Magnetic tunnel junction resistant to magnetic interference

Abstract

The invention provides an anti-magnetic interference magnetic tunnel junction comprising a magnetic tunnel junction which comprises a pinning layer, a barrier layer and a free layer which are stacked in sequence; the spacer layer is arranged on the surface, deviating from the barrier layer, of the free layer; the soft magnetic layer is arranged on the surface, away from the free layer, of the spacing layer, and the magnetization direction of the soft magnetic layer and the direction of an external magnetic field synchronously change, so that the soft magnetic layer generates a stray field in the direction opposite to that of the external magnetic field and acts on the free layer. According to the anti-magnetic-interference magnetic tunnel junction provided by the invention, the influence of an external magnetic field on the free layer can be counteracted through a stray field generated by the soft magnetic layer, and the anti-magnetic-interference capability of the magnetic tunnel junction is improved.

Description

Technical Field

[0001] The present invention relates to the field of magnetic storage technology, and in particular to a magnetic tunnel junction resistant to magnetic interference. Background Art

[0002] The magnetic storage MRAM chip, which uses the magnetic tunnel junction as the basic unit, is extremely sensitive to interference from the external magnetic field. Especially for vertical MRAM chips, their dynamic anti-magnetic ability is poor for magnetic fields perpendicular to the direction of the free layer magnetic moment, that is, horizontal magnetic fields, and is even much weaker than vertical magnetic fields. Therefore, horizontal magnetic fields will significantly increase the write error rate. Therefore, it is necessary to improve the anti-magnetic ability of the tunnel junction in the horizontal magnetic field at the device level in order to improve its anti-magnetic reliability shortcomings. However, for existing technologies, the use of magnetic shielding or the setting of anti-magnetic structures can easily lead to complex structures of magnetic tunnel junctions or reduced storage density. Summary of the Invention

[0003] The magnetic tunnel junction with anti-magnetic interference provided by the present invention can offset the influence of the external magnetic field on the free layer through the stray field generated by the soft magnetic layer, thereby improving the anti-magnetic interference capability of the magnetic tunnel junction.

[0004] The present invention provides a magnetic tunnel junction resistant to magnetic interference, comprising: A magnetic tunnel junction, comprising a pinned layer, a barrier layer, and a free layer stacked in sequence; a spacer layer, the spacer layer being arranged on a surface of the free layer facing away from the barrier layer; A soft magnetic layer is provided on a 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 a direction opposite to the external magnetic field and acts on the free layer.

[0005] Optionally, the spacer layer is formed by a combination of one or more of non-magnetic metal, non-magnetic insulator and anti-ferromagnetic material.

[0006] Optionally, the soft magnetic layer is formed of a material whose magnetization curve has a positive correlation with the external magnetic field intensity.

[0007] Optionally, the soft magnetic layer is formed of a material with a coercive force lower than 1 mT and a magnetic anisotropy field of 50-500 mT.

[0008] Optionally, the soft magnetic layer comprises a single film layer formed of any one of a material with high magnetic permeability and a material with high spin polarization rate, or the soft magnetic layer comprises a composite film layer formed of a material with high magnetic permeability and a material with high spin polarization rate; wherein, The high magnetic permeability material includes one or a combination of soft magnetic materials, antiferromagnetic materials, ferrimagnetic materials, and artificial antiferromagnetic materials; The high spin polarization material includes one or more of Fe, CoFeB, and CoFe.

[0009] Optionally, the thickness of the soft magnetic layer is 0.5 nm to 10 nm, and the thickness of the spacer layer is 0.5 nm to 3 nm.

[0010] Optionally, the soft magnetic layer exhibits a demagnetized state, a perpendicular magnetized state, or an inclined magnetized state under an external magnetic field with an intensity of 0.

[0011] Optionally, the soft magnetic layer is formed of a soft magnetic metal material that exhibits a demagnetized state under an external magnetic field with an intensity 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, an in-plane polarized spin transfer torque is generated.

[0012] Optionally, the soft magnetic layer is formed of a weak perpendicular magnetic anisotropy material that exhibits perpendicular magnetization under an external magnetic field of intensity 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, a spin transfer torque having an out-of-plane polarization component and an in-plane polarization component is generated.

[0013] Optionally, the soft magnetic layer comprises a composite film layer formed by coupling 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; wherein, The first film layer and the second film layer are in a demagnetized state under an external magnetic field with an intensity of 0. When a write current is applied to the composite film layer under an external magnetic field in an in-plane direction, an in-plane polarized spin transfer torque is generated.

