Magnetic tunnel junction, magnetic random access memory and read-write method thereof

Abstract

The invention relates to the field of magnetic storage, and discloses a magnetic tunnel junction, a magnetic random access memory and a read-write method thereof. The synthetic antiferromagnetic layer is arranged on the surface of the seed layer; the reference layer is arranged on the surface, deviating from the seed layer, of the synthetic antiferromagnetic layer; the barrier layer is arranged on the surface, deviating from the synthetic antiferromagnetic layer, of the reference layer; the free layer is arranged on the surface, deviating from the reference layer, of the barrier layer; the material of the free layer is a nonlinear antiferromagnetic material, and the free layer is provided with four steady-state resistors. The material of the free layer is a nonlinear antiferromagnetic material and has four steady-state resistors, the magnetic tunnel junction can be controlled to overturn among different steady states through a write current during write operation, and the resistance values in the four steady states are read through a TMR effect, so that a single magnetic tunnel junction can store 2-bit data, and the stability of the magnetic tunnel junction is improved. The magnetic tunnel junction is a two-end device, so that the storage density of a single magnetic tunnel junction is improved, and the problem that the domain wall staying position needs to be controlled in a three-end device is avoided.

Description

Technical Field

[0001] The present application relates to the field of magnetic storage, and in particular to a magnetic tunnel junction, a magnetic random access memory and a reading and writing method thereof. Background Art

[0002] Magnetic Random Access Memory (MRAM) is a non-volatile secondary memory. In order to improve the storage density / capacity of MRAM, it can be achieved through multi-bit storage.

[0003] At present, there are two ways to achieve multi-bit storage for magnetic random access memory. The first is to connect multiple magnetic tunnel junctions (MTJ) in series or in parallel; the second is to use domain wall (DW) propagation. Multiple magnetic tunnel junctions connected in series or in parallel do not strictly belong to a single magnetic tunnel junction to achieve multi-bit storage, and a magnetic tunnel junction can only store 1 bit of data; devices using domain wall propagation are three-terminal devices, in which the three terminals are located at the bottom, the two sides and the top respectively. In this method, the residence position of the domain wall is not easy to control.

[0004] Therefore, how to solve the above technical problems should be the focus of technical personnel in this field. Summary of the invention

[0005] The purpose of the present application is to provide a magnetic tunnel junction, a magnetic random access memory and a reading and writing method thereof, so as to improve the storage capacity of a single magnetic tunnel junction.

[0006] In order to solve the above technical problems, the present application provides a magnetic tunnel junction, comprising:

[0007] Seed layer;

[0008] A synthetic antiferromagnetic layer disposed on a surface of the seed layer;

[0009] A reference layer disposed on a surface of the synthetic antiferromagnetic layer away from the seed layer;

[0010] A barrier layer disposed on a surface of the reference layer facing away from the synthetic antiferromagnetic layer;

[0011] A free layer disposed on a surface of the barrier layer facing away from the reference layer;

[0012] The material of the free layer is a nonlinear antiferromagnetic material, and the free layer has four steady-state resistors.

[0013] Optionally, in the magnetic tunnel junction, the material of the reference layer is a nonlinear antiferromagnetic material.

[0014] Optionally, in the magnetic tunnel junction, the material of the reference layer is a magnetic material.

[0015] Optionally, in the magnetic tunnel junction, the free layer is a single-layer structure.

[0016] Optionally, in the magnetic tunnel junction, the free layer includes at least two stacked sub-free layers.

[0017] Optionally, in the magnetic tunnel junction, the nonlinear antiferromagnetic material includes one or more of Mn3Sn, Mn3Pt, and Mn3Ir.

[0018] Optionally, in the magnetic tunnel junction, the material of the reference layer includes one or more of CoFeB, CoFe, and Fe.

[0019] Optionally, in the magnetic tunnel junction, the material of the barrier layer includes one or more of MgO, MgAl2O4 or Al2O3.

[0020] The present application also provides a magnetic random access memory, comprising any one of the magnetic tunnel junctions described above.

[0021] The present application also provides a method for reading and writing the magnetic random access memory, comprising:

[0022] Write operation: applying a write voltage to the magnetic random access memory to generate a write current, wherein the write current flows through two ends of a magnetic tunnel junction in the magnetic random access memory to change the magnetic tunnel junction from a current steady-state resistance to another steady-state resistance; the magnetic tunnel junction has four steady-state resistances;

[0023] Read operation: applying a read voltage to the magnetic random access memory to generate a read current to read the data information stored in the magnetic random access memory.

