JP2019121782A - Spin orbit torque type magnetization rotation element, spin orbit torque type magnetoresistance effect element, and manufacturing method of spin orbit torque type magnetization rotation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spin orbit torque type magnetization rotation element capable of causing magnetization rotation without applying an external magnetic field without increasing a current flowing through a spin orbit torque wiring layer. SOLUTION: This spin-orbit torque type magnetizing rotating element includes a spin-orbit torque wiring layer extending in the X direction and a first ferromagnetic layer laminated on the spin-orbit torque wiring layer, and has a first ferromagnetic layer. The layer has shape anisotropy, has a long axis in the X direction, and in a plane on which the spin-orbit torque wiring layer extends, the easy axis of magnetism of the first ferromagnetic layer is with respect to the X direction and the X direction. It is inclined with respect to the Y direction orthogonal to each other. [Selection diagram] Fig. 1

Description

  The present invention relates to a spin orbit torque type magnetization rotation element, a spin orbit torque type magnetoresistive effect element, and a method of manufacturing a spin orbit torque type magnetization rotation element.

  In a tunnel magnetoresistive (TMR) element using an insulating layer (tunnel barrier layer, barrier layer) in a nonmagnetic layer, a method of writing (magnetization rotation) using a magnetic field generated by a current or a lamination direction of magnetoresistive elements There is known a method of writing (magnetization rotation) using spin transfer torque (STT) generated by flowing a current through the The magnetization rotation of the TMR element using STT is efficient from the viewpoint of energy efficiency, but the current may be applied in the stacking direction of the magnetoresistive element to cause the magnetization rotation, which may deteriorate the TMR element. There is.

  In recent years, therefore, attention has been focused on spin orbit torque type magnetization rotating elements utilizing pure spin current generated by spin orbit interaction as a means for enabling magnetization rotation without flowing current in the stacking direction of the magnetoresistance effect element. There is. When current flows in the spin orbit torque wiring layer, a pure spin current is generated due to spin orbit interaction and the Rashba effect at the interface of different materials. The pure spin current induces a spin orbit torque (SOT), which causes magnetization rotation of the ferromagnetic material disposed on the spin orbit torque wiring by the SOT. Pure spin current is produced by the same number of upward spin electrons and downward spin electrons flowing in opposite directions, and the charge flow is offset. Therefore, the rotational current flowing through the magnetoresistive element is zero, and it is expected to extend the life of the magnetoresistive element. The spin orbit torque type magnetization rotation element can easily perform magnetization rotation as the current density flowing through the spin orbit torque wiring is higher.

  The spin orbit torque type magnetization rotation element is classified into several types according to the relationship between the direction of the current flowing through the spin orbit torque wiring and the direction of the easy axis of magnetization of the ferromagnetic material. The spin orbit torque type magnetization rotation element includes a spin orbit torque wiring layer extending in the X direction, and a first ferromagnetic layer laminated on one surface thereof. It is classified into an X-type, a Y-type and a Z-type magnetization rotation element according to the direction of the magnetization easy axis of the first ferromagnetic layer. The X-type magnetization rotation element has a magnetization easy axis in the same X direction as the spin orbit torque wiring layer. The Y type magnetization rotation element has an easy magnetization axis in the Y direction orthogonal to the X direction in the in-plane direction. The Z-type magnetization rotation element has an easy magnetization axis in the Z direction (stacking direction) orthogonal to the in-plane direction. The X-type and Z-type magnetization rotation elements have a short time required for magnetization rotation and can operate at high speed. Further, in the X-type magnetization rotation element, since the spin orbit torque wiring layer has the X direction as the major axis, the width in the Y direction can be narrowed. Therefore, the X-type magnetization rotation element can perform magnetization reversal with less current than the Y-type magnetization rotation element. However, X-type and Z-type magnetization rotating elements must apply an external magnetic field in the Z direction and X direction to the elements, respectively, in order to assist the magnetization rotation. Therefore, the X-type and Z-type magnetization rotation elements have problems in terms of energy consumption and integration. On the other hand, in the case of a Y-type magnetization rotation element, although the external magnetic field for assisting the magnetization rotation is unnecessary, the time required for the magnetization rotation is long, and the width in the Y direction is wide, so the current required for the magnetization switching is large. There is a drawback of that.

  In order to solve this problem, there has been proposed an XY-type magnetization rotation element in which the magnetization easy axis of the first ferromagnetic layer is inclined to either the X direction or the Y direction (for example, Non-Patent Document 1) . Such an XY type magnetization rotation element 501 is shown in FIG. The XY type magnetization rotation element 501 includes a spin orbit torque wiring layer 502, a first ferromagnetic layer 504, and an electrode 506. The first ferromagnetic layer 504 and the electrode 506 are stacked on one surface of the spin track torque wiring layer 502, and the electrode 506 sandwiches the first ferromagnetic layer 504 in plan view. Further, the first ferromagnetic layer 504 has a major axis inclined with respect to the X direction and the Y direction in plan view, unlike the spin track torque wiring layer 502 having the major axis in the X direction. The magnetization easy axis 508 of the first ferromagnetic layer 504 is oriented in a direction parallel to the long axis of the first ferromagnetic layer 504 due to shape anisotropy.

  Since the easy axis of magnetization of the XY-type magnetization rotation element 501 configured in this way has a Y-direction component, magnetization rotation occurs even if an external magnetic field is not applied. Further, since the magnetization easy axis has an X direction component, the time required for the magnetization rotation is short as compared with the Y-type magnetization rotation element, which is suitable for high speed operation.

