Magnetic tunnel junctions immune to magnetic interference

Abstract

The application provides a magnetic tunnel junction with magnetic interference resistance, comprising: a magnetic tunnel junction, which comprises a pinning layer, a barrier layer and a free layer which are sequentially stacked; a spacer layer, which is arranged on the surface of the free layer away from the barrier layer; and a soft magnetic layer, which is arranged on the surface of the spacer layer away from the free layer, and the magnetization direction of the soft magnetic layer changes synchronously with the direction of an external magnetic field, so that the soft magnetic layer generates a stray field with an opposite direction to the external magnetic field and acts on the free layer. The magnetic tunnel junction with magnetic interference resistance provided by the application can offset the influence of the external magnetic field on the free layer through the stray field generated by the soft magnetic layer, and improve the magnetic interference resistance of the magnetic tunnel junction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic storage, in particular to a magnetic tunnel junction with anti-magnetic interference. BACKGROUND

[0002] The MRAM chip with magnetic tunnel junction as a basic unit is extremely sensitive to external magnetic field interference. Especially for the vertical MRAM chip, the dynamic anti-magnetic ability of the horizontal magnetic field perpendicular to the direction of the free layer magnetic moment is poor, even much weaker than the vertical magnetic field. Therefore, the horizontal magnetic field can significantly increase the write error rate. Therefore, it is necessary to improve the anti-magnetic ability of the tunnel junction horizontal magnetic field from the device level in order to improve the anti-magnetic reliability short board. However, for the prior art, using magnetic shielding or setting anti-magnetic structure is easy to lead to complex structure of the magnetic tunnel junction or decrease of storage density. SUMMARY

[0003] The magnetic tunnel junction with anti-magnetic interference provided by the present application can offset the influence of the external magnetic field on the free layer through the stray field generated by the soft magnetic layer, and improve the anti-magnetic interference ability of the magnetic tunnel junction.

[0004] The present application provides a magnetic tunnel junction with anti-magnetic interference, comprising:

[0005] The magnetic tunnel junction comprises a pinning layer, a barrier layer and a free layer which are sequentially stacked;

[0006] The spacer layer is arranged on the surface of the free layer away from the barrier layer;

[0007] The soft magnetic layer is arranged on the surface of the spacer layer away from the free layer, and the magnetization direction of the soft magnetic layer changes synchronously with the direction of the external magnetic field, so that the soft magnetic layer generates a stray field with opposite direction to the external magnetic field and acts on the free layer.

[0008] Optionally, the spacer layer is formed by combining one or more of non-magnetic metal, non-magnetic insulator and anti-ferromagnetic material.

[0009] Optionally, the soft magnetic layer is formed by using a material with positive correlation characteristics between magnetization curve and external magnetic field intensity.

[0010] Optionally, the soft magnetic layer is formed by using a material with coercive force lower than 1mT and magnetic anisotropy field of 50-500mT.

[0011] Optionally, the soft magnetic layer comprises a single layer film layer formed by using any one of the materials with high magnetic permeability and high spin polarization rate, or the soft magnetic layer comprises a composite film layer formed by using the materials with high magnetic permeability and high spin polarization rate; wherein,

[0012] The high magnetic permeability material comprises one or a combination of soft magnetic material, anti-ferromagnetic material, ferrimagnetic material, artificial anti-ferromagnetic material.

[0013] The high spin polarization rate material comprises one or a combination of Fe, CoFeB and CoFe.

[0014] Optionally, the thickness of the soft magnetic layer is 0.5-10 nm, and the thickness of the spacer layer is 0.5-3 nm.

[0015] Optionally, the soft magnetic layer exhibits a demagnetization state, a perpendicular magnetization state or an oblique magnetization state under an external magnetic field with a strength of 0.

[0016] Optionally, the soft magnetic layer is formed of a soft magnetic metal material exhibiting a demagnetization state under an external magnetic field with a strength of 0, the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal, and the soft magnetic layer generates an in-plane polarized spin transfer torque when a write current is applied under an external magnetic field in the in-plane direction.

[0017] Optionally, the soft magnetic layer is formed of a weakly perpendicular magnetic anisotropy material exhibiting a perpendicular magnetization under an external magnetic field with a strength of 0, the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal, and the soft magnetic layer generates a spin transfer torque with an out-of-plane polarization component and an in-plane polarization component when a write current is applied under an external magnetic field in the in-plane direction.

