Magnetic memory cell and SOT-MRAM memory

Abstract

The invention discloses a magnetic memory unit and an SOT-MRAM memory, which are applied to the technical field of MRAM memories, and comprise at least one group of differential bits and an auxiliary magnetic structure, the differential bit includes: a spin orbit moment provision line; the two magnetic tunnel junctions are positioned on one side of the spin orbit moment providing line; the differential bit has a first direction parallel to the axis of the spin orbit moment providing line and an initial magnetization direction perpendicular to the first direction; the auxiliary magnetic structure provides a bias magnetic field for the two magnetic tunnel junctions in the same differential bit, and the bias magnetic field has a component in the first direction and a component in the initial magnetization direction; the component directions of the two bias magnetic fields along the initial magnetization direction are the same, and the component directions of the two bias magnetic fields along the first direction are opposite. Initialization can be completed only through one-time initial magnetization in the initial magnetization direction, and meanwhile the reliable writing-in problem and the high-speed reading problem of the perpendicularly magnetized MTJ zero magnetic field are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of MRAM memory, and in particular to a magnetic storage unit and a SOT-MRAM memory. Background Art

[0002] SOT-MTJ (spin-orbit torque magnetic tunnel junction) devices are one of the core structural types of MRAM (Magnetoresistive Random Access Memory) products. Compared with STT-MTJ (Spin Transfer Torque magnetic tunnel junction) devices, SOT-MTJ devices have the characteristics of fast writing speed, unlimited erasing and read-write separation. The two obvious structural features of SOT-MTJ devices are: the SOT (spin-orbit torque) track layer provides an independent channel for the write current, read-write separation; secondly, a horizontal magnetic field needs to be applied along the current direction to achieve deterministic flipping of the vertical free layer, and the flipping polarity depends on the relative direction of the horizontal magnetic field acting on the free layer and the current.

[0003] In the manufacturing of traditional SOT-MRAM (spin-orbit torque Magnetoresistive Random Access Memory), the MTJ (magnetic tunnel junction) uses a top-pinned structure, and the integration of spin-orbit torque materials and high TMR (Tunnel Magneto Resistance) materials is difficult. The TMR ratio is generally not high, and can only reach about 100% at present, which directly affects the read and write speed of SOT-MRAM. For this problem, differential bits are an effective solution. However, in the prior art, the auxiliary magnetic layer needs to be initially magnetized twice; and the auxiliary magnetic layer obtains different switching magnetic fields by adopting different aspect ratios, and the operating window is limited. Therefore, how to provide a reliable, easy-to-operate, high-speed read and write SOT-MRAM memory is an urgent problem that technicians in this field need to solve. Summary of the invention

[0004] The purpose of the present invention is to provide a SOT-MRAM differential bit design scheme based on perpendicular magnetization, which can simultaneously solve the problem of reliable writing and high-speed reading in zero magnetic field.

[0005] In order to solve the above technical problems, the present invention provides a magnetic storage unit, comprising at least one set of differential bits and an auxiliary magnetic structure; the differential bits include:

[0006] The spin-orbit moment provides the line;

[0007] Two magnetic tunnel junctions located on one side of the spin-orbit moment providing line; the differential bit has a first direction parallel to the axis of the spin-orbit moment providing line, and an initial magnetization direction perpendicular to the first direction;

[0008] The auxiliary magnetic structure provides a bias magnetic field to two magnetic tunnel junctions in the same differential bit, respectively. The bias magnetic field has a component along the first direction and a component along the initial magnetization direction. The components of the two bias magnetic fields along the initial magnetization direction are in the same direction, and the components of the two bias magnetic fields along the first direction are in opposite directions.

[0009] Optionally, a separation layer is provided on the surface of the magnetic tunnel junction facing away from the spin-orbit moment providing line;

[0010] The auxiliary magnetic structure includes an auxiliary magnetic layer with an in-plane easy axis located on the surface of the separation layer facing away from the spin-orbit moment providing line; the magnetic moment of the auxiliary magnetic layer has an angle with the first direction, so that the components of the magnetic moments of the two auxiliary magnetic layers corresponding to the same differential bit are opposite in direction along the first direction and the components are the same in direction along the second direction; the second direction is a direction perpendicular to the first direction in a horizontal plane.

