switch of the magnetic storage cell can be quickly completed. This application achieves logical storage state control of magnetic storage cells entirely based on voltage pulses, eliminating the need for current pulse driving and consequently reducing the need for large external power supply circuits. This reduces the power supply circuit area, allowing for the inclusion of more magnetic storage cells, resulting in advantages such as low power consumption and high storage density. It can serve as the basic unit for future low-power, high-density non-volatile memories. Furthermore, after applying a voltage pulse for a sufficiently long time, the resistance state of the magnetic storage cell can undergo unipolar switching, eliminating the need for precise control of the voltage pulse width and reducing the difficulty of pulse width control. Attached Figure Description

[0021] Figure 1 This is a structural cross-sectional view of a magnetic storage cell provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram illustrating the changes in magnetization state and barrier structure after applying a voltage pulse, as provided in an embodiment of the present invention.

[0023] Figure 3 This is a cross-sectional view of another magnetic storage cell provided in an embodiment of the present invention;

[0024] Figure 4 This is a cross-sectional view of another magnetic storage cell provided in an embodiment of the present invention;

[0025] Figure 5 This is a cross-sectional view of another magnetic storage cell provided in an embodiment of the present invention;

[0026] Figure 6 This is a cross-sectional view of another magnetic storage cell provided in an embodiment of the present invention.

[0027] Figure label:

[0028] 11-First Free Layer 12-Second Free Layer 21-First Coupling Layer

[0029] 22-Second coupling layer; 30-Barrier layer; 40-Reference layer; 50-Pinning layer

[0030] 61 - Magnesium oxide layer; 62 - Heavy metal layer; 70 - Top electrode; 80 - Bottom electrode Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] To facilitate understanding of the magnetic storage unit provided in the embodiments of the present invention, the application scenario of the magnetic storage unit provided in the embodiments of the present invention will be described first. This magnetic storage unit is used as a storage bit in a magnetic storage device. The magnetic storage unit will then be described in detail with reference to the accompanying drawings.

[0033] refer to Figure 1 and Figure 2 The magnetic storage cell provided in this embodiment of the 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 stacked sequentially. The logical storage state of the magnetic storage cell is determined based on the resistance state at both ends of the magnetic storage cell; and by applying a voltage pulse with a width exceeding a pulse width threshold to both ends of the magnetic storage cell, the resistance state at both ends of the magnetic storage cell undergoes a unipolar switching.

[0034] In the above scheme, 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 unipolar switching of the resistance state at both ends of the magnetic storage cell is achieved by applying a voltage pulse width exceeding a pulse width threshold, thus enabling the magnetic storage cell to switch between two logic storage devices. Compared with the prior art that uses pulse current to drive the magnetic storage cell to flip, this application uses pulse voltage to drive the magnetic storage cell to flip. During operation, almost no current pulse drive is required. As long as the voltage changes, a voltage pulse is applied to both ends of the magnetic storage cell, and the voltage pulse width exceeds the pulse width threshold, the resistance state switching of the magnetic storage cell can be quickly completed. In other words, this application achieves logic storage state control of the magnetic storage cell entirely based on voltage pulses, without the need for current pulse drive. Correspondingly, it also eliminates the need for a large area of ​​external circuitry for power supply, reducing the power supply circuit area and allowing for the placement of more magnetic storage cells. This results in advantages such as low power consumption and high storage density, making it a suitable basic unit for future low-power, high-density non-volatile memories. Furthermore, after applying a voltage pulse for a sufficiently long time, the resistance state of the magnetic storage cell can undergo unipolar switching, eliminating the need for precise control of the voltage pulse width and reducing the difficulty of pulse width control. The following sections, with reference to the accompanying drawings, provide a detailed description of each of the above structures.