[0024] A magnetic tunnel junction provided in the present application includes: a seed layer; a synthetic antiferromagnetic layer arranged on the surface of the seed layer; a reference layer arranged on the surface of the synthetic antiferromagnetic layer away from the seed layer; a barrier layer arranged on the surface of the reference layer away from the synthetic antiferromagnetic layer; and a free layer arranged on the surface of the barrier layer away from the reference layer; wherein the material of the free layer is a nonlinear antiferromagnetic material, and the free layer has four steady-state resistors.

[0025] It can be seen that the magnetic tunnel junction in the present application includes a seed layer, a synthetic antiferromagnetic layer, a reference layer, a barrier layer and a free layer, and the material of the free layer is a nonlinear antiferromagnetic material with four steady-state resistors. When performing a write operation, the magnetic tunnel junction can be controlled to flip between different stable states by writing current, and the resistance values ​​in four stable states can be read out by the TMR (tunneling magnetoresistance) effect to achieve a single magnetic tunnel junction that can store 2 bits of data, and the storage density is increased by 100%. In addition, the magnetic tunnel junction in the present application is a two-terminal device, which avoids the problem of needing to control the domain wall stop position in a three-terminal device while improving the storage density of a single magnetic tunnel junction.

[0026] In addition, the present application also provides a magnetic random access memory and a reading and writing method thereof having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a schematic diagram of the structure of a magnetic random access memory when a domain wall propagation method is adopted in the related art;

[0029] Figure 2 A schematic diagram of the structure of a magnetic tunnel junction provided in an embodiment of the present application;

[0030] Figure 3 The effect diagram of the magnetic tunnel junction in the embodiment of the present application and the magnetic tunnel junction in the related technology is shown;

[0031] In the figure, 1. seed layer, 2. synthetic antiferromagnetic layer, 3. reference layer, 4. barrier layer, 5. free layer, 6. cap layer. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the present application, the present application 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 application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] As described in the background technology section, in order to achieve multi-bit storage, multiple magnetic tunnel junctions can be connected in series or in parallel, but this method does not strictly belong to the single magnetic tunnel junction to achieve multi-bit storage; or domain wall propagation can be used, such as Figure 1 As shown, the device using domain wall propagation is a three-terminal device, in which the three terminals are located at the two sides of the bottom and the top respectively. In this method, the residence position of the domain wall is not easy to control.

[0035] In view of this, the present application provides a magnetic tunnel junction, please refer to Figure 2 ,include:

[0036] Seed layer 1;

[0037] A synthetic antiferromagnetic layer 2 is provided on the surface of the seed layer 1;

[0038] A reference layer 3 is provided on a surface of the synthetic antiferromagnetic layer 2 away from the seed layer 1;

[0039] A barrier layer 4 is provided on a surface of the reference layer 3 away from the synthetic antiferromagnetic layer 2;

[0040] A free layer 5 is provided on a surface of the barrier layer 4 away from the reference layer 3;

[0041] The material of the free layer 5 is a nonlinear antiferromagnetic material, and the free layer 5 has four steady-state resistors.

[0042] It should be pointed out that the magnetic tunnel junction in the present application may further include a capping layer 6 . The capping layer 6 is disposed on the surface of the free layer 5 away from the barrier layer 4 . The capping layer 6 has a protective function to prevent the magnetic tunnel junction from being oxidized.

[0043] The non-linear antiferromagnetic material is not specifically limited in the present application. For example, the non-linear antiferromagnetic material may include one or more of Mn3Sn, Mn3Pt, and Mn3Ir.

[0044] In this application, a nonlinear antiferromagnetic material is introduced into the free layer 5 (FL), and the antiferromagnetic Octupole spin is steadily flipped at 0, 60, 120 and 180 degrees by STT (spin transfer torque) or SOT (spin orbit torque) write current (Jc). Each steady state corresponds to a steady-state resistor. Four steady-state resistance values ​​are read out through the TMR effect to realize that a single magnetic tunnel junction can store 2 bits of data - "00", "01", "10", "11".

[0045] The magnetic tunnel junction in the related art has only two steady-state resistors and can only store 1 bit of data - "0" and "1". The magnetic tunnel junction in this application and the magnetic tunnel junction in the related art read and write control effect diagram are as follows Figure 3 shown.

[0046] As an implementation method, the free layer 5 is a single-layer structure layer. However, the present application does not specifically limit this. As another implementation method, the free layer 5 includes at least two stacked sub-free layers, wherein each sub-free layer is made of different materials, and the number of sub-free layers can be two, three, four, etc.

