Spin-orbit torque type magnetization reversal element, magnetic memory, and high frequency magnetic device
A spin-orbit torque type magnetization reversal element including a ferromagnetic metal layer with a varying magnetization direction; and spin-orbit torque wiring that extends in a first direction intersecting with a stacking direction of the ferromagnetic metal layer and that is joined to the ferromagnetic metal layer; wherein when viewed from the first direction, the spin-orbit torque wiring is asymmetrical in a second direction that is orthogonal to the first direction and the stacking direction, with respect to an axis that passes through a center, in the second direction, of the ferromagnetic metal layer.
1. A spin-orbit torque type magnetization reversal element comprising:
a ferromagnetic metal layer with a varying magnetization direction; and
spin-orbit torque wiring that extends in a first direction intersecting with a stacking direction of the ferromagnetic metal layer and that is joined to the ferromagnetic metal layer; wherein
when end portions of the spin-orbit torque wiring in a second direction that is orthogonal to the first direction and the stacking direction are defined as a first end portion and a second end portion; and of the end portions of the ferromagnetic metal layer in the second direction, the end portion on a side closer to the first end portion is defined as a third end portion and the end portion on a side closer to the second end portion is defined as a fourth end portion,
an area of a region of the spin-orbit torque wiring between the first end portion and the third end portion differs from an area of a region of the spin-orbit torque wiring between the second end portion and the fourth end portion in a cross section in a direction perpendicular to the first direction as viewed from the first direction, and
the spin-orbit torque wiring is configured to reverse the magnetization of the ferromagnetic metal layer by inducing spin orbit torque in the ferromagnetic metal layer.
2. The spin-orbit torque type magnetization reversal element according to claim 1 , wherein
an inclination angle of an end surface of the spin-orbit torque wiring from the first end portion toward the third end portion differs from an inclination angle of an end surface of the spin-orbit torque wiring from the second end portion toward the fourth end portion in a cross section in a direction perpendicular to the first direction as viewed from the first direction, and
the spin-orbit torque wiring is configured to reverse the magnetization of the ferromagnetic metal layer by inducing spin orbit torque in the ferromagnetic metal layer.
3. The spin-orbit torque type magnetization reversal element according to claim 1 , wherein:
a distance between the first end portion and the third end portion is different from a distance between the second end portion and the fourth end portion.
4. The spin-orbit torque type magnetization reversal element according to claim 3 , wherein
the distance between the first end portion and the third end portion and the distance between the second end portion and the fourth end portion are both greater than zero, and at least one of the distances is not more than a spin diffusion length of the spin-orbit torque wiring.
5. The spin-orbit torque type magnetization reversal element according to claim 1 , wherein,
when the spin-orbit torque wiring is viewed from the first direction, an area of a first region lying on a side towards a first end portion in the second direction, with respect to an axis, is different from an area of a second region lying on a side towards a second end portion, and
the axis is a straight line that passes through a center, in the second direction, of the ferromagnetic metal layer and extends in the stacking direction of the ferromagnetic metal layer.
6. The spin-orbit torque type magnetization reversal element according to claim 1 , wherein,
in the spin-orbit torque wiring, a material constituting a first part on a side towards a first end portion in the second direction, with respect to an axis, is different from a material constituting a second part lying on a side towards a second end portion, and
the axis is a straight line that passes through a center, in the second direction, of the ferromagnetic metal layer and extends in the stacking direction of the ferromagnetic metal layer.
7. The spin-orbit torque type magnetization reversal element according to claim 6 , wherein
the first part comprises a metal, and the second part comprises a semiconductor or an insulator.
8. The spin-orbit torque type magnetization reversal element according to claim 1 , wherein
the spin-orbit torque wiring is inclined in the second direction when viewed from the first direction.
9. The spin-orbit torque type magnetization reversal element according to claim 1 , further comprising a non-magnetic layer and a fixed layer with a fixed magnetization direction, on a surface on a side of the ferromagnetic metal layer opposite to the spin-orbit torque wiring.
10. A magnetic memory using the spin-orbit torque type magnetization reversal element according to claim 9 .
11. A high-frequency magnetic device using the spin-orbit torque type magnetization reversal element according to claim 9 .
12. A spin-orbit torque type magnetization reversal element comprising:
a ferromagnetic metal layer with a varying magnetization direction; and
spin-orbit torque wiring that extends in a first direction intersecting with a stacking direction of the ferromagnetic metal layer and that is joined to the ferromagnetic metal layer; wherein
when end portions of the spin-orbit torque wiring in a second direction that is orthogonal to the first direction and the stacking direction are defined as a first end portion and a second end portion; and of the end portions of the ferromagnetic metal layer in the second direction, the end portion on a side closer to the first end portion is defined as a third end portion and the end portion on a side closer to the second end portion is defined as a fourth end portion,
an inclination angle of an end surface of the spin-orbit torque wiring from the first end portion toward the third end portion differs from an inclination angle of an end surface of the spin-orbit torque wiring from the second end portion toward the fourth end portion in a cross section in a direction perpendicular to the first direction as viewed from the first direction, and
the spin-orbit torque wiring is configured to reverse the magnetization of the ferromagnetic metal layer by inducing spin orbit torque in the ferromagnetic metal layer.
13. The spin-orbit torque type magnetization reversal element according to claim 12 , wherein:
a distance between the first end portion and the third end portion is different from a distance between the second end portion and the fourth end portion.
14. The spin-orbit torque type magnetization reversal element according to claim 13 , wherein
the distance between the first end portion and the third end portion and the distance between the second end portion and the fourth end portion are both greater than zero, and at least one of the distances is not more than a spin diffusion length of the spin-orbit torque wiring.
15. The spin-orbit torque type magnetization reversal element according to claim 12 , wherein,
when the spin-orbit torque wiring is viewed from the first direction, an area of a first region lying on a side towards a first end portion in the second direction, with respect to an axis, is different from an area of a second region lying on a side towards a second end portion, and
the axis is a straight line that passes through a center, in the second direction, of the ferromagnetic metal layer and extends in the stacking direction of the ferromagnetic metal layer.
16. The spin-orbit torque type magnetization reversal element according to claim 12 , wherein,
in the spin-orbit torque wiring, a material constituting a first part on a side towards a first end portion in the second direction, with respect to an axis, is different from a material constituting a second part lying on a side towards a second end portion, and
the axis is a straight line that passes through a center, in the second direction, of the ferromagnetic metal layer and extends in the stacking direction of the ferromagnetic metal layer.
17. The spin-orbit torque type magnetization reversal element according to claim 16 , wherein
the first part comprises a metal, and the second part comprises a semiconductor or an insulator.
18. The spin-orbit torque type magnetization reversal element according to claim 12 , wherein
the spin-orbit torque wiring is inclined in the second direction when viewed from the first direction.
19. The spin-orbit torque type magnetization reversal element according to claim 12 , further comprising a non-magnetic layer and a fixed layer with a fixed magnetization direction, on a surface on a side of the ferromagnetic metal layer opposite to the spin-orbit torque wiring.
20. A magnetic memory using the spin-orbit torque type magnetization reversal element according to claim 19 .
21. A high-frequency magnetic device using the spin-orbit torque type magnetization reversal element according to claim 19 .