S. Fukami, et al., Nature Nanotechnology, DOI: 10.1038 / NNANO.2016.29 Supplement

  However, since the major axis of the first ferromagnetic layer is inclined with respect to the X direction and the Y direction in the XY-type magnetization rotating element as shown in FIG. 11, the width of the spin orbit torque wiring layer in the Y direction is large. Become. Therefore, the current density flowing through the spin orbit torque wiring layer is reduced, and the current required for the magnetization rotation is increased.

  The present invention has been made in view of the above problems, and a spin track torque type magnetization rotating device capable of causing magnetization rotation without applying an external magnetic field without increasing the current flowing through the spin track torque wiring layer It is an object of the present invention to provide a method of manufacturing a spin orbit torque type magnetoresistive effect element and a spin orbit torque type magnetization rotation element.

  The present inventors incline only the magnetization easy axis of the first ferromagnetic layer from the long axis of the spin orbit torque wiring layer while aligning the long axis of the first ferromagnetic layer with the long axis of the spin orbit torque wiring layer. Accordingly, it has been found that the magnetization can be easily rotated without applying an external magnetic field without reducing the width of the spin orbit torque wiring layer and increasing the current flowing in the spin orbit torque wiring layer. That is, the present invention provides the following means in order to solve the above problems.

(1) The spin orbit torque type magnetization rotation device according to the first aspect includes a spin orbit torque wiring layer extending in the X direction, and a first ferromagnetic layer stacked on the spin orbit torque wiring layer. The first ferromagnetic layer has shape anisotropy, has a major axis in the X direction, and in the plane where the spin track torque wiring layer extends, the easy axis of magnetization of the first ferromagnetic layer is the X direction and X It is inclined with respect to the Y direction orthogonal to the direction.

(2) In the spin orbit torque type magnetization rotation device according to the above aspect, the first ferromagnetic layer may be a HoCo alloy SmFe alloy, an FePt alloy, a CoPt alloy or a CoCrPt alloy.

(3) The spin orbit torque type magnetoresistive effect element according to the second aspect is provided on the opposite side to the spin orbit torque wiring layer of the first ferromagnetic layer and the spin orbit torque type magnetization rotation element according to the above aspect And a second ferromagnetic layer whose magnetization direction is fixed, and a nonmagnetic layer disposed between the first ferromagnetic layer and the second ferromagnetic layer.

(4) The spin orbit torque type magnetoresistance effect device according to the above aspect may further include a third ferromagnetic layer disposed between the first ferromagnetic layer and the nonmagnetic layer.

(5) In the spin orbit torque type magnetoresistance effect device according to the above aspect, the first ferromagnetic layer may include the diffusion prevention layer on the surface of the first ferromagnetic layer on the nonmagnetic layer side.

(6) In the spin orbit torque type magnetoresistive effect element according to the above aspect, the diffusion prevention layer may contain nonmagnetic heavy metal.

(7) In the spin orbit torque type magnetoresistive element according to the above aspect, the diffusion prevention layer may have a thickness equal to or less than twice the ion radius of the element constituting the diffusion prevention layer.

(8) A method of manufacturing a spin orbiting torque type magnetization rotating device according to a third aspect is a method of manufacturing a spin orbiting torque type magnetization rotating element according to the above aspect, wherein at least the first ferromagnetic layer is Y The film is formed in the state where the magnetic field is applied in the direction including the direction.

(9) The manufacturing method according to the above aspect may include the step of performing annealing in a state in which a magnetic field is applied in a direction including the Y direction after film formation of at least the first ferromagnetic layer.

(10) A method of manufacturing a spin orbiting torque type magnetization rotating device according to a fourth aspect is a method of manufacturing a spin orbiting torque type magnetization rotating element according to the above aspect, wherein at least a first ferromagnetic layer is deposited. Thereafter, annealing is performed in a state in which the magnetic field is applied in the direction including the Y direction.

  According to the spin orbit torque type magnetization rotation element according to the above aspect, it is possible to cause magnetization rotation without applying an external magnetic field without increasing the current flowing through the spin orbit torque wiring layer.

FIG. 1 is a perspective view schematically showing a spin orbiting torque type magnetization rotating element according to an embodiment of the present invention. It is the top view which showed typically the spin orbit torque type magnetization rotation element which concerns on FIG. FIG. 7 is a plan view schematically showing a method of manufacturing a spin orbiting torque type magnetization rotating element according to an embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing a spin track torque type magnetoresistive effect element according to an embodiment of the present invention. FIG. 5 is a plan view schematically showing a spin orbit torque type magnetoresistive effect element according to FIG. 4; FIG. 5 is a plan view schematically showing a state in which the magnetization is inverted in the spin orbit torque type magnetoresistive effect element according to FIG. 4; FIG. 1 is a cross-sectional view schematically showing a spin track torque type magnetoresistive effect element according to an embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing a spin track torque type magnetoresistive effect element according to an embodiment of the present invention. FIG. 9 is a plan view schematically showing a spin orbit torque type magnetoresistive effect element according to FIG. 8; It is a top view of the magnetic recording array concerning 4th Embodiment. It is the top view which showed the conventional spin orbit torque type magnetization rotation element typically. It is the perspective view which showed typically another example of a spin track torque type magnetization rotation element.

  Hereinafter, the present invention will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show enlarged features for convenience for the purpose of clarifying the features of the present invention, and the dimensional ratio of each component may be different from the actual one. is there. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to them, and can be appropriately modified and implemented within the scope of achieving the effects of the present invention.