[0018] Optionally, the soft magnetic layer comprises a composite film layer formed by coupling a first film layer formed of a high spin polarization rate material and a second film layer formed of a high magnetic permeability material, and the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal; wherein,

[0019] The first film layer and the second film layer exhibit a demagnetization state under an external magnetic field with a strength of 0, and the composite film layer generates an in-plane polarized spin transfer torque when a write current is applied under an external magnetic field in the in-plane direction.

[0020] In the technical solution provided in the application, the spacer layer and the soft magnetic layer are arranged on the free layer of the magnetic tunnel junction, the magnetization direction of the soft magnetic layer changes with the external magnetic field, so that, when the external magnetic field exists, the soft magnetic layer forms the same magnetization direction as the external magnetic field, and then, due to the characteristic of magnetic field line closure, a stray field in the opposite direction is generated outside the soft magnetic layer, the stray field is opposite to the direction of the external magnetic field, and the stray field offsets part of the external magnetic field, thereby reducing the influence of the external magnetic field on the free layer and effectively reducing the read / write error rate. Meanwhile, the soft magnetic layer is magnetized, and when a write current is applied, a spin transfer torque parallel to the magnetization direction is generated, thereby effectively reducing the flipping time and improving the write efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1Schematic diagram of a magnetic tunnel junction with magnetic interference resistance according to an embodiment of the present invention;

[0022] Figure 2 Magnetization response characteristic of a soft magnetic layer of a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention;

[0023] Figure 3 Principle diagram of a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention under zero field;

[0024] Figure 4 Principle diagram of a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention under an external magnetic field;

[0025] Figure 5 Magnetization curve of a soft magnetic layer formed by a soft magnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention;

[0026] Figure 6 Magnetization curve of a soft magnetic layer formed by a ferrimagnetic material or an antiferromagnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention;

[0027] Figure 7 Magnetization curve of a soft magnetic layer formed by an artificial antiferromagnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention;

[0028] Figure 8 State diagram of a spacer layer formed by a soft magnetic layer formed by a soft magnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention in combination with a non-magnetic insulator material under zero field;

[0029] Figure 9 State diagram of a spacer layer formed by a soft magnetic layer formed by a soft magnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention in combination with a non-magnetic metal material under an external magnetic field;

[0030] Figure 10 State diagram of a spacer layer formed by a soft magnetic layer formed by a soft magnetic material in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention in combination with a non-magnetic metal material under an external magnetic field;

[0031] Figure 11 State diagram of a soft magnetic layer formed by a material with weak perpendicular magnetic anisotropy in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention under zero field;

[0032] Figure 12 State diagram of a soft magnetic layer formed by a material with weak perpendicular magnetic anisotropy in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention under an external magnetic field;

[0033] Figure 13 State diagram of a soft magnetic layer including a composite film layer in a magnetic tunnel junction with magnetic interference resistance according to another embodiment of the present invention under zero field;

[0034] Figure 14 Figure 8 is a state diagram of a soft magnetic layer including a composite film layer in a magnetic tunnel junction against magnetic interference under an external magnetic field according to another embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] The embodiments of the present application provide a magnetic tunnel junction against magnetic interference, as shown in Figure 1 , comprising:

[0037] a magnetic tunnel junction, the magnetic tunnel junction comprising a pinned layer, a barrier layer, and a free layer which are sequentially stacked;

[0038] a spacer layer, the spacer layer being arranged on a surface of the free layer away from the barrier layer;

[0039] a soft magnetic layer, the soft magnetic layer being arranged on a surface of the spacer layer away from the free layer, a magnetization direction of the soft magnetic layer synchronously changing with a direction of an external magnetic field, so that the soft magnetic layer generates a stray field having an opposite direction to the external magnetic field and acts on the free layer.