[0011] Optionally, the included angles between the two auxiliary magnetic layers corresponding to the same differential bit are complementary angles.

[0012] Optionally, the angle between the auxiliary magnetic layer corresponding to the same differential bit and the first direction ranges from 20° to 70°, including endpoint values; the angle between the other auxiliary magnetic layer and the first direction ranges from 110° to 160°, including endpoint values.

[0013] Optionally, the auxiliary magnetic structure further includes a pinning layer located on the surface of the auxiliary magnetic layer on a side facing away from the spin-orbit moment providing line; the magnetic moment direction of the pinning layer corresponds to the magnetic moment direction of the auxiliary magnetic layer in contact with it.

[0014] Optionally, the auxiliary magnetic structure includes an auxiliary magnetic body, and the auxiliary magnetic body provides the bias magnetic field to the two magnetic tunnel junctions in the same differential bit.

[0015] Optionally, the auxiliary magnetic body is located on a side of the spin-orbit moment providing line facing away from the magnetic tunnel junction, and the auxiliary magnetic body has perpendicular magnetic anisotropy.

[0016] Optionally, the auxiliary magnetic body is located in the middle of the two magnetic tunnel junctions of the same differential bit.

[0017] Optionally, two groups of differential bits are included, the spin-orbit moment providing lines of the two groups of differential bits are parallel, the auxiliary magnetic body is located between the two groups of differential bits, and one auxiliary magnetic body provides the bias magnetic field to the two groups of differential bits, a total of four magnetic tunnel junctions.

[0018] The present invention also provides a SOT-MRAM memory, wherein the SOT-MRAM memory comprises the magnetic storage unit as described in any one of the above items.

[0019] A magnetic storage unit provided by the present invention comprises at least one group of differential bits and an auxiliary magnetic structure; the differential bit comprises: a spin-orbit moment providing line; two magnetic tunnel junctions located on one side of the spin-orbit moment providing line; the differential bit has a first direction parallel to the axis of the spin-orbit moment providing line, and an initial magnetization direction perpendicular to the first direction; the auxiliary magnetic structure provides a bias magnetic field to the two magnetic tunnel junctions in the same differential bit, respectively, the bias magnetic field has a component along the first direction and a component along the initial magnetization direction; the components of the two bias magnetic fields along the initial magnetization direction are in the same direction, and the components of the two bias magnetic fields along the first direction are in opposite directions.

[0020] Since the bias magnetic field provided by the auxiliary magnetic structure to the magnetic tunnel junction has components in both the first direction and the initial magnetization direction, and the components of the bias magnetic field along the first direction of the two magnetic tunnel junctions in the same differential bit are opposite, and the components along the initial magnetization direction are the same, it is only necessary to receive an initial magnetization along the initial magnetization direction once to make the stray field of the bias magnetic field in the opposite direction of the horizontal component of the free layers of the two magnetic tunnel junctions, complete the initialization, and then solve the reliable writing problem and high-speed reading problem of the perpendicularly magnetized MTJ zero magnetic field at the same time.

[0021] The present invention also provides a SOT-MRAM memory, which also has the above-mentioned beneficial effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic structural diagram of a magnetic storage unit provided by an embodiment of the present invention;

[0024] Figure 2 A schematic structural diagram of a first specific magnetic storage unit provided by an embodiment of the present invention;

[0025] Figure 3 for Figure 2 A schematic diagram of a top view structure;

[0026] Figure 4 A schematic structural diagram of a second specific magnetic storage unit provided by an embodiment of the present invention;

[0027] Figure 5 A schematic structural diagram of a third specific magnetic storage unit provided by an embodiment of the present invention;

[0028] Figure 6 A schematic structural diagram of a fourth specific magnetic storage unit provided by an embodiment of the present invention;

[0029] Figure 7 for Figure 6 Schematic diagram of the side structure.