(Spin orbit torque type magnetization rotating element)
FIG. 1 is a perspective view schematically showing a spin orbiting torque type magnetization rotating element 1 according to an aspect of the present invention. FIG. 2 is a plan view schematically showing the spin orbiting torque type magnetization rotating element 1 according to FIG. A spin orbiting torque type magnetization rotating device 1 according to an aspect of the present invention includes a spin orbiting torque wiring layer 2, a first ferromagnetic layer 4 stacked on the spin orbiting torque wiring layer 2, and a first strong layer. And an electrode 6 stacked on the spin track torque wiring layer 2 with the magnetic layer 4 interposed therebetween. Hereinafter, the direction in which the long axis of spin track torque wiring layer 2 extends is the X direction, and the direction orthogonal to the X direction in the plane where spin track torque wiring layer 2 extends is the Y direction, X direction or Y direction. Also, let the direction orthogonal to be the Z direction. In FIG. 1, the stacking direction of the first ferromagnetic layer 4 is the Z direction. The first ferromagnetic layer 4 has shape anisotropy in which the major axis extends in the X direction. Further, the first ferromagnetic layer 4 has the magnetization 8 along the easy axis of magnetization which is inclined with respect to the X direction and the Y direction.

<Spin orbit torque wiring>
The spin orbit torque wiring layer 2 extends in the X direction. The spin orbit torque wiring layer 2 is connected to one surface of the first ferromagnetic layer 4 in the Z direction. The spin orbit torque wiring layer 2 may be directly connected to the first ferromagnetic layer 4 or may be connected via another layer.

  It is preferable that a layer interposed between the spin orbit torque wiring layer 2 and the first ferromagnetic layer 4 does not dissipate the spins propagating from the spin orbit torque wiring layer 2. For example, it is known that silver, copper, magnesium, aluminum, and the like have a long spin diffusion length of 100 nm or more and do not easily dissipate spin.

  The thickness of this layer is preferably equal to or less than the spin diffusion length of the material constituting the layer. If the thickness of the layer is equal to or less than the spin diffusion length, the spins propagating from the spin orbit torque wiring layer 2 can be sufficiently transmitted to the first ferromagnetic layer 4.

  The spin orbit torque wiring layer 2 is made of a material in which spin current is generated by the spin Hall effect when current flows. As such a material, a material having a configuration in which a spin current is generated in the spin orbit torque wiring layer 2 is sufficient. Therefore, it is not limited to a material composed of a single element, and may be composed of a part composed of a material in which a spin current is generated and a part composed of a material in which a spin current is not generated.

  The phenomenon that spin current is induced by the fact that the first spin S1 and the second spin S2 are bent in the opposite direction in the direction perpendicular to the direction of the current due to the spin-orbit interaction when a current flows through the material, Call it the Hall effect. The ordinary Hall effect and the spin Hall effect are common in that moving (moving) charges (electrons) can bend the direction of movement (moving), but the ordinary Hall effect causes charged particles moving in a magnetic field to move the Lorentz force. In contrast to being able to receive and bend the direction of movement, the spin Hall effect is largely different in that the direction of movement is bent only by electron movement (only current flow) even though there is no magnetic field.

  Since the number of electrons in the first spin S1 is equal to the number of electrons in the second spin S2 in a nonmagnetic material (a non-ferromagnetic material), the first ferromagnetic layer 8 of the spin orbit torque wiring layer 2 is arranged in the figure. The number of electrons of the first spin S1 going to the direction of the provided plane and the number of electrons of the second spin S2 going to the opposite direction to the electrons of the first spin S1 are equal. Thus, the current as a net flow of charge is zero. A spin current without this current is particularly called a pure spin current.

Here, the electron flow in the first spin S1 J _↑, electrons flow J _↓ second spin S2, to represent the spin current and _{J S,} is defined by _J S = _{J ↑} -J _↓. In FIG. 1, J _S flows upward in the figure as a pure spin current. Here, J _S is a flow of electrons having a polarizability of 100%.

  The spin orbit torque wiring layer 2 may contain nonmagnetic heavy metal. Here, heavy metal is used in the meaning of the metal which has specific gravity more than yttrium. The spin orbit torque wiring layer 2 may be made of only nonmagnetic heavy metal.

  In this case, the nonmagnetic heavy metal is preferably a nonmagnetic metal having an atomic number of 39 or more having d electrons or f electrons in the outermost shell. Such nonmagnetic metals have a large spin-orbit interaction that causes the spin Hall effect. The spin orbit torque wiring 2 may be made of only a nonmagnetic metal having a large atomic number of 39 or more having d electrons or f electrons in the outermost shell.

Normally, when current flows in metal, all electrons move in the direction opposite to the current regardless of the direction of spin, while nonmagnetic metal with large atomic number having d electrons or f electrons in the outermost shell Since the spin-orbit interaction is large, the direction of electron movement depends on the direction of electron spins by the spin Hall effect, and a pure spin current J _S tends to be generated.

  In addition, the spin track torque wiring layer 2 may contain a magnetic metal. Magnetic metal refers to ferromagnetic metal or antiferromagnetic metal. When the nonmagnetic metal contains a trace amount of magnetic metal, the spin-orbit interaction is enhanced, and the spin current generation efficiency with respect to the current flowing through the spin-orbit torque wiring layer 2 can be increased. The spin orbit torque wiring layer 2 may be made of only an antiferromagnetic metal.