[0035] When setting it up, refer to Figure 1 The structure consists of a first free layer 11, a first coupling layer 20, a second free layer 12, a barrier layer 30, and a reference layer 40, stacked sequentially 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 following... Figure 1Besides the top-to-bottom stacking shown, 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 be stacked sequentially from bottom to top. The second free layer 12, the barrier layer 30, and the reference layer 40 form a magnetic tunnel junction structure, meaning the magnetization direction between the second free layer 12 and the reference layer 40 can be flipped between parallel and antiparallel states, thereby changing the resistance state at both ends of the magnetic storage cell. The barrier layer 30 provides a tunneling magnetoresistance effect to the second free layer 12 and the reference layer 40, facilitating the implementation of the tunneling magnetoresistance effect between them. Specifically, when the magnetization direction between the second free layer 12 and the reference layer 40 is parallel (i.e., their magnetization directions are the same), the resistance state at both ends of the magnetic storage cell is in a low-resistance state. When the magnetization directions between the second free layer 12 and the reference layer 40 are antiparallel, meaning their magnetization directions are exactly opposite, the resistance state at both ends of the magnetic storage cell is in a high-resistance state. The magnetic storage cell uses these high-resistance and low-resistance states to characterize its two logical storage states, respectively. In other words, the logical storage state of the storage cell is determined by the resistance state at both ends of the magnetic storage cell, thereby enabling data reading and writing.

[0036] When setting the reference layer 40, the reference layer 40 has a constant perpendicular magnetic anisotropy, that is, the perpendicular magnetization direction within the reference layer 40 can be as follows: Figure 1 The direction shown remains constant upward. Specifically, as... Figure 1 As shown, a second coupling layer 22 and a pinning layer 50 can be sequentially stacked on the side of the reference layer 40 facing away from the barrier layer 30. The pinning layer 50, through the second coupling layer 22, pins the reference layer 40 to have a vertical magnetic anisotropy with a constant vertical magnetization direction, facilitating the pinning of the vertical magnetization direction of the reference layer 40. When determining the material of the reference layer 40, the reference... Figure 4 and Figure 6 The reference layer 40 can be made of any one of Co, Fe, or Ni, or an alloy containing several of these materials, facilitating the placement of the reference layer 40. When determining the material of the pinning layer 50, the reference... Figure 4 and Figure 6 The material of the pinning layer 50 can be FeNi, FePd, CoNi, FePt, or CoPt, which facilitates the placement of the pinning layer 50. When determining the material of the second coupling layer 22, refer to... Figure 4 and Figure 6 The material of the second coupling layer 22 can be Ru, Ir, Ta, Mo, or W, which facilitates the placement of the second coupling layer 22. It should be understood that the method of pinning the reference layer 40 in the vertical magnetization direction is not limited to the method shown above; other pinning methods can also be used.

[0037] When setting the first free layer 11, the first coupling layer 20, and the second free layer 12 as described above, such as Figure 1 As shown, 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 the first coupling layer 20. Both the first free layer 11 and the second free layer 12 have vertical magnetic anisotropy, meaning the vertical magnetization direction can be reversed. Figure 1 The image shows a flipping motion between upward and downward. Furthermore, the second free layer 12 also possesses a voltage-controlled magnetic anisotropy effect, specifically provided 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, facilitating the second free layer 12 to possess this voltage-controlled magnetic anisotropy effect. When determining the material of the barrier layer 30, the reference layer... Figure 4 and Figure 6 The barrier layer 30 can be made of magnesium oxide to improve the quality of the tunneling magnetoresistance effect and voltage-controlled magnetic anisotropy effect provided by the barrier layer 30, thereby obtaining a more significant tunneling magnetoresistance effect and voltage-controlled magnetic anisotropy effect. It should be understood that the method of providing voltage-controlled magnetic anisotropy effect to the second free layer 12 is not limited to the method described above using the barrier layer 30; other methods can also be used. Furthermore, the material of the barrier layer 30 is not limited to magnesium oxide as shown above; other materials with barrier properties can also be used.

[0038] refer to Figure 2 In the specific implementation of unipolar switching of the resistance state at both ends of the magnetic storage cell, the magnetic storage cell can be unipolarly magnetized by applying a voltage pulse width exceeding the pulse width threshold to both ends. Based on the voltage-controlled magnetic anisotropy effect of the second free layer 12, the perpendicular magnetization directions of the first free layer 11 and the second free layer 12 are reversed, thereby switching the magnetization direction between the reference layer 40 and the second free layer 12 between parallel and antiparallel states, facilitating unipolar switching of the resistance state of the magnetic storage cell. When determining the materials of the first free layer 11 and the second free layer 12, such as... Figure 4 and Figure 6 As shown, the materials of the first free layer 11 and the second free layer 12 can be any one of Co, Fe, and Ni, or an alloy containing several materials, which facilitates the setting of the free layers. When determining the material of the first coupling layer 20, the material of the first coupling layer 20 can be Ru, Ir, Ta, Mo, or W, which facilitates the setting of the first coupling layer 20.