[0030] In the figure: 1. spin-orbit moment providing line, 2. magnetic tunnel junction, 21. free layer, 22. barrier layer, 23. fixed layer, 24. separation layer, 3. auxiliary magnetic structure, 31. auxiliary magnetic layer, 32. pinned layer, 33. auxiliary magnetic body. DETAILED DESCRIPTION

[0031] The core of the present invention is to provide a magnetic storage unit. In the prior art, the SOT-MRAM device based on differential bits needs to be initially magnetized twice before writing information; and the auxiliary magnetic layer obtains different switching magnetic fields by adopting different aspect ratios, and the operation window is limited.

[0032] The present invention provides a magnetic storage unit, which includes at least one group of differential bits and an auxiliary magnetic structure; the differential bit includes: a spin-orbit moment providing line; two magnetic tunnel junctions located on one side of the spin-orbit moment providing line; the differential bit has a first direction parallel to the axis of the spin-orbit moment providing line, and an initial magnetization direction perpendicular to the first direction; the auxiliary magnetic structure provides a bias magnetic field to the two magnetic tunnel junctions in the same differential bit, respectively, the bias magnetic field has a component along the first direction and a component along the initial magnetization direction; the components of the two bias magnetic fields along the initial magnetization direction are in the same direction, and the components of the two bias magnetic fields along the first direction are in opposite directions.

[0033] Since the bias magnetic field provided by the auxiliary magnetic structure to the magnetic tunnel junction has components in both the first direction and the initial magnetization direction, and the components of the bias magnetic field along the first direction of the two magnetic tunnel junctions in the same differential bit are opposite, and the components along the initial magnetization direction are the same, it is only necessary to receive an initial magnetization along the initial magnetization direction once to make the stray field of the bias magnetic field in the opposite direction of the horizontal component of the free layers of the two magnetic tunnel junctions, complete the initialization, and then solve the reliable writing problem and high-speed reading problem of the perpendicularly magnetized MTJ zero magnetic field at the same time.

[0034] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a magnetic storage unit provided by an embodiment of the present invention.

[0036] See also Figure 1 In an embodiment of the present invention, a magnetic storage unit includes at least one group of differential bits and an auxiliary magnetic structure 3; the differential bit includes: a spin-orbit moment providing line 1; two magnetic tunnel junctions 2 located on one side of the spin-orbit moment providing line 1; the magnetic tunnel junction 2 includes a free layer 21, a barrier layer 22, and a fixed layer 23 arranged in sequence along a direction from the surface of the spin-orbit moment providing line 1 to a side away from the spin-orbit moment providing line 1; the differential bit has a first direction parallel to the axis of the spin-orbit moment providing line 1, and an initial magnetization direction perpendicular to the first direction; the auxiliary magnetic structure 3 provides a bias magnetic field to the two magnetic tunnel junctions 2 in the same differential bit, respectively, and the bias magnetic field has a component along the first direction and a component along the initial magnetization direction; the components of the two bias magnetic fields along the initial magnetization direction are in the same direction, and the components of the two bias magnetic fields along the first direction are in opposite directions.

[0037] The differential bit is a basic unit for storing differential signals, and the differential bit includes a spin-orbit torque providing line 1, and two magnetic tunnel junctions 2 located on one side of the spin-orbit torque providing line 1. The orbital torque providing line is a SOT providing line, and the current flowing through the spin-orbit torque providing line 1 can induce a torque to drive the magnetization reversal of the free layer 21. The material of the spin-orbit torque providing line 1 needs to be a material with a spin-orbit torque effect, including: heavy metals, BiSe alloys, antiferromagnetic or two-dimensional materials, etc. The specific material of the spin-orbit torque providing line 1 is not specifically limited here.

[0038] Two magnetic tunnel junctions 2 are arranged on one side of the spin-orbit torque providing line 1, forming a differential bit. When writing data, the two magnetic tunnel junctions 2 in a differential bit need to write opposite information. The magnetic tunnel junction 2 includes a free layer 21, a barrier layer 22, and a fixed layer 23, which are arranged in sequence along the direction from the surface of the spin-orbit torque providing line 1 to the side away from the spin-orbit torque providing line 1; that is, the free layer 21 of the magnetic tunnel junction 2 is arranged close to the spin-orbit torque providing line 1, and the fixed layer 23 is arranged away from the spin-orbit torque providing line 1. The specific structure of the magnetic tunnel junction 2 can refer to the prior art, and will not be repeated here.