[0047] The synthetic antiferromagnetic (SAF) layer 2 may include a multi-layer stack formed of Co / Pt, or a multi-layer stack formed of Co / Ni.

[0048] The material of the barrier layer 4 includes one or more of MgO, MgAl2O4 or Al2O3.

[0049] As an implementation method, the material of the reference layer 3 is a nonlinear antiferromagnetic material, wherein the nonlinear antiferromagnetic material may include one or more of Mn3Sn, Mn3Pt, and Mn3Ir.

[0050] As another possible implementation mode, the material of the reference layer 3 is a magnetic material, and the magnetic material includes but is not limited to Fe, Co, CoB, CoFe, and CoFeB.

[0051] The reference layer 3 may be a single-layer structure layer, or the reference layer 3 includes at least two stacked sub-reference layers.

[0052] The magnetic tunnel junction in this embodiment includes a seed layer 1, a synthetic antiferromagnetic layer 2, a reference layer 3, a barrier layer 4 and a free layer 5, wherein the material of the free layer 5 is a nonlinear antiferromagnetic material having four steady-state resistors. When performing a write operation, the magnetic tunnel junction can be controlled to flip between different steady states by a write current, and the resistance values ​​in four steady states can be read out by the TMR (tunneling magnetoresistance) effect, so that a single magnetic tunnel junction can store 2 bits of data, and the storage density is increased by 100%. Moreover, the magnetic tunnel junction in this application is a two-terminal device, which avoids the problem of needing to control the domain wall stop position in a three-terminal device while increasing the storage density of a single magnetic tunnel junction.

[0053] The present application also provides a magnetic random access memory, which includes the magnetic tunnel junction described in the above embodiment.

[0054] The present application also provides a method for reading and writing the magnetic random access memory in the above embodiment, comprising:

[0055] Write operation: applying a write voltage to the magnetic random access memory to generate a write current, wherein the write current flows through two ends of a magnetic tunnel junction in the magnetic random access memory to change the magnetic tunnel junction from a current steady-state resistance to another steady-state resistance; the magnetic tunnel junction has four steady-state resistances;

[0056] Read operation: applying a read voltage to the magnetic random access memory to generate a read current to read the data information stored in the magnetic random access memory.

[0057] The writing method may be STT (spin transfer torque) or SOT (spin orbit torque).

[0058] 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.

[0059] The magnetic tunnel junction, magnetic random access memory and its reading and writing method provided by the present application are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation method of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A magnetic tunnel junction, characterized in that: include: Seed layer; A synthetic antiferromagnetic layer disposed on a surface of the seed layer; A reference layer disposed on a surface of the synthetic antiferromagnetic layer away from the seed layer; A barrier layer disposed on a surface of the reference layer facing away from the synthetic antiferromagnetic layer; A free layer disposed on a surface of the barrier layer facing away from the reference layer; The material of the free layer is a nonlinear antiferromagnetic material, and the free layer has four steady-state resistors.

2. The magnetic tunnel junction according to claim 1, wherein: The material of the reference layer is a nonlinear antiferromagnetic material.

3. The magnetic tunnel junction according to claim 1, wherein: The material of the reference layer is magnetic material.

4. The magnetic tunnel junction according to claim 1, wherein: The free layer is a single-layer structure layer.

5. The magnetic tunnel junction according to claim 1, wherein: The free layer includes at least two stacked sub-free layers.

6. The magnetic tunnel junction according to claim 1, wherein: The nonlinear antiferromagnetic material includes one or more of Mn3Sn, Mn3Pt, and Mn3Ir.

7. The magnetic tunnel junction according to claim 3, characterized in that: The material of the reference layer includes one or more of CoFeB, CoFe, and Fe.

8. The magnetic tunnel junction according to claim 1, wherein: The material of the barrier layer includes one or more of MgO, MgAl2O4 or Al2O3.

9. A magnetic random access memory, characterized in that: Comprising the magnetic tunnel junction as claimed in any one of claims 1 to 8.

10. The method for reading and writing a magnetic random access memory as claimed in claim 9, characterized in that: include: Write operation: applying a write voltage to the magnetic random access memory to generate a write current, wherein the write current flows through two ends of a magnetic tunnel junction in the magnetic random access memory to change the magnetic tunnel junction from a current steady-state resistance to another steady-state resistance; the magnetic tunnel junction has four steady-state resistances; Read operation: applying a read voltage to the magnetic random access memory to generate a read current to read the data information stored in the magnetic random access memory.

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