[0014] In the technical solution provided by the present invention, a spacer layer and a 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. Therefore, when an external magnetic field is present, the soft magnetic layer forms a magnetization direction identical to that of the external magnetic field. In addition, due to the closed nature of the magnetic flux 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, partially offsetting the external magnetic field, reducing the impact of the external magnetic field on the free layer and effectively reducing the read and 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, effectively reducing the switching time and improving the write efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a magnetic tunnel junction resistant to magnetic interference according to an embodiment of the present invention; Figure 2 The magnetization response characteristics of the soft magnetic layer of the magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention; Figure 3A schematic diagram of a magnetic tunnel junction with magnetic interference immunity under zero field according to another embodiment of the present invention; Figure 4 This is a schematic diagram of a magnetic tunnel junction resistant to magnetic interference under an external magnetic field according to another embodiment of the present invention; Figure 5 A magnetization curve of a soft magnetic layer formed of a soft magnetic material in a magnetic tunnel junction that is resistant to magnetic interference according to another embodiment of the present invention; Figure 6 A magnetization curve of a soft magnetic layer formed of a ferrimagnetic material or an antiferromagnetic material in a magnetic tunnel junction for resisting magnetic interference according to another embodiment of the present invention; Figure 7 A magnetization curve of a soft magnetic layer formed of an artificial antiferromagnetic material in a magnetic tunnel junction resistant to magnetic interference according to another embodiment of the present invention; Figure 8 This is a state diagram of a soft magnetic layer formed of a soft magnetic material and a spacer layer formed of a non-magnetic insulating material in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under zero field; Figure 9 This is a diagram showing the state of a soft magnetic layer formed of a soft magnetic material and a spacer layer formed of a non-magnetic insulating material in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under an external magnetic field; Figure 10 This is a diagram showing the state of a soft magnetic layer formed of a soft magnetic material and a spacer layer formed of a non-magnetic metal material in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under an external magnetic field; Figure 11 This is a state diagram of a soft magnetic layer formed of a material with weak perpendicular magnetic anisotropy in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under zero field; Figure 12 This is a diagram showing the state of a soft magnetic layer formed of a material with weak perpendicular magnetic anisotropy in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under an external magnetic field; Figure 13 A state diagram of a soft magnetic layer including a composite film layer in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under zero field; Figure 14 This is a state diagram of a soft magnetic layer including a composite film layer in a magnetic tunnel junction with anti-magnetic interference according to another embodiment of the present invention under an external magnetic field. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 efforts shall fall within the scope of protection of the present invention.

[0017] The embodiment of the present invention provides a magnetic tunnel junction that is resistant to magnetic interference, such as Figure 1 Shown, including: A magnetic tunnel junction, comprising a pinned layer, a barrier layer, and a free layer stacked in sequence; a spacer layer, the spacer layer being arranged on a surface of the free layer facing away from the barrier layer; A soft magnetic layer is provided on a 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 a direction opposite to the external magnetic field and acts on the free layer.

[0018] In some embodiments, the soft magnetic layer responds sensitively to an external magnetic field and undergoes significant magnetization parallel to the magnetic field direction. The magnetization curve is as follows: Figure 2 As shown, in a horizontal magnetic field, for example, in the x-direction magnetic field, it is a linear positive correlation characteristic, and the saturation magnetic field is Hk, also known as the anisotropic field, and Hk is preferably 50mT~500mT. Figure 3 As shown in FIG, a soft magnetic layer is formed of a material that is in a demagnetized state under an external magnetic field with an intensity of 0. When a write current is applied to the soft magnetic layer without external magnetic field interference, only the pinned layer provides spin transfer torque. Figure 4 As shown, when an in-plane magnetic field is applied, such as an external magnetic field in the X direction, the soft magnetic layer is magnetized, and a stray layer in the opposite 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, when a write current is applied to the soft magnetic layer, a horizontal spin transfer torque is generated to act on the free layer, thereby improving the flipping efficiency.

[0019] In the technical solution provided by the embodiments of the present invention, a spacer layer and a soft magnetic layer are provided on the free layer of the magnetic tunnel junction. The magnetization direction of the soft magnetic layer changes with the external magnetic field. Therefore, when an external magnetic field is present, the soft magnetic layer forms a magnetization direction identical to that of the external magnetic field. Furthermore, due to the closed nature of the magnetic flux lines, a stray field in the opposite direction is generated outside the soft magnetic layer. The stray field is in the opposite direction to the external magnetic field, partially offsetting the external magnetic field, reducing the impact of the external magnetic field on the free layer and effectively reducing the read and 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 switching time and improving the write efficiency.

[0020] As an optional implementation manner, the spacer layer is formed by a combination of one or more of non-magnetic metal, non-magnetic insulator and anti-ferromagnetic material.

[0021] As an optional implementation, the soft magnetic layer is formed of a material whose magnetization curve has a positive correlation with the external magnetic field intensity.