[0039] The two obvious structural features of the SOT-MTJ device are: the SOT track layer provides an independent channel for the write current, and the read and write are separated; secondly, a horizontal magnetic field needs to be applied along the current direction to achieve the deterministic flipping of the vertical free layer 21, and the flipping polarity depends on the relative direction of the horizontal magnetic field acting on the free layer 21 and the current. Correspondingly, in this embodiment, the magnetic field direction of the free layer 21 and the fixed layer 23 in the magnetic tunnel junction 2 is a vertical direction, that is, in this embodiment, the magnetic tunnel junction 2 is specifically a vertically magnetized MTJ, and the reference layer of the magnetic tunnel junction 2 is vertically magnetized. In this embodiment, the direction parallel to the axis of the spin-orbit moment providing line 1 is determined as the first direction, and the direction of the magnetic field applied during initialization is determined as the initial magnetization direction. The initial magnetization direction will be perpendicular to the above-mentioned first direction, which can be perpendicular to the first direction in the horizontal plane or perpendicular to the first direction in the vertical plane.

[0040] In this embodiment, an auxiliary magnetic structure 3 is also provided, and the auxiliary magnetic structure 3 applies magnetic fields of different directions, i.e., bias magnetic fields, to the two magnetic tunnel junctions 2 in a differential bit. For each magnetic tunnel junction 2, the bias magnetic field it is subjected to needs to have a component along the first direction and a component along the initial magnetization direction. For a differential bit, the bias magnetic fields to which its two magnetic tunnel junctions 2 are subjected respectively need to have the same component direction along the initial magnetization direction and opposite component directions along the first direction. Normally, the components of the bias magnetic field to which the two magnetic tunnel junctions 2 in a differential bit are subjected along the first direction need to be substantially equal.

[0041] During the initialization process, after the magnetic storage unit is initialized by the external magnetic field along the initial magnetization direction, the auxiliary magnetic structure 3 applies the magnetic field along the first direction to the two magnetic tunnel junctions 2 in the same differential bit in opposite directions, so that the stray field directions of the free layer 21 in the magnetic tunnel junction 2 are opposite. When current passes through the spin-orbit moment providing line 1, the two free layers 21 will be written in opposite directions, thereby realizing the storage of differential information.

[0042] The specific contents of the auxiliary magnetic structure 3 will be described in detail in the following embodiments of the invention and will not be elaborated here.

[0043] In a magnetic storage unit provided by an embodiment of the present invention, the bias magnetic field provided by the auxiliary magnetic structure 3 to the magnetic tunnel junction 2 has components in both the first direction and the initial magnetization direction, and the components of the bias magnetic field along the first direction of the two magnetic tunnel junctions 2 in the same differential bit are opposite, and the components along the initial magnetization direction are the same. Therefore, only one initial magnetization along the initial magnetization direction is required to make the stray field of the bias magnetic field in the horizontal component direction of the free layer 21 of the two magnetic tunnel junctions 2 opposite, and complete the initialization, thereby simultaneously solving the reliable writing problem and high-speed reading problem of the perpendicularly magnetized MTJ zero magnetic field.

[0044] The specific structure of a magnetic storage unit provided by the present invention will be described in detail in the following invention embodiments.

[0045] Please refer to Figures 2 to 4 , Figure 2 A schematic structural diagram of a first specific magnetic storage unit provided by an embodiment of the present invention; Figure 3 for Figure 2 A schematic diagram of a top view structure; Figure 4 A schematic structural diagram of a second specific magnetic storage unit provided in an embodiment of the present invention.

[0046] Different from the above-mentioned invention embodiment, the present invention embodiment further defines the structure of the auxiliary magnetic structure 3 on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0047] See also Figure 2 as well as Figure 3 In the embodiment of the present invention, a separation layer 24 is provided on the surface of the magnetic tunnel junction 2 on the side facing away from the spin-orbit moment providing line 1; the auxiliary magnetic structure 3 includes an auxiliary magnetic layer 31 with an in-plane easy axis located on the surface of the separation layer 24 on the side facing away from the spin-orbit moment providing line 1; the magnetic moment of the auxiliary magnetic layer 31 has an angle with the first direction, so that the magnetic moments of the two auxiliary magnetic layers 31 corresponding to the same differential bit have opposite component directions along the first direction and the same component directions along the second direction; the second direction is a direction perpendicular to the first direction in a horizontal plane.