[0039] For details, please refer to Figure 2 When a voltage pulse is applied to both ends of a magnetic storage cell, the second free layer 12, based on its voltage-controlled magnetic anisotropy effect, can switch from perpendicular magnetic anisotropy to in-plane magnetic anisotropy (e.g., ...). Figure 2 The diagram shows the transition from an initial upward perpendicular magnetic anisotropy to an in-plane rightward magnetic anisotropy. Simultaneously, during this transition, the second free layer 12, through the first coupling layer 20, can also cause the perpendicular magnetization direction of the first free layer 11 to oscillate. When the voltage pulse width exceeds the pulse width threshold (i.e., the duration of the voltage pulse is greater than the pulse width threshold), the perpendicular magnetization direction of the first free layer 11 can eventually stabilize in the opposite direction to the perpendicular magnetization direction before oscillation. In other words, the stabilized perpendicular magnetization direction of the first free layer 11 is exactly opposite to the perpendicular magnetization direction before oscillation. For example... Figure 2 The initial vertical magnetization direction of the first free layer 11 is upward, but after oscillation and stabilization, its vertical magnetization direction is downward, exactly opposite to the vertical magnetization direction before oscillation. After the voltage pulse width exceeds the pulse width threshold, the magnetization direction of the second free layer 12 can eventually stabilize in the in-plane magnetization direction, for example... Figure 2 The final stability shown is in the in-plane magnetization direction to the right.

[0040] Continue to refer to Figure 2 However, after the voltage pulse width exceeds the pulse width threshold, upon removal of the voltage pulse, the first free layer 11, through the coupling effect of the first coupling layer 20, can flip the magnetization direction of the second free layer 12 from the in-plane magnetization direction to a perpendicular magnetization direction, the same as the magnetization direction of the first free layer 11. That is, the second free layer 12 re-switches to perpendicular magnetic anisotropy. Figure 2As shown, the first free layer 11 flips the magnetization direction of the second free layer 12 from an in-plane to right-facing in-plane magnetization direction to a downward vertical magnetization direction, which is exactly the same as the vertical magnetization direction of the first free layer 11 after stabilization. Furthermore, the vertical magnetization directions of the first free layer 11 and the second free layer 12 after the flip are exactly opposite to their original vertical magnetization directions. 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 reversal. Since the resistance state of the magnetic storage cell depends on the relative magnetization direction between the second free layer 12 and the reference layer 40, the change in the magnetization direction of the second free layer 12 while the magnetization direction of the reference layer 40 remains unchanged will cause a change in the relative magnetization direction between the second free layer 12 and the reference layer 40 (from parallel to antiparallel, or from antiparallel to parallel). When the initial resistance at both ends of the magnetic storage cell is high before the voltage pulse is applied, the resistance at both ends of the magnetic storage cell will change to low resistance after the voltage pulse is applied. Before a voltage pulse is applied, the initial resistance across the magnetic storage cell is low. After the voltage pulse is applied, the resistance across the magnetic storage cell changes to high resistance. In this way, it is easy to drive the vertical magnetization direction of the first free layer 11 and the second free layer 12 to reverse from the initial direction to the opposite direction.

[0041] 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. Specifically, the coupling strength of the first coupling layer 20 can be determined to be 0.02–0.1 erg / cm. 2 Specifically, the coupling strength of the first coupling layer 20 can be 0.02 erg / cm. 2 0.04erg / cm 2 0.06erg / cm 2 0.08erg / cm 2 0.1erg / cm 2 The values ​​range from 0.02 to 0.1 erg / cm. 2Any value between these values. Alternatively, the first coupling layer can be ferromagnetically coupled, the second coupling layer can be antiferromagnetically coupled, and the coupling strength of the second coupling layer 22 can be greater than the coupling strength of the first coupling layer 20. That is, the second coupling layer 22 is strongly magnetically coupled, while the first coupling layer 20 is weakly magnetically coupled, so that the vertical magnetization direction of the reference layer 40 is not affected by the magnetization directions of the two free layers, and remains a constant vertical magnetization direction. The damping coefficient of the free layer composed of the first free layer 11, the first coupling layer 20, and the second free layer 12 can be between 0.005 and 0.05. Specifically, the damping coefficient can be any value between 0.005 and 0.05, such as 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, or 0.050. This ensures that during the application of the voltage pulse, the first 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 between 1 and 10 ns. Specifically, the pulse width threshold can be any value between 1 and 10 ns, such as 1 ns, 2 ns, 3 ns, 4 ns, 5 ns, 6 ns, 7 ns, 8 ns, 9 ns, or 10 ns, to reduce the duration of the applied voltage pulse.