[0022] In some embodiments, the material having a positive correlation between the magnetization curve and the external magnetic field strength generally includes soft magnetic materials, antiferromagnetic and ferrimagnetic materials, or artificial antiferromagnetic materials. Figure 5 As shown, the magnetization curve of the soft magnetic material is shown. The horizontal axis is the external magnetic field strength, and the vertical axis is the magnetization strength of the soft magnetic material. Figure 5 It can be seen that soft magnetic materials will spontaneously demagnetize when the external magnetic field strength is 0, and will show a magnetization intensity that is linearly positively correlated with the external magnetic field when the external magnetic field strength is not 0. Figure 6 As shown, the magnetization curves of antiferromagnetic and ferrimagnetic materials are shown. The horizontal axis in the figure is the external magnetic field intensity, and the vertical axis is the magnetization intensity of the antiferromagnetic or ferrimagnetic material. Figure 6 It can be seen that antiferromagnetic or ferrimagnetic materials exhibit antiferromagnetic properties or weak magnetism under zero field; when the external magnetic field strength is not 0, they will show a magnetization intensity that is linearly positively correlated with the external magnetic field. For example, Figure 7 As shown, the magnetization curve of the artificial antiferromagnetic material with weak perpendicular anisotropy is shown. The horizontal axis in the figure is the external magnetic field intensity, and the vertical axis is the magnetization intensity of the artificial antiferromagnetic material. Figure 7 It can be seen that artificial antiferromagnetic materials exhibit ferromagnetism locally and antiferromagnetism or weak magnetism as a whole. Moreover, when the external magnetic field strength is not 0, the magnetization intensity will be linearly positively correlated with the external magnetic field.

[0023] As an optional implementation manner, the soft magnetic layer is formed of a material with a coercive force lower than 1 mT and a magnetic anisotropy field of 50-500 mT.

[0024] As an optional embodiment, the soft magnetic layer includes a single film layer formed by using any one of a material with high magnetic permeability and a material with high spin polarization rate, or the soft magnetic layer includes a composite film layer formed by using a material with high magnetic permeability and a material with high spin polarization rate; wherein, The high magnetic permeability material includes one or a combination of soft magnetic materials, antiferromagnetic materials, ferrimagnetic materials, and artificial antiferromagnetic materials; The high spin polarization material includes one or more of Fe, CoFeB, and CoFe.

[0025] As an optional implementation manner, the thickness of the soft magnetic layer is 0.5 nm to 10 nm, and the thickness of the spacer layer is 0.5 nm to 3 nm.

[0026] As an optional implementation, the soft magnetic layer exhibits a demagnetized state, a perpendicular magnetized state, or an inclined magnetized state under an external magnetic field with an intensity of 0.

[0027] As an optional embodiment, the soft magnetic layer is formed of a soft magnetic metal material that exhibits a demagnetized state under an external magnetic field with an intensity 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, an in-plane polarized spin transfer torque is generated.

[0028] In some embodiments, as Figure 8 and Figure 9 As shown, an exemplary embodiment provides a structure in which the soft magnetic layer is formed of a soft magnetic metal material that is in a demagnetized state under an external magnetic field with an intensity of 0, and the spacer layer is formed of a non-magnetic insulator. Figure 8 The figure shows the state of the structure when the external magnetic field strength is 0. In this state, the soft magnetic layer is spontaneously demagnetized. When a write current is applied, no spin transfer torque is generated in the free layer. The free layer is only affected by the spin transfer torque of the pinned layer. Figure 9 for Figure 8 The state of the structure when an external magnetic field is applied in the plane. When a write current is applied in this state, the soft magnetic layer is magnetized in the plane due to the magnetic field. The soft magnetic layer generates a spin transfer torque of the in-plane polarization, which increases the switching efficiency of the free layer. At the same time, it also generates a stray field with the opposite magnetization direction to the external magnetic field, thereby resisting the influence of the external magnetic field in the plane. Figure 10 As shown, an exemplary embodiment is provided in which the soft magnetic layer is formed of a soft magnetic metal material that is in a demagnetized state under an external magnetic field with an intensity of 0, and the spacer layer is formed of a non-magnetic metal. That is, the structure is equivalent to Figure 8 and Figure 9 The spacer layer in the magnetic field is replaced by a non-magnetic metal. Figure 10 The structure in can have Figure 8 and Figure 9 The same effect is achieved. At the same time, since the non-magnetic insulator is replaced by a non-magnetic metal, its resistivity is lower and the influence on the giant magnetoresistance effect of the magnetic tunnel junction is smaller.

[0029] As an optional embodiment, the soft magnetic layer is formed of a weak perpendicular magnetic anisotropy material that exhibits perpendicular magnetization under an external magnetic field of intensity 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, a spin transfer torque having an out-of-plane polarization component and an in-plane polarization component is generated.