[0048] In this embodiment, a corresponding auxiliary magnetic layer 31 is provided on the top of each magnetic tunnel junction 2 facing away from the spin-orbit moment providing line 1, and the auxiliary magnetic layer 31 is used to provide a bias magnetic field to the corresponding magnetic tunnel junction 2. A separation layer 24 is provided between the auxiliary magnetic layer 31 and the magnetic tunnel junction 2. The separation layer 24 needs to be a conductive material to ensure electrical connection between the auxiliary magnetic layer 31 and the magnetic tunnel junction 2; at the same time, magnetic coupling between the auxiliary magnetic layer 31 and the magnetic tunnel junction 2 needs to be avoided. The specific material of the separation layer 24 can be set according to actual conditions, as long as the above functions can be achieved, and no specific limitation is made here.

[0049] In this embodiment, an auxiliary magnetic layer 31 is required to be arranged on the top of each magnetic tunnel junction 2, and the auxiliary magnetic layer 31 has a magnetic moment along the horizontal direction, and the auxiliary magnetic layer 31 has an in-plane easy axis. In this embodiment, the direction perpendicular to the first direction on the horizontal surface is the second direction. For each auxiliary magnetic layer 31, its magnetic moment has an angle with the first direction, and the angle makes the magnetic moment of the auxiliary magnetic layer 31 have a component corresponding to the first direction and a component corresponding to the second direction. In this embodiment, two auxiliary magnetic layers 31 are required to be arranged for a differential bit, and the directions of the components of the magnetic moments of the two auxiliary magnetic layers 31 corresponding to the first direction need to be opposite, that is, along the first direction, the magnetic moment direction of one auxiliary magnetic layer 31 is to the left, and the magnetic moment direction of the other auxiliary magnetic layer 31 is to the right. The components of the magnetic moments of the two auxiliary magnetic layers 31 corresponding to the second direction need to be the same. At this time, the second direction is the initial magnetization direction. After initial magnetization along the second direction, the two auxiliary magnetic layers 31 in the same differential bit can provide magnetic moments in opposite directions along the first direction, so that the stray fields received by the free layers 21 in the two magnetic tunnel junctions 2 in the same differential bit are in opposite directions. When current passes through the spin-orbit moment providing line 1, the two free layers 21 will be written in opposite directions, thereby realizing the storage of differential information.

[0050] In this embodiment, the auxiliary magnetic layer 31 is generally a ferromagnetic material, such as Co, Fe, CoFe or NiFe, etc. The auxiliary magnetic layer 31 can be elliptical or rectangular to have a magnetic moment in the above direction. Specifically, in this embodiment, the angles corresponding to the two auxiliary magnetic layers 31 corresponding to the same differential bit can be complementary angles, that is, the angle between the magnetic moment of one auxiliary magnetic layer 31 in the same differential bit and the first direction is 45°, and the angle between the magnetic moment of the other auxiliary magnetic layer 31 and the first direction is 135°. At this time, after initial magnetization, the two auxiliary magnetic layers 31 corresponding to the same differential bit can provide magnetic moment components of equal magnitude and opposite direction along the first direction. As a result, the stray fields generated by the auxiliary magnetic layer 31 on the two free layers 21 of the same differential bit are opposite in direction and equal in magnitude. When a current passes through the spin-orbit moment providing line 1, the two free layers 21 will be written in opposite directions.

[0051] In the embodiment of the present invention, the angle between the auxiliary magnetic layer 31 corresponding to the same differential bit and the first direction is in the range of 20° to 70°, including the end value; the angle between the other auxiliary magnetic layer 31 and the first direction is in the range of 110° to 160°, including the end value. When the angle is within the above range, the initialization of the differential bit can be completed by applying only one magnetic field.

[0052] See also Figure 4 Furthermore, in this embodiment, the auxiliary magnetic structure 3 may also include a pinning layer 32 located on the surface of the auxiliary magnetic layer 31 facing away from the spin-orbit torque providing line 1; the magnetic moment direction of the pinning layer 32 corresponds to the magnetic moment direction of the auxiliary magnetic layer 31 in contact with it.