[0040] In some embodiments, the soft magnetic layer generates a sensitive response under an applied external magnetic field, and generates significant magnetization parallel to the direction of the magnetic field, and a magnetization curve is as shown in Figure 2 , which is a linear positive correlation characteristic under a horizontal magnetic field, for example, an x-direction magnetic field, and a saturation magnetic field is Hk, also known as an anisotropy field, Hk is preferably 50 mT-500 mT. As shown in Figure 3 , an exemplary soft magnetic layer formed of a material exhibiting a demagnetization state under an external magnetic field with a strength of 0 is shown, the soft magnetic layer is applied with a write current when there is no external magnetic field interference, and only a spin transfer torque is provided by the pinned layer, and continues as shown in Figure 4 , when an in-plane magnetic field, for example, an x-direction external magnetic field, is applied, the soft magnetic layer is magnetized, and a stray layer opposite to the direction of the magnetic field is generated at the position of the free layer, which offsets part of the external magnetic field and reduces the interference of the external magnetic field. At the same time, the soft magnetic layer also generates a horizontal spin transfer torque acting on the free layer when the write current is applied, which improves the flipping efficiency.

[0041] In the technical solution provided in this embodiment of the invention, a spacer layer and a soft magnetic layer are disposed on the free layer of the magnetic tunnel junction. The magnetization direction of the soft magnetic layer changes with the external magnetic field. Thus, when an external magnetic field is present, the soft magnetic layer forms a magnetization direction with the same as the external magnetic field. Furthermore, due to the closed nature of magnetic field lines, a stray field in the opposite direction is generated outside the soft magnetic layer. The stray field is opposite to the direction of the external magnetic field, which cancels out part of the external magnetic field, reducing the influence of the external magnetic field on the free layer and effectively reducing the read / write error rate. At the same time, the soft magnetic layer is magnetized, and when a write current is applied, a spin-transfer torque parallel to the magnetization direction is generated, thereby effectively reducing the flip-flop time and improving the write efficiency.

[0042] As an alternative implementation, the spacer layer is formed using one or more of the following: non-magnetic metals, non-magnetic insulators, and antiferromagnetic materials.

[0043] As an alternative implementation, the soft magnetic layer is formed using a material whose magnetization curve is positively correlated with the external magnetic field strength.

[0044] In some embodiments, materials whose magnetization curves are positively correlated with the external magnetic field strength typically include soft magnetic materials, antiferromagnetic and subferromagnetic materials, or artificial antiferromagnetic materials. For example, such as Figure 5 As shown, the magnetization curve of a soft magnetic material is illustrated. The horizontal axis represents the external magnetic field strength, and the vertical axis represents the magnetization of the soft magnetic material. Figure 5 It is known that soft magnetic materials will spontaneously demagnetize when the external magnetic field strength is 0, and will exhibit magnetization that is linearly positively correlated with the external magnetic field strength when the external magnetic field strength is not 0. For example, ... Figure 6 As shown, the magnetization curves of antiferromagnetic and ferrimagnetic materials are illustrated. The horizontal axis represents the external magnetic field strength, and the vertical axis represents the magnetization intensity of the antiferromagnetic or ferrimagnetic material. Figure 6 It is known that antiferromagnetic or subferromagnetic materials exhibit antiferromagnetic properties or weak magnetism under zero field conditions; when the external magnetic field strength is not zero, they exhibit magnetization that is linearly positively correlated with the external magnetic field. For example, such as... Figure 7 As shown, the magnetization curves of an artificial antiferromagnetic material with weak vertical anisotropy are illustrated. The horizontal axis represents the external magnetic field strength, and the vertical axis represents the magnetization of the artificial antiferromagnetic material. Based on... Figure 7 It is known that artificial antiferromagnetic materials exhibit ferromagnetism locally and antiferromagnetism or weak magnetism overall. Furthermore, when the external magnetic field strength is not zero, they exhibit magnetization intensity that is linearly positively correlated with the external magnetic field.

[0045] As an optional implementation, the soft magnetic layer is formed of a material with a coercivity of less than 1 mT and a magnetic anisotropy field of 50 to 500 mT.

[0046] As an optional embodiment, the soft magnetic layer comprises a single layer film formed by any one of high permeability material and high spin polarization rate material, or the soft magnetic layer comprises a composite film layer formed by high permeability material and high spin polarization rate material; wherein,

[0047] The high permeability material comprises one or a combination of soft magnetic material, anti-ferromagnetic material, ferrimagnetic material, artificial anti-ferromagnetic material;

[0048] The high spin polarization rate material comprises one or a combination of Fe, CoFeB, CoFe.