  Since the spin-orbit interaction is caused by the intrinsic internal field of the material of the spin-orbit torque wiring material, a pure spin current is also generated in the nonmagnetic material. When a small amount of magnetic metal is added to the spin orbit torque wiring material, the spin current generation efficiency is improved because the magnetic metal itself scatters the electron spins flowing therethrough. However, if the amount of magnetic metal added is excessively increased, the generated spin current is scattered by the added magnetic metal, and as a result, the effect of decreasing the spin current becomes strong. Therefore, it is preferable that the molar ratio of the magnetic metal to be added be sufficiently smaller than the molar ratio of the main component of the spin generating portion in the spin track torque wiring. As a rule, the molar ratio of the magnetic metal added is preferably 3% or less.

  In addition, the spin track torque wiring layer 2 may include a topological insulator. The spin track torque wiring layer 2 may be made of only the topological insulator. The topological insulator is a substance in which the inside of the substance is an insulator or a high resistance, but a spin-polarized metal state is generated on the surface thereof. There is something like an internal magnetic field called spin-orbit interaction in matter. Therefore, even if there is no external magnetic field, a new topological phase appears due to the effect of spin-orbit interaction. This is a topological insulator, and strong spin-orbit interaction and inversion symmetry breaking at the edge can generate pure spin current with high efficiency.

The topological insulators _{example, SnTe, Bi 1.5 Sb 0.5 Te} 1.7 Se 1.3, TlBiSe 2, Bi 2 Te 3, Bi 1-x Sb x, (Bi 1-x Sb x) 2 Te _{3 and the} like are preferred. These topological insulators can generate spin current with high efficiency.

<First ferromagnetic layer>
The first ferromagnetic layer 4 is stacked on the spin track torque wiring layer 2 in the Z direction orthogonal to the X direction. The first ferromagnetic layer 4 has shape anisotropy in which the major axis extends in the X direction. Further, the first ferromagnetic layer 4 has the magnetization 8 having the easy magnetization axis in the direction inclined with respect to the X direction and the Y direction in the plane in which the spin track torque wiring layer 2 extends. The first ferromagnetic layer 4 preferably contains, for example, a HoCo alloy, a SmFe alloy, a FePt alloy, a CoPt alloy, or a CoCrPt alloy. The material of the first ferromagnetic layer 4 is preferably a tetragonal magnetic material having a c-axis length shorter than the a-axis length. If the c-axis length is shorter than the a-axis length, the magnetization easy axis of the first ferromagnetic layer 4 is likely to be oriented in the in-plane direction. For example, SmFe alloy (SmFe ₁₂₎ or the like are preferable. Also, if the c-axis length is longer than the a-axis length, the magnetization easy axis of the first ferromagnetic layer 4 is likely to be oriented in the perpendicular direction, but c is formed by film formation in a magnetic field or annealing in a magnetic field The axis can be oriented in the in-plane magnetic field direction. For example, Ho-Co alloy (HoCo ₂ ) or the like is preferable. These alloys have strong crystal magnetic anisotropy and a large damping constant, so that magnetization rotation hardly occurs. Therefore, the first ferromagnetic layer 4 formed using these materials has strong data retention.

  The major axis direction of the first ferromagnetic layer 4 is different from the direction of the magnetization easy axis of the first ferromagnetic layer 4. In this case, the direction of the magnetization easy axis of the magnetization 114 of the first ferromagnetic layer 4 can be determined, for example, by the following method.

  In the first method, a plurality of first ferromagnetic layers 4 manufactured under the same conditions are provided, and the magnetic characteristics thereof are measured. The magnetic properties can be performed using a vibrating sample magnetometer (VSM), a superconducting quantum interferometer (SQUID), a physical property measuring apparatus (PPMS), or the like.

  First, a plurality of first ferromagnetic layers 4 whose major axes are aligned in one direction are arranged, for example, in an array. Then, a constant magnetic field is applied to the element assembly of the first ferromagnetic layer 4 from a predetermined direction (reference direction) in the xy plane, and the magnetization of the first ferromagnetic layer 4 in the predetermined direction is measured. A plurality of first ferromagnetic layers 4 gather, and the element assembly exhibits measurable magnetization. This operation is measured at a plurality of points around the in-plane direction of the element assembly while changing the angle at which the magnetic field is applied.

  The magnetization characteristics of the element assembly can be obtained by plotting the magnitude of the magnetization in a predetermined direction as the ordinate and the inclination angle of the magnetic field applied to the element assembly from the reference direction as the abscissa. In the case where the first ferromagnetic layer 4 has an isotropic shape in the xy plane (for example, a circular shape in plan view), the measured magnetization characteristic has a sine curve. In addition, when the first ferromagnetic layer 4 has a major axis in one direction, and the direction of the magnetization easy axis of the first ferromagnetic layer 4 coincides with the major axis direction of the first ferromagnetic layer 4, the cosine curve The shape (tilt angle at each point of the graph) changes, but the tilt angle indicating the maximum magnetization matches the case of the isotropic shape. On the other hand, if the first ferromagnetic layer 4 has a major axis in one direction and the direction of the magnetization easy axis of the first ferromagnetic layer 4 is different from the major axis direction of the first ferromagnetic layer 4, the cosine As the shape of the curve (the inclination angle at each point of the graph) changes, the inclination angle indicating the maximum magnetization shifts. That is, when the inclination angle with respect to the reference direction at the position where the magnetization shows a peak in the graph is different from the inclination angle with respect to the reference direction with respect to the long axis direction of the first ferromagnetic layer 4, the long axis of the first ferromagnetic layer 4 It can be seen that the direction is different from the direction of the magnetization easy axis of the first ferromagnetic layer 4.