[0053] That is, in this embodiment, each auxiliary magnetic layer 31 is coupled to a corresponding pinning layer 32, and the pinning layer 32 is usually arranged on the surface of the auxiliary magnetic layer 31 facing away from the spin-orbit moment providing line 1. Usually, each auxiliary magnetic layer 31 needs to be coupled to a corresponding pinning layer 32, and at this time, a differential bit is usually provided with two pinning layers 32. In this embodiment, the pinning layer 32 provides an exchange bias for the corresponding auxiliary magnetic layer 31, and the pinning layer 32 is usually made of antiferromagnetic materials, such as IrMn, PtMn and other materials.

[0054] During initialization, an external magnetic field along the second direction needs to be applied at a temperature higher than the Neel temperature of the pinned layer 32 and maintained for a period of time; after cooling, the external magnetic field is removed to establish an antiferromagnetic coupling between the pinned layer 32 and the corresponding auxiliary magnetic layer 31. After initialization, the orientation of the auxiliary magnetic layer 31 along the first direction is equal in magnitude and opposite in direction, and due to the pinned layer 32, it is not easily disturbed by the external magnetic field.

[0055] A magnetic storage unit provided by an embodiment of the present invention has an auxiliary magnetic structure 3 specifically located at the top of the corresponding magnetic tunnel junction 2, so that the unit only needs to be initially magnetized once along the second direction to make the stray field of the bias magnetic field in the opposite direction of the horizontal component of the free layer 21 of the two magnetic tunnel junctions 2, thereby completing initialization and accelerating the reading and writing speeds.

[0056] The specific structure of a magnetic storage unit provided by the present invention will be described in detail in the following invention embodiments.

[0057] Please refer to Figures 5 to 7 , Figure 5 A schematic structural diagram of a third specific magnetic storage unit provided by an embodiment of the present invention; Figure 6 A schematic structural diagram of a fourth specific magnetic storage unit provided by an embodiment of the present invention; Figure 7 for Figure 6 Schematic diagram of the side structure.

[0058] Different from the above-mentioned invention embodiment, the present invention embodiment further defines the structure of the auxiliary magnetic structure 3 on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0059] In the embodiment of the present invention, the auxiliary magnetic structure 3 includes an auxiliary magnetic body 33, and the auxiliary magnetic body 33 provides the bias magnetic field to the two magnetic tunnel junctions 2 in the same differential bit. That is, in this embodiment, the auxiliary magnetic structure 3 is specifically a whole auxiliary magnetic body 33, rather than a separate component arranged on the top of the magnetic tunnel junction 2 as in the aforementioned embodiment. In this embodiment, the above-mentioned bias magnetic field is provided to the two magnetic tunnel junctions 2 in a differential bit at the same time by an auxiliary magnetic body 33. In this embodiment, two specific methods are provided, both of which realize the above-mentioned function by an auxiliary magnetic body 33.

[0060] See also Figure 5 In the embodiment of the present invention, the auxiliary magnetic body 33 is located on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, and the auxiliary magnetic body 33 has perpendicular magnetic anisotropy. In this embodiment, a third direction in a vertical plane is determined, and the third direction is perpendicular to the spin-orbit moment providing line 1, that is, perpendicular to the above-mentioned first direction. In the present structure, the auxiliary magnetic body 33 is located on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, and the auxiliary magnetic body 33 needs to have perpendicular magnetic anisotropy, and it needs to have a high coercive force, and its typical value usually needs to be greater than 2kOe. The auxiliary magnetic body 33 needs to be magnetized in the vertical direction, that is, magnetized in the above-mentioned third direction. At this time, the auxiliary magnetic body 33 can apply magnetic moments opposite to the first direction to the two magnetic tunnel junctions 2 in the same differential bit.