[0049] As an optional embodiment, the thickness of the soft magnetic layer is 0.5nm-10nm, and the thickness of the spacer layer is 0.5nm-3nm.

[0050] As an optional embodiment, the soft magnetic layer exhibits demagnetization state, perpendicular magnetization state or oblique magnetization state under the external magnetic field with intensity of 0.

[0051] As an optional embodiment, the soft magnetic layer is formed by soft magnetic metal material exhibiting demagnetization state under the external magnetic field with intensity of 0, the spacer layer is formed by non-magnetic insulator or non-magnetic metal, and the soft magnetic layer generates in-plane polarized spin transfer torque when a write current is applied under the in-plane external magnetic field.

[0052] In some embodiments, as shown in Figure 8 and Figure 9 , an exemplary structure is provided, in which the soft magnetic layer is formed by soft magnetic metal material exhibiting demagnetization state under the external magnetic field with intensity of 0, and the spacer layer is formed by non-magnetic insulator, Figure 8 The state of the structure is shown when the intensity of the external magnetic field is 0, in which the soft magnetic layer is spontaneously demagnetized, and the spin transfer torque is not generated to the free layer when a write current is applied, and the free layer is only affected by the spin transfer torque of the pinning layer. Figure 9 Figure 8 When the in-plane external magnetic field is applied, the state of the structure is shown, in which the soft magnetic layer is magnetized in the in-plane direction due to the magnetic field when a write current is applied, the soft magnetic layer generates in-plane polarized spin transfer torque to increase the flipping efficiency of the free layer, and a stray field is generated in the opposite direction of the magnetization direction of the external magnetic field to resist the influence of the in-plane external magnetic field. Figure 10 As shown in Figure 8 and Figure 9 , an exemplary structure is provided, in which the soft magnetic layer is formed by soft magnetic metal material exhibiting demagnetization state under the external magnetic field with intensity of 0, and the spacer layer is formed by non-magnetic metal, i.e., the structure is equivalent to the structure in which the spacer layer in Figure 8 and Figure 9 is replaced by non-magnetic metal.Figure 10 The structure in the figure can have the same effect as Figure 8 and Figure 9 The resistivity of the non-magnetic metal is lower than that of the non-magnetic insulator, and the non-magnetic metal has less influence on the giant magnetoresistance effect of the magnetic tunnel junction.

[0053] As an optional embodiment, the soft magnetic layer is formed of a material with weak perpendicular magnetic anisotropy and perpendicular magnetization under an external magnetic field with a strength of 0, and the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal. When a write current is applied to the soft magnetic layer under an external magnetic field in the in-plane direction, the soft magnetic layer generates a spin transfer torque with an out-of-plane polarization component and an in-plane polarization component.

[0054] In some embodiments, as shown in Figure 11 and Figure 12 , an exemplary structure is provided, in which the soft magnetic layer is formed of a material with weak perpendicular magnetic anisotropy and perpendicular magnetization under an external magnetic field with a strength of 0, and the spacer layer can be formed of one or more of a non-magnetic metal, a non-magnetic insulator, or an anti-ferromagnetic material. In Figure 11 , the state under an external magnetic field with a strength of 0 is shown, in which the soft magnetic layer is in a perpendicular magnetization state and can generate a spin transfer torque with a perpendicular polarization. As shown in Figure 12 , when an in-plane magnetic field is applied, the soft magnetic layer tilts, and the magnetization direction follows the magnetic field direction. When a write current is applied, a spin transfer torque in the tilting direction is generated, i.e., a spin transfer torque with both an out-of-plane polarization component and an in-plane polarization component.

[0055] As an optional embodiment, the soft magnetic layer includes a first film layer formed of a material with high spin polarization rate and a second film layer formed of a material with high magnetic permeability, and the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal. In this embodiment,

[0056] The first film layer and the second film layer are in a demagnetized state under an external magnetic field with a strength of 0, and the composite film layer generates an in-plane polarization spin transfer torque when a write current is applied under an external magnetic field in the in-plane direction.