  The second method is a method of measuring the resistance value of the spin orbit torque type magnetization rotation element 1 while applying it to the spin orbit torque type magnetization rotation element 1. The resistance value of the spin orbit torque type magnetization rotation element 1 is measured while changing the angle at which a constant magnetic field is applied from a predetermined direction (reference direction) in the xy plane. The resistance value of the spin orbit torque type magnetization rotation element 1 is a resistance value between the upper surface of the first ferromagnetic layer 4 and one end of the spin orbit torque wiring layer 2, and mainly the resistance of the first ferromagnetic layer 4 It is a value.

  When plotting the resistance value of the spin orbit torque type magnetization rotation element 1 as the ordinate and the inclination angle of the magnetic field applied to the first ferromagnetic layer 4 from the reference direction as the abscissa, the resistance characteristic of the spin orbit torque type magnetization rotation element 1 is plotted. Is required. The resistance characteristic exhibits the same behavior as the above-mentioned magnetization characteristic. In the case where the first ferromagnetic layer 4 has an isotropic shape in the xy plane (for example, a circular shape in plan view), the resistance characteristic to be measured draws a cosine curve. In addition, when the first ferromagnetic layer 4 has a major axis in one direction, and the direction of the magnetization easy axis of the first ferromagnetic layer 4 coincides with the major axis direction of the first ferromagnetic layer 4, the cosine curve The shape (tilt angle at each point of the graph) changes, but the tilt angle showing the maximum resistance matches the case of the isotropic shape. On the other hand, if the first ferromagnetic layer 4 has a major axis in one direction and the direction of the magnetization easy axis of the first ferromagnetic layer 4 is different from the major axis direction of the first ferromagnetic layer 4, the cosine As the shape of the curve (the inclination angle at each point of the graph) changes, the inclination angle indicating the maximum magnetization shifts. That is, when the inclination angle with respect to the reference direction at the position where the resistance value shows a peak in the graph is different from the inclination angle with respect to the reference direction of the long axis direction of the first ferromagnetic layer 4, the length of the first ferromagnetic layer 4 It can be seen that the axial direction is different from the direction of the magnetization easy axis of the first ferromagnetic layer 4.

<Principle of spin orbit torque type magnetization rotating element>
Next, with reference to FIGS. 1 and 2, the principle of the spin orbit torque type magnetization rotation element 1 will be described.

As shown in FIG. 1, when a current I is applied to the spin track torque wiring layer 2, the first spin S1 and the second spin S2 are bent by the spin Hall effect. As a result, a pure spin current J _S is generated in the Z direction.

  In FIG. 1, since the first ferromagnetic layer 4 is disposed stacked in the Z direction in the spin track torque wiring layer, the pure spin current diffuses into the first ferromagnetic layer 4 and flows. That is, spins are injected into the first ferromagnetic layer 4. The injected spin gives a spin orbit torque (SOT) to the magnetization 8 of the first ferromagnetic layer 4 to cause magnetization rotation. In FIGS. 1 and 2, the magnetization 8 of the first ferromagnetic layer 4 is schematically represented as one magnetization located at the center of gravity of the first ferromagnetic layer 4.

  When the direction of spin injected into the ferromagnetic layer and the direction of magnetization are orthogonal, it is necessary to disturb the magnetization symmetry by applying an external magnetic field in order to cause magnetization rotation. However, in the spin orbit type magnetization rotating device 1 shown in FIG. 1, the direction of the spins injected from the spin orbit torque wiring layer 2 to the first ferromagnetic layer 4 is oriented in the Y direction, The direction of magnetization 8 of the magnetic layer 4 is inclined with respect to both the X direction and the Y direction, and has an X direction component and a Y direction component. Therefore, since the magnetization 8 has a Y-direction component not orthogonal to the direction of spin, magnetization rotation can be realized without applying an external magnetic field. If the application of the external magnetic field is not required, energy consumption can be reduced and the integration degree of the device can be improved. In addition, since the magnetization 8 has an X-direction component, the spin orbit type magnetization rotation element 1 shown in FIG. 1 can reduce the time required for the magnetization rotation, unlike the case where the magnetization 8 extends in the Y direction. It is suitable for high speed operation. Further, unlike the conventional XY-type magnetization rotating element shown in FIG. 11, the major axis of the first ferromagnetic layer 4 is disposed along the X direction, so the width of the spin orbit torque wiring layer 2 in the Y direction is It can be reduced. Therefore, the XY-type magnetization rotation element can be realized without reducing the current density, that is, without increasing the current.

(Manufacturing method of spin orbit torque type magnetization rotating element)
FIG. 3 is a plan view schematically showing a method of manufacturing a spin orbiting torque type magnetization rotating element according to an embodiment of the present invention. First, the spin track torque wiring layer 2 is fabricated on a substrate to be a support. The spin orbit torque wiring layer 2 can be manufactured using a known film forming means such as sputtering.

Next, the first ferromagnetic layer 4 is fabricated. The first ferromagnetic layer 1 can be manufactured using a known film forming means such as sputtering. However, if the first ferromagnetic layer 4 is simply formed into a film and has a long axis along the X direction, the easy magnetization axis also extends in the X direction due to shape anisotropy, so the XY type magnetization rotating element Can not realize. Therefore, as shown in FIG. 3, the first ferromagnetic layer 4 is formed while applying a magnetic field B _y having a Y direction component from the outside. Then, the easy magnetization axis of the first ferromagnetic layer 4 is inclined with respect to both the X direction and the Y direction by the action of the shape anisotropy and the magnetic field B _y .