[0030] In some embodiments, as Figure 11 and Figure 12 As shown, an exemplary structure is provided in which the soft magnetic layer is formed of a weak perpendicular magnetic anisotropy material that exhibits perpendicular magnetization under an external magnetic field of zero intensity, and the spacer layer can be formed of one or more of non-magnetic metals, non-magnetic insulators or antiferromagnets. Figure 11In the figure, the state when the external magnetic field strength is 0 is shown. The soft magnetic layer is perpendicularly magnetized, which can produce a perpendicular polarized spin transfer torque. Figure 12 As shown, when an in-plane magnetic field is applied, the soft magnetic layer tilts and the magnetization direction is along the direction of the magnetic field. When a write current is applied, a spin transfer torque in the tilted direction is generated, that is, a spin transfer torque with both out-of-plane polarization components and in-plane polarization components.

[0031] As an optional embodiment, the soft magnetic layer includes a composite film layer formed by coupling a first film layer formed of a material with a high spin polarization rate and a second film layer formed of a material with a high magnetic permeability, and the spacer layer is formed of a non-magnetic insulator or a non-magnetic metal; wherein, The first film layer and the second film layer are in a demagnetized state under an external magnetic field with an intensity of 0. When a write current is applied to the composite film layer under an external magnetic field in an in-plane direction, an in-plane polarized spin transfer torque is generated.

[0032] In some embodiments, as Figure 13 and Figure 14 As shown, a composite film layer is formed by coupling a first film layer formed of a high spin polarization material and a second film layer formed of a high magnetic permeability material. The spacer layer can be formed of one or more of non-magnetic metals, non-magnetic insulators or antiferromagnets. The first film layer is a high spin polarization material that can efficiently generate spin transfer torque; the second film layer is a high magnetic permeability material that exhibits super-soft magnetic properties and is easily magnetized by a magnetic field. There is a strong interlayer coupling between the two. Figure 13 As shown in , when the external magnetic field strength is 0, due to the coupling effect, both are in the demagnetized state, so the first film layer does not generate spin transfer torque. Figure 14 As shown, when a write current is applied under the action of an in-plane magnetic field, the second film layer is magnetized due to the magnetic field, and under the action of interlayer coupling, the first film layer is also magnetized in the plane, which can generate in-plane polarized spin transfer torque.

[0033] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A magnetic tunnel junction resistant to magnetic interference, characterized in that: include: A magnetic tunnel junction, comprising a pinned layer, a barrier layer, and a free layer stacked in sequence; a spacer layer, the spacer layer being arranged on a surface of the free layer facing away from the barrier layer; A soft magnetic layer is provided on a 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 a direction opposite to the external magnetic field and acts on the free layer.

2. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The spacer layer is formed by a combination of one or more of non-magnetic metal, non-magnetic insulator and anti-ferromagnetic material.

3. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer is formed of a material whose magnetization curve has a positive correlation with the external magnetic field intensity.

4. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer is formed of a material with a coercive force lower than 1 mT and a magnetic anisotropy field of 50-500 mT.

5. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer comprises a single film layer formed of any one of a material with high magnetic permeability and a material with high spin polarization rate, or the soft magnetic layer comprises a composite film layer formed of a material with high magnetic permeability and a material with high spin polarization rate; wherein, The high magnetic permeability material includes one or a combination of soft magnetic materials, antiferromagnetic materials, ferrimagnetic materials, and artificial antiferromagnetic materials; The high spin polarization material includes one or more of Fe, CoFeB, and CoFe.

6. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The thickness of the soft magnetic layer is 0.5 nm to 10 nm, and the thickness of the spacer layer is 0.5 nm to 3 nm.

7. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer is in a demagnetized state, a perpendicular magnetized state or an inclined magnetized state under an external magnetic field with an intensity of zero.

8. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer is formed of a soft magnetic metal material that is in a demagnetized state under an external magnetic field with an intensity of 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 an in-plane direction, an in-plane polarized spin transfer torque is generated.

9. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer is formed of a weak perpendicular magnetic anisotropy material that exhibits perpendicular magnetization under an external magnetic field with an intensity 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, a spin transfer torque having an out-of-plane polarization component and an in-plane polarization component is generated.

10. The magnetic tunnel junction resistant to magnetic interference according to claim 1, characterized in that: The soft magnetic layer comprises a composite film layer formed by coupling 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; wherein, The first film layer and the second film layer are in a demagnetized state under an external magnetic field with an intensity of 0. When a write current is applied to the composite film layer under an external magnetic field in an in-plane direction, an in-plane polarized spin transfer torque is generated.

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