[0061] The auxiliary magnetic body 33 may be in the shape of a cuboid or a cylinder, and its material may be CoPt, CoTb or CoGa, etc. In this way, the free layers 21 of the two magnetic tunnel junctions 2 in the same differential bit can sense the horizontal magnetic field in opposite directions, thereby realizing the above-mentioned differential bit function, that is, a single current writes the two magnetic tunnel junctions 2 into opposite states. In addition, through appropriate material optimization, the SAF (antiferromagnetic) stray field inside the magnetic tunnel junction 2 and the vertical direction (third direction) component of the stray field of the auxiliary magnetic body 33 on the free layer 21 can be offset, thereby avoiding the influence of the auxiliary magnetic body 33 on the magnetic tunnel junction 2 in the third direction.

[0062] Normally, the auxiliary magnetic body 33 is located in the middle of the two magnetic tunnel junctions 2 of the same differential bit, so that the free layers 21 of the two magnetic tunnel junctions 2 in the same differential bit feel a horizontal magnetic field of equal magnitude and opposite direction. Of course, the auxiliary magnetic body 33 may not be arranged on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, but may be arranged in a position parallel to the magnetic tunnel junction 2, or the magnetic tunnel junction 2 may be arranged on the side facing away from the spin-orbit moment providing line 1, as long as the above function can be achieved. Of course, depending on the position of the magnetic tunnel junction 2, its initial magnetization direction needs to be determined separately. When the auxiliary magnetic body 33 is located on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, and the auxiliary magnetic body 33 has perpendicular magnetic anisotropy, it is close to the free layer 21, which can fully affect the orientation of the free layer 21. At the same time, through appropriate material optimization, the influence of the auxiliary magnetic body 33 on the magnetic tunnel junction 2 in the third direction can be avoided.

[0063] See also Figure 6 as well as Figure 7 In an embodiment of the present invention, two groups of differential bits are included, the spin-orbit moment providing lines 1 of the two groups of differential bits are parallel, the auxiliary magnetic body 33 is located between the two groups of differential bits, and one auxiliary magnetic body 33 provides the bias magnetic field to the two groups of differential bits, a total of four magnetic tunnel junctions 2.

[0064] That is, in this embodiment, two groups of differential bits are firstly provided, and the two groups of differential bits are parallel to each other, that is, the spin-orbit moment providing lines 1 of the two groups of differential bits are parallel. The above-mentioned auxiliary magnetic body 33 is provided between the two groups of differential bits, and at this time, the auxiliary magnetic body 33 can provide the above-mentioned bias magnetic field to the two groups of differential bits, a total of four magnetic tunnel junctions 2.

[0065] The two sets of differential bits usually need to be arranged relative to each other, and the auxiliary magnetic body 33 needs to be located between the two sets of differential bits. Specifically, the auxiliary magnetic body 33 can be arranged on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, or can be arranged in parallel with the magnetic tunnel junction 2, or can be arranged on the side of the magnetic tunnel junction 2 facing away from the spin-orbit moment providing line 1, as long as the above functions can be achieved. Usually, the auxiliary magnetic body 33 is arranged on the side of the spin-orbit moment providing line 1 facing away from the magnetic tunnel junction 2, at a position close to the free layer 21.

[0066] In this structure, the auxiliary magnetic body 33 can be elliptical or rectangular, and the stray field generated by it can affect two sets of differential bits at the same time. The initial magnetization direction corresponding to the structure is the second direction, which is perpendicular to the first direction through which the write current passes. In this structure, the component of the stray field of the auxiliary magnetic body 33 in the third direction (perpendicular to both the first direction and the second direction) has little effect on the offset of the free layer 21 in the magnetic tunnel junction 2.

[0067] Typically, the auxiliary magnetic body 33 needs to be located in the middle of the two magnetic tunnel junctions 2 of the same differential bit to provide stray fields of equal magnitude and opposite direction along the first direction.

[0068] It should be noted that a top electrode is usually provided at the top of the magnetic storage unit provided in each embodiment of the application, that is, the side facing away from the spin-orbit moment providing line 1, for electrical connection with other structures.

[0069] A magnetic storage unit provided by an embodiment of the present invention has an auxiliary magnetic structure 3 which is specifically a separately arranged auxiliary magnetic body 33, which only needs to be subjected to an initial magnetization along the initial magnetization direction once, so that the stray field of the bias magnetic field can be made to have the opposite direction of the horizontal component of the free layer 21 of the two magnetic tunnel junctions 2, thereby completing the initialization and accelerating the reading and writing speeds.