Further, when forming the first ferromagnetic layer 4, the magnetic field B _y is not applied, and after forming the first ferromagnetic layer 4, a predetermined temperature, for example 250, is applied while applying the magnetic field B _y having a Y direction component. Annealing at a temperature of about 400 ° C. provides a tilted easy axis of magnetization in both the X and Y directions. In addition, after forming the first ferromagnetic layer 4 by applying a magnetic field B _y having a Y-direction component when forming the first ferromagnetic layer 4 and further applying a magnetic field B _y having a Y-direction component, Annealing, for example, at a temperature of 250 to 400.degree.

(Spin orbit torque type magnetoresistance effect element according to the first embodiment)
FIG. 4 is a cross-sectional view schematically showing a spin orbit torque type magnetoresistance effect device 101 according to the first embodiment of the present invention, and FIG. 5 is a sectional view showing the spin orbit torque type magnetoresistance effect device 101 according to FIG. It is the top view shown typically. FIG. 6 is a plan view schematically showing a state in which the magnetization is reversed in the spin orbit torque type magnetoresistive effect element 101 according to FIG.

  The spin orbit torque type magnetoresistance effect element 101 is stacked in the Z direction perpendicular to the X direction on the spin orbit torque wiring layer 102 having the major axis extending in the X direction and the spin orbit torque wiring layer 102. A spin-orbit torque type magnetization rotation element including the first ferromagnetic layer 104 disposed, and the first ferromagnetic layer 104 disposed on the opposite side of the spin-orbit torque wiring layer 102, and the magnetization direction is fixed And the nonmagnetic layer 110 disposed between the first ferromagnetic layer 104 and the second ferromagnetic layer 112. The configuration of the spin orbit torque type magnetization rotation element is the same as the configuration of the spin orbit torque type magnetization rotation element 1 described with reference to FIGS. 1 and 2, and thus the detailed description will be omitted.

<Second ferromagnetic layer>
The spin orbit torque type magnetoresistance effect element 101 functions by fixing the magnetization of the second ferromagnetic layer 112 in one direction and changing the direction of the magnetization of the first ferromagnetic layer 104 relatively. In the case of application to a coercivity difference type (pseudo-spin valve type) MRAM, the coercivity of the second ferromagnetic layer 112 is larger than the coercivity of the first ferromagnetic layer 104. When applied to an exchange bias type (spin valve type) MRAM, the magnetization direction of the second ferromagnetic layer 112 is fixed by exchange coupling with an antiferromagnetic layer.

  The spin orbit torque type magnetoresistance effect element 101 is a tunneling magnetoresistance (TMR) element when the nonmagnetic layer 110 is made of an insulator, and a giant magnetic field when the nonmagnetic layer 110 is made of a metal. It is a resistance (GMR: Giant Magnetoresistance) element.

  The lamination structure of the spin orbit torque type magnetoresistance effect element 101 can adopt the lamination structure of a known spin orbit torque type magnetoresistance effect element. For example, each layer may be composed of a plurality of layers, or may be provided with another layer such as an antiferromagnetic layer for fixing the magnetization direction of the second ferromagnetic layer 112. The second ferromagnetic layer 112 is called a fixed layer or a reference layer, and the first ferromagnetic layer 102 is called a free layer or a storage layer.

  The second ferromagnetic layer 112 has a major axis along the X direction. The direction of magnetization 114 can be various directions, but may be parallel to the magnetization easy axis (direction along magnetization 108) of the first ferromagnetic layer 104, for example, as shown in FIG. , Along the X direction.

  A known material can be used as the material of the second ferromagnetic layer 112, and the same material as the first ferromagnetic layer 104 can be used. Since the first ferromagnetic layer 104 is an in-plane magnetization film, the second ferromagnetic layer 112 is also preferably an in-plane magnetization film.

  Further, in order to further increase the coercive force of the second ferromagnetic layer 112 to the first ferromagnetic layer 104, an antiferromagnetic material such as IrMn or PtMn may be used as a material in contact with the second ferromagnetic layer 112. Furthermore, in order to prevent the stray magnetic field of the second ferromagnetic layer 112 from affecting the first ferromagnetic layer 102, a synthetic ferromagnetic coupling structure may be used.

<Nonmagnetic layer>
For the nonmagnetic layer 110, known materials can be used. For example, when the nonmagnetic layer 110 is made of an insulator (in the case of a tunnel barrier layer), Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O ₄ or the like can be used as the material. In addition to these materials, materials in which a part of Al, Si, and Mg is substituted with Zn, Be, and the like can also be used. Among these, MgO and MgAl ₂ O ₄ are materials that can realize coherent tunneling, so spins can be injected efficiently. When the nonmagnetic layer 110 is made of metal, Cu, Au, Ag or the like can be used as the material. Furthermore, when the nonmagnetic layer 70 is made of a semiconductor, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) Se ₂ or the like can be used as the material.

  In addition, the spin orbit torque type magnetoresistance effect element 101 may have other layers. For example, an underlayer may be provided on the surface of the first ferromagnetic layer 104 opposite to the nonmagnetic layer 110, and a cap layer may be provided on the surface of the second ferromagnetic layer 112 opposite to the nonmagnetic layer 110. You may have.

(Principle of spin orbit torque type magnetoresistive element)
Next, the principle of the spin orbit torque type magnetoresistance effect element 101 will be described.

  FIG. 5 shows a plan view of a spin orbit torque type magnetoresistive element 101 having a second ferromagnetic layer 112 in which the magnetization 114 is along the magnetization 108. The magnetization 108 of the first ferromagnetic layer 104 is inclined with respect to both the X direction and the Y direction. In FIG. 5, the direction of the magnetization 108 is parallel to the magnetization 114 of the second ferromagnetic layer 112 and the direction is the same. ing. In this case, the electrical resistance between the first ferromagnetic layer 104 and the second ferromagnetic layer 112 is in a low resistance state.

