Magnetic memory device
According to one embodiment, a magnetic memory device includes a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction, and a nonmagnetic layer between the first magnetic layer and the second magnetic layer, wherein the first magnetic layer includes a first sub-magnetic layer, a second sub-magnetic layer, and a first intermediate layer between the first sub-magnetic layer and the second sub-magnetic layer, and the first sub-magnetic layer is provided between the nonmagnetic layer and the second sub-magnetic layer and has a magnetization direction antiparallel to a magnetization direction of the second sub-magnetic layer and has a magnetization amount smaller than that of the second sub-magnetic layer.
1. A magnetic memory device comprising:
a first magnetic layer having a variable magnetization direction;
a second magnetic layer having a fixed magnetization direction; and
a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer,
wherein:
the first magnetic layer includes a first sub-magnetic layer, a second sub-magnetic layer, a third sub-magnetic layer, a first intermediate layer provided between the first sub-magnetic layer and the second sub-magnetic layer, and a second intermediate layer provided between the second sub-magnetic layer and the third sub-magnetic layer,
the first sub-magnetic layer is provided between the nonmagnetic layer and the second sub-magnetic layer and has a magnetization direction that is antiparallel to a magnetization direction of the second sub-magnetic layer and has a magnetization amount that is smaller than a magnetization amount of the second sub-magnetic layer,
the third sub-magnetic layer has a magnetization direction that is antiparallel to the magnetization direction of the second sub-magnetic layer, and
the second sub-magnetic layer is provided between the first sub-magnetic layer and the third sub-magnetic layer.
2. The device according to claim 1 , wherein the third sub-magnetic layer has a magnetization amount that is smaller than the magnetization amount of the second sub-magnetic layer.
3. The device according to claim 1 , wherein a sum of the magnetization amount of the first sub-magnetic layer and a magnetization amount of the third sub-magnetic layer is equal to the magnetization amount of the second sub-magnetic layer.
4. The device according to claim 1 , further comprising:
a third magnetic layer having a fixed magnetization direction that is antiparallel to the magnetization direction of the second magnetic layer, the third magnetic layer canceling a magnetic field applied from the second magnetic layer to the first magnetic layer.
5. The device according to claim 1 , wherein the first sub-magnetic layer and the second sub-magnetic layer contain at least cobalt (Co).
6. The device according to claim 1 , wherein the first intermediate layer contains at least one element selected from ruthenium (Ru), rhodium (Rh), osmium (Os), and iridium (Ir).
7. A magnetic memory device comprising:
a first magnetic layer having a variable magnetization direction;
a second magnetic layer having a fixed magnetization direction; and
a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer,
wherein:
the first magnetic layer includes a first sub-magnetic layer, a second sub-magnetic layer, a third sub-magnetic layer, a first intermediate layer provided between the first sub-magnetic layer and the second sub-magnetic layer, and a second intermediate layer provided between the second sub-magnetic layer and the third sub-magnetic layer,
the first sub-magnetic layer is provided between the nonmagnetic layer and the second sub-magnetic layer and has a magnetization direction that is antiparallel to a magnetization direction of the second sub-magnetic layer and has a thickness that is smaller than a thickness of the second sub-magnetic layer,
the third sub-magnetic layer has a magnetization direction that is antiparallel to the magnetization direction of the second sub-magnetic layer, and
the second sub-magnetic layer is provided between the first sub-magnetic layer and the third sub-magnetic layer.
8. The device according to claim 7 , wherein the third sub-magnetic layer has a thickness that is smaller than the thickness