[0070] The present application also provides a SOT-MRAM memory, which is provided with a magnetic storage unit disclosed in any of the above-mentioned embodiments of the invention. Generally, in this embodiment, the SOT-MRAM memory includes a plurality of the above-mentioned magnetic storage units distributed in an array. For other structures of the SOT-MRAM memory, reference can be made to the prior art, which will not be described in detail here.

[0071] Since the magnetic storage unit provided in the above-mentioned application embodiment can realize the writing of differential signals only through one initial magnetization, it can have a faster read and write speed. The corresponding SOT-MRAM memory provided in this embodiment can usually have a faster read and write speed, and the initialization process is simpler. The specific structure of the magnetic storage unit provided in this application has been described in detail in the above-mentioned invention embodiment, and will not be repeated here.

[0072] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0073] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0074] The above is a detailed introduction to a magnetic storage unit and a SOT-MRAM memory provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A magnetic storage unit, characterized in that: The invention comprises at least one set of differential bits and an auxiliary magnetic structure; the differential bits include: The spin-orbit moment provides the line; Two magnetic tunnel junctions located on one side of the spin-orbit moment providing line; the differential bit has a first direction parallel to the axis of the spin-orbit moment providing line, and an initial magnetization direction perpendicular to the first direction; The auxiliary magnetic structure provides a bias magnetic field to two magnetic tunnel junctions in the same differential bit, respectively. The bias magnetic field has a component along the first direction and a component along the initial magnetization direction. The components of the two bias magnetic fields along the initial magnetization direction are in the same direction, and the components of the two bias magnetic fields along the first direction are in opposite directions.

2. The magnetic storage unit according to claim 1, characterized in that A separation layer is provided on the surface of the magnetic tunnel junction facing away from the spin-orbit moment providing line; The auxiliary magnetic structure includes an auxiliary magnetic layer with an in-plane easy axis located on the surface of the separation layer facing away from the spin-orbit moment providing line; the magnetic moment of the auxiliary magnetic layer has an angle with the first direction, so that the components of the magnetic moments of the two auxiliary magnetic layers corresponding to the same differential bit are opposite in direction along the first direction and the components are the same in direction along the second direction; the second direction is a direction perpendicular to the first direction in a horizontal plane.

3. The magnetic storage unit according to claim 2, characterized in that The included angles of the two auxiliary magnetic layers corresponding to the same differential bit are complementary angles.

4. The magnetic storage unit according to claim 3, characterized in that The angle between the auxiliary magnetic layer corresponding to the same differential bit and the first direction ranges from 20° to 70°, including the endpoint values; the angle between the other auxiliary magnetic layer and the first direction ranges from 110° to 160°, including the endpoint values.

5. The magnetic storage unit according to claim 2, characterized in that The auxiliary magnetic structure further includes a pinning layer located on a surface of the auxiliary magnetic layer facing away from the spin-orbit moment providing line; the magnetic moment direction of the pinning layer corresponds to the magnetic moment direction of the auxiliary magnetic layer in contact with the pinning layer.

6. The magnetic storage unit according to claim 1, characterized in that The auxiliary magnetic structure includes an auxiliary magnetic body, and the auxiliary magnetic body provides the bias magnetic field to the two magnetic tunnel junctions in the same differential bit.

7. The magnetic storage unit according to claim 6, characterized in that The auxiliary magnetic body is located on a side of the spin-orbit moment providing line facing away from the magnetic tunnel junction, and the auxiliary magnetic body has perpendicular magnetic anisotropy.

8. The magnetic storage unit according to claim 6, characterized in that The auxiliary magnetic body is located in the middle of the two magnetic tunnel junctions of the same differential bit.

9. The magnetic storage unit according to claim 6, characterized in that It comprises two groups of differential bits, the spin-orbit moment providing lines of the two groups of differential bits are parallel, the auxiliary magnetic body is located between the two groups of differential bits, and one auxiliary magnetic body provides the bias magnetic field to the two groups of differential bits, a total of four magnetic tunnel junctions.

10. A SOT-MRAM memory, characterized in that: The SOT-MRAM memory comprises the magnetic storage unit according to any one of claims 1 to 9.

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