  FIG. 6 shows a plan view of the spin orbit torque type magnetoresistance effect element 101 in which the magnetization 108 of the first ferromagnetic layer 104 is reversed in the opposite direction to that in FIG. As described in the principle of the spin orbit torque type magnetization rotation element, when the spin is injected from the spin orbit torque wiring layer 102 to the first ferromagnetic layer 104, the magnetization 108 is rotated and reversed. Then, the magnetization 108 is parallel to the magnetization 114 of the second ferromagnetic layer 112 and opposite in direction (antiparallel). In this case, the electrical resistance between the first ferromagnetic layer 104 and the second ferromagnetic layer 112 is in a high resistance state. Therefore, depending on whether the orientations of the magnetization 108 and the magnetization 114 are parallel or antiparallel, the spin orbit torque type magnetoresistance effect element 101 can be formed between the first ferromagnetic layer 104 and the second ferromagnetic layer 112. It works as a magnetic memory that holds 0/1 data corresponding to the state of electrical resistance.

  Here, the case where the magnetization 114 of the second ferromagnetic layer 112 is inclined in the X direction and the Y direction has been described as an example. In this case, the magnetization 108 of the first ferromagnetic layer 104 and the magnetization 114 of the second ferromagnetic layer 112 are completely parallel or completely antiparallel. That is, the MR ratio of the spin orbit torque type magnetoresistance effect element 101 can be further increased. However, the magnetization 114 of the second ferromagnetic layer 112 may be along the X direction based on the shape anisotropy of the second ferromagnetic layer 112. Even in this case, the X-direction component of the magnetization 108 of the first ferromagnetic layer 104 can be parallel or antiparallel to the magnetization 114 of the second ferromagnetic layer 112, and acts as a magnetic memory. Can.

(Spin orbit torque type magnetoresistive effect element according to the second embodiment)
FIG. 7 is a cross-sectional view schematically showing a spin orbit torque type magnetoresistive effect element 201 according to a second embodiment of the present invention. In the spin orbit torque type magnetoresistive element 201, the first ferromagnetic layer 204 may have a diffusion preventing layer 216. The diffusion preventing layer 216 may be provided on the surface of the first ferromagnetic layer 204 on the nonmagnetic layer 210 side, or may be provided on any part of the first ferromagnetic layer 204 in the thickness direction. . In the latter case, the first ferromagnetic layer has a three-layer structure of a lower layer, a diffusion prevention layer, and an upper layer. The other configuration is the same as that of the spin orbit torque type magnetoresistive effect element 101 according to the first embodiment, and thus the detailed description will be omitted.

<Diffusion prevention layer>
As a material of the diffusion prevention layer 216, nonmagnetic heavy metal can be used. For example, as in the case of realizing the first ferromagnetic layer 204 having magnetization inclined to both the X direction and the Y direction, when annealing is performed, the second ferromagnetic layer from the inside of the first ferromagnetic layer 204 Elemental diffusion to 212 can occur and degrade the magnetic properties. However, when the diffusion prevention layer 216 is disposed in the first ferromagnetic layer 204, even if annealing is performed at a high temperature after the formation of the first ferromagnetic layer and the second ferromagnetic layer, the first ferromagnetic layer The occurrence of element diffusion from the inside of the layer 204 to the second ferromagnetic layer 212 can be suppressed, and the magnetic characteristics do not deteriorate.

  In addition, the diffusion prevention layer 216 may contain nonmagnetic heavy metal. Since elements of the heavy metal are hard to move even by annealing, the first ferromagnetic layer 204 and the second ferromagnetic layer 212 may be annealed even at high temperature after the formation of the first ferromagnetic layer and the second ferromagnetic layer. Element diffusion is suppressed. As a result, deterioration of the magnetic properties of the first ferromagnetic layer 204 and the second ferromagnetic layer 212 can be suppressed.

  The diffusion prevention layer 216 can have a thickness equal to or less than twice the ion radius of the constituent elements. In the case of such a thickness, strictly, heavy metal elements are scattered like islands, and the upper or lower layer and the mixed layer of heavy metal elements become a diffusion preventing layer.

(Spin orbit torque type magnetoresistive effect element according to the third embodiment)
FIG. 8 is a cross-sectional view schematically showing a spin orbit torque type magnetoresistive effect element 301 according to a third embodiment of the present invention, and FIG. 9 is a spin orbit torque type magnetoresistive effect element 301 according to FIG. It is the top view which showed typically. The spin orbit torque type magnetoresistance effect element 301 includes a third ferromagnetic layer 318 disposed between the first ferromagnetic layer 304 and the nonmagnetic layer 310. The other configuration is the same as that of the spin orbit torque type magnetoresistive effect element 301 according to the second embodiment, and thus the detailed description will be omitted. Although FIG. 8 shows the configuration in which the first ferromagnetic layer 304 has the diffusion prevention layer 316, the diffusion prevention layer 316 may be omitted.

  As a material of the third ferromagnetic layer 318, CoFeB, CoB, FeB can be used. Also, the third ferromagnetic layer 318 has a magnetization 320 along a direction parallel to the magnetization 308 of the first ferromagnetic layer 304. When the third ferromagnetic layer 318 is disposed between the first ferromagnetic layer 304 and the nonmagnetic layer 310, the first ferromagnetic layer 304 and the third ferromagnetic layer 318 are magnetically coupled, It becomes possible to rotate as one magnetization. Therefore, disposing the third ferromagnetic layer 318 has an effect of increasing the magnetoresistance effect.