[0042] Additionally, refer to Figure 3 A magnesium oxide layer 61 may also be stacked on the first free layer 11, with the magnesium oxide layer 61 and the first coupling layer 20 positioned on opposite sides of the first free layer 11. (See reference) Figure 4 The magnesium oxide layer 61 is made of magnesium oxide. The magnesium oxide layer 61 increases the perpendicular magnetic anisotropy of the first free layer 11, facilitating its stability after it flips to a certain perpendicular magnetization direction. While enhancing the perpendicular magnetic anisotropy of the first free layer 11, the thickness of the magnesium oxide layer 61 needs to be less than the thickness of the barrier layer 30 to minimize its resistance, resulting in less voltage division when an external voltage pulse is applied, thus reducing the impact on the magnetoresistance rate. Furthermore, the thickness of the barrier layer 30 needs to be relatively large to increase its resistance, resulting in more voltage division when an external voltage pulse is applied.

[0043] It should be understood that the methods for enhancing the vertical magnetic anisotropy of the first free layer 11 are not limited to... Figure 3 and Figure 4 The method shown involves stacking magnesium oxide layers 61; other methods can also be used. For example, see reference... Figure 5 and Figure 6A heavy metal layer 62 can also be stacked on the first free layer 11, with the heavy metal layer 62 and the first coupling layer 20 positioned on opposite sides of the first free layer 11. The material of the heavy metal layer 62 can be a heavy metal material such as, but not limited to, W. The heavy metal layer 62 is used to enhance the vertical magnetic anisotropy of the first free layer 11. While enhancing the vertical magnetic anisotropy of the first free layer 11, the low resistance of the heavy metal layer 62 also reduces the impact on the rate of change of magnetoresistance. Furthermore, the absence of voltage-controlled magnetic anisotropy effect in the heavy metal layer 62 ensures that it does not affect the unipolar switching of the magnetic storage cells and thus does not affect the operation of the device. Moreover, by setting 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 be increased, facilitating the control of the overall flip time and flip probability of the magnetic storage array.

[0044] Additionally, refer to Figures 3-6 A bottom electrode 80 and a top electrode 70 can be respectively set at both ends of the magnetic storage cell to facilitate the application of voltage pulses to both ends of the magnetic storage cell and to facilitate the reading of the resistance state at both ends of the magnetic storage cell. Specifically, the bottom electrode 80 can be stacked on the pinning layer 50, with the second coupling layer 22 and the bottom electrode 80 positioned on opposite 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, with the top electrode 70 and the first free layer 11 positioned on opposite sides of the heavy metal layer 62 after the magnesium oxide layer 61. It should be understood that the arrangement of the top electrode 70 and the bottom electrode 80 is not limited to the methods shown above; other arrangements can also be used.

[0045] The various embodiments described above, 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, allow the magnetic storage cell to switch between two logic storage devices by applying a voltage pulse width exceeding a pulse width threshold across its terminals. Compared to the prior art that uses pulsed current to drive the magnetic storage cell switching, this application uses pulsed voltage to drive the magnetic storage cell switching. During operation, almost no current pulse drive is required; as long as the voltage changes, a voltage pulse is applied across the magnetic storage cell, and the voltage pulse width exceeds the pulse width threshold, the resistance state switching of the magnetic storage cell can be quickly completed. In other words, this application achieves logic storage state control of the magnetic storage cell entirely based on voltage pulses, without the need for current pulse drive. Consequently, it also eliminates the need for a large external circuit for power supply, reducing the power supply circuit area and allowing for the placement of more magnetic storage cells. This results in advantages such as low power consumption and high storage density, making it a suitable basic unit for future low-power, high-density non-volatile memories. Meanwhile, after applying a voltage pulse for a sufficiently long time, the resistance state of the magnetic storage cell can undergo unipolar switching, eliminating the need for precise control of the voltage pulse width and reducing the difficulty of pulse width control.