[0057] In some embodiments, as shown in Figure 13 and Figure 14 , an exemplary structure is provided, in which the soft magnetic layer includes a first film layer formed of a material with high spin polarization rate and a second film layer formed of a material with high magnetic permeability, and the spacer layer can be formed of one or more of a non-magnetic metal, a non-magnetic insulator, or an anti-ferromagnetic material. The first film layer is a material with high spin polarization rate, which can efficiently generate a spin transfer torque, and the second film layer is a material with high magnetic permeability, which exhibits super-soft magnetic characteristics and is easily magnetized by a magnetic field. The two layers are strongly coupled. As shown in Figure 13As shown, when the external magnetic field strength is 0, both are demagnetized due to coupling, so the first film layer does not generate spin transfer torque. Figure 14 As shown, a write current is applied under the action of in-plane magnetic field, the second film layer is magnetized due to the magnetic field, and the first film layer is also in-plane magnetized under the action of interlayer coupling, so the in-plane polarized spin transfer torque can be generated.

[0058] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any change or replacement that can be easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An application of a magnetic tunnel junction with anti-magnetic interference capability in reducing the influence of external magnetic fields on the free layer, characterized in that, include: A magnetic tunnel junction, comprising a pinned layer, a barrier layer, and a free layer stacked sequentially. A spacer layer is disposed on the surface of the free layer opposite to the barrier layer; A soft magnetic layer is disposed on the surface of the spacer layer opposite to the free layer. The magnetization direction of the soft magnetic layer changes synchronously with the direction of the external magnetic field, so that the soft magnetic layer generates a stray field with the opposite direction to the external magnetic field and acts on the free layer. The soft magnetic layer is magnetized, and when a write current is applied, the soft magnetic layer also generates a spin-transfer torque parallel to the magnetization direction, which acts on the free layer to reduce the flip-flop time. The soft magnetic layer is formed using a material whose magnetization curve is positively correlated with the external magnetic field strength; the material whose magnetization curve is positively correlated with the external magnetic field strength includes soft magnetic materials, antiferromagnetic materials, subferromagnetic materials, or artificial antiferromagnetic materials.

2. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The spacer layer is formed by a combination of one or more of the following: non-magnetic metals, non-magnetic insulators, and antiferromagnetic materials.

3. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer is formed of a material with a coercivity of less than 1 mT and a magnetic anisotropy field of 50 to 500 mT.

4. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer comprises a monolayer film formed using either a material with high magnetic permeability or a material with high spin polarization; or, the soft magnetic layer comprises a composite film formed using a material with high magnetic permeability and a material with high spin polarization. The high magnetic permeability material includes one or a combination of soft magnetic materials, antiferromagnetic materials, subferromagnetic materials, and artificial antiferromagnetic materials; The high spin polarizability material includes one or more combinations of Fe, CoFeB, and CoFe.

5. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The thickness of the soft magnetic layer is 0.5nm~10nm, and the thickness of the spacer layer is 0.5nm~3nm.

6. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer exhibits a demagnetized state, a vertically magnetized state, or an inclined magnetized state under an external magnetic field of strength of 0.

7. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer is formed of a soft magnetic metal material that exhibits a demagnetized state under an external magnetic field of strength 0. The spacer layer is formed of a non-magnetic insulator or a non-magnetic metal. When a write current is applied to the soft magnetic layer under an external magnetic field in the in-plane direction, it generates an in-plane polarized spin-transfer torque.

8. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer is formed of a weakly perpendicular magnetic anisotropic material that exhibits perpendicular magnetization under an external magnetic field of strength 0. The spacer layer is formed of a non-magnetic insulator or a non-magnetic metal. When a write current is applied to the soft magnetic layer under an external magnetic field in the in-plane direction, a spin-transfer torque with out-of-plane polarization components and in-plane polarization components is generated.

9. The application of the magnetic tunnel junction with anti-magnetic interference as described in claim 1 in reducing the influence of external magnetic fields on the free layer, characterized in that, The soft magnetic layer comprises a composite film formed by coupling a first film layer made of a high spin polarizability material and a second film layer made of a high magnetic permeability material, wherein the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal; wherein... The first and second films are demagnetized under an external magnetic field of zero strength. When a write current is applied to the composite film under an external magnetic field in the in-plane direction, it generates an in-plane polarized spin-transfer torque.

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