(Magnetic Recording Array According to Fourth Embodiment)
FIG. 10 is a plan view of the magnetic recording array 400 according to the fourth embodiment. In the magnetic recording array 400 shown in FIG. 10, spin orbit torque type magnetoresistance effect elements 101 are arranged in a 3 × 3 matrix. FIG. 10 is an example of a magnetic recording array, and the type, number and arrangement of spin orbit torque type magnetoresistive elements 101 are arbitrary. Further, the control unit may exist over all the spin orbit torque type magnetoresistive effect elements 101 or may be provided for each spin orbit torque type magnetoresistive effect element 101.

  In the domain wall displacement type magnetic recording element 100, one word line WL1 to WL3, one bit line BL1 to BL3, and one read line RL1 to RL3 are connected.

 By selecting the word lines WL1 to WL3 and the bit lines BL1 to BL3 to which a current is to be applied, a pulse current is caused to flow through the first ferromagnetic layer 104 of any spin orbit torque type magnetoresistance effect element 101 to perform a write operation. Further, by selecting the read lines RL1 to RL3 and the bit lines BL1 to BL3 to which the current is applied, the current flows in the stacking direction of any spin orbit torque type magnetoresistance effect element 101, and the reading operation is performed. The word lines WL1 to WL3, the bit lines BL1 to BL3, and the read lines RL1 to RL3 to which current is applied can be selected by transistors or the like. When each spin orbit torque type magnetoresistance effect element 101 records information in multiple values, high capacity of the magnetic recording array can be realized.

  Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention as set forth in the appended claims. It is possible to change and change

Here, in the spin orbit torque type magnetization rotation element shown in FIG. 12, the first ferromagnetic layer 14 is circular in a plan view from the z direction. Since the shape in plan view is circular, it does not have shape anisotropy.
However, the direction of the magnetization 18 of the first ferromagnetic layer 14 is inclined with respect to both the X direction and the Y direction, and has an X direction component and a Y direction component. Therefore, since the magnetization 18 has a Y-direction component that is not orthogonal to the direction of spin, magnetization rotation can be realized without applying an external magnetic field also in this configuration. Even in the case where the magnetization easy direction of the magnetization 18 does not have shape anisotropy, it can be freely set by applying a magnetic field during film formation or annealing. The effect accompanying this configuration is not limited to the spin orbit torque type magnetization rotation element, and the same applies to the spin orbit torque type magnetoresistive effect element.

DESCRIPTION OF SYMBOLS 1 ... Spin track torque type magnetization rotation element, 2, 102, 202, 302, 502 ... Spin torque wiring layer, 4, 104, 204, 304, 504 ... 1st ferromagnetic layer, 6, 106, 206, 306, 506 ... Electrodes 108, 208, 308, 508 ... Magnetic easy axis of the first ferromagnetic layer 110, 210, 310 ... Nonmagnetic layer 112, 212, 312 ... Second ferromagnetic layer 114, 314 ... Second strong Magnetization of magnetic layer 216, 316: diffusion prevention layer 318: third ferromagnetic layer 320: magnetization of third ferromagnetic layer S1: first spin, S2: second spin, I: current, Js: pure Spin current

Claims (10)

A spin track torque wiring layer extending in the X direction,
A first ferromagnetic layer stacked on the spin track torque wiring layer;
Equipped with
The first ferromagnetic layer has shape anisotropy and has a major axis in the X direction,
The magnetization easy axis of the first ferromagnetic layer is inclined with respect to the X direction and a Y direction orthogonal to the X direction in a plane in which the spin orbit torque wiring layer extends.
Spin orbit torque type magnetization rotation element.   The spin orbiting torque type magnetization rotation element according to claim 1, wherein the first ferromagnetic layer is a HoCo alloy, a SmFe alloy, a FePt alloy, a CoPt alloy or a CoCrPt alloy. A spin orbit torque type magnetization rotation element according to claim 1 or 2;
A second ferromagnetic layer disposed on the side opposite to the spin orbit torque wiring layer of the first ferromagnetic layer and having a fixed direction of magnetization;
A nonmagnetic layer disposed between the first ferromagnetic layer and the second ferromagnetic layer;
, A spin orbit torque type magnetoresistive effect element.   The spin orbit torque type magnetoresistive effect element according to claim 3, further comprising a third ferromagnetic layer disposed between the first ferromagnetic layer and the nonmagnetic layer.   The spin orbit torque type magnetoresistive effect element according to claim 3 or 4, wherein the first ferromagnetic layer comprises a diffusion prevention layer on a surface of the first ferromagnetic layer on the nonmagnetic layer side.   The spin orbit torque type magnetoresistive effect element according to claim 5, wherein the diffusion prevention layer contains a nonmagnetic heavy metal.   The spin orbit torque type magnetoresistive effect element according to claim 5 or 6, wherein the diffusion preventing layer has a thickness equal to or less than twice an ion radius of an element constituting the diffusion preventing layer.   The method of manufacturing a spin orbiting torque type magnetization rotating device according to claim 1 or 2, wherein at least the first ferromagnetic layer is deposited in a state where a magnetic field is applied in a direction including the Y direction. The manufacturing method of an orbital torque type magnetization rotation element.   9. The method according to claim 8, further comprising the step of annealing in a state where a magnetic field is applied in a direction including the Y direction after depositing at least the first ferromagnetic layer.   The method of manufacturing a spin orbiting torque type magnetization rotating device according to claim 1, wherein after forming the first ferromagnetic layer at least, annealing is performed in a state where a magnetic field is applied in a direction including the Y direction. A method of manufacturing a spin orbit torque type magnetization rotating element.

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