[0046] In addition, embodiments of the present invention also provide a magnetic storage device, see reference. Figure 1The magnetic storage device includes a magnetic storage array composed of multiple magnetic storage cells of any of the above types, and a pulse voltage generation circuit. The pulse voltage generation circuit applies a voltage pulse with a pulse width exceeding a pulse width threshold to the two ends of the magnetic storage cell, causing a unipolar switch in the resistance state of the magnetic storage cell. 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, the unipolar switch in the resistance state of the magnetic storage cell is achieved by applying a voltage pulse with a width exceeding the pulse width threshold, allowing the magnetic storage cell to switch between two logic storage devices. Compared to the prior art that uses pulse current to drive the magnetic storage cell switching, this application uses pulse voltage to drive the magnetic storage cell switching. During operation, almost no current pulse is needed; as long as the voltage changes, a voltage pulse is applied to the two ends of the magnetic storage cell, and the voltage pulse width exceeds the pulse width threshold, the resistance state switching of the magnetic storage cell can be quickly completed. This application achieves logical storage state control of magnetic storage cells entirely based on voltage pulses, eliminating the need for current pulse driving and consequently reducing the need for large external power supply circuits. This reduces the power supply circuit area, allowing for the inclusion of more magnetic storage cells, resulting in advantages such as low power consumption and high storage density. It can serve as the basic unit for future low-power, high-density non-volatile memories. Furthermore, after applying a voltage pulse for a sufficiently long time, the resistance state of the magnetic storage cell can undergo unipolar switching, eliminating the need for precise control of the voltage pulse width and reducing the difficulty of pulse width control.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A magnetic storage unit, characterized in that, include: The first free layer, the first coupling layer, the second free layer, the barrier layer, and the reference layer are stacked in sequence. The logical storage state of the magnetic storage unit is determined based on the resistance state at both ends of the magnetic storage unit. Furthermore, 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 a unipolar switch. The second free layer also has a voltage-controlled magnetic anisotropy effect; When a voltage pulse is applied to both ends of the magnetic storage cell, the second free layer switches from vertical magnetic anisotropy to in-plane magnetic anisotropy based on the voltage-controlled magnetic anisotropy effect, and drives the vertical magnetization direction of the first free layer to oscillate through the first coupling layer. After the voltage pulse width exceeds the pulse width threshold, the vertical magnetization direction of the first free layer stabilizes in the opposite direction to the vertical 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, through the first coupling layer, flips the magnetization direction of the second free layer from the in-plane magnetization direction to a perpendicular magnetization direction that is the same as the magnetization direction of the first free layer; The first coupling layer is ferromagnetic, and the coupling strength of the first coupling layer is 0.02~0.1 erg / cm. 2 ; The damping coefficient of the free layer composed of the first free layer, the first coupling layer, and the second free layer is 0.005~0.

05.

2. The magnetic storage unit as described in claim 1, characterized in that, The reference layer has a constant vertical magnetic anisotropy perpendicular to the magnetization direction, while both the first and second free layers have a vertical magnetic anisotropy perpendicular to the magnetization direction that can be reversed. 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 storage cell, the vertical magnetization directions of the first and second free layers undergo unipolar magnetization reversal.

3. The magnetic storage unit as described in claim 1, characterized in that, The pulse width threshold is 1~10ns.

4. The magnetic storage unit as described in claim 1, characterized in that, The barrier layer is used to provide the voltage-controlled magnetic anisotropy effect to the second free layer, and also to provide the tunneling magnetoresistance effect to the second free layer and the reference layer.

5. The magnetic storage unit as described in claim 4, characterized in that, The barrier layer is made of magnesium oxide.

6. The magnetic storage unit as described in claim 4, characterized in that, A magnesium oxide layer is also stacked 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 vertical magnetic anisotropy of the first free layer, and the thickness of the magnesium oxide layer is less than the thickness of the barrier layer.

7. The magnetic storage unit as claimed in claim 4, characterized in that, A heavy metal layer is also stacked 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 vertical magnetic anisotropy of the first free layer.

8. The magnetic storage unit as claimed in claim 2, characterized in that, Also includes: A second coupling layer and a pinning layer are sequentially stacked on the reference layer. The pinning layer, through the second coupling layer, pins the reference layer to have a vertical magnetic anisotropy with a constant vertical magnetization direction.

9. The magnetic storage unit as claimed in claim 8, characterized in that, The second coupling layer is an antiferromagnetic coupling layer, and the coupling strength of the second coupling layer is greater than that of the first coupling layer.

10. A magnetic storage device, characterized in that, include: A magnetic storage array comprising a plurality of magnetic storage cells as described in any one of claims 1 to 9; 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, causing a unipolar switching of the resistance state at both ends of the magnetic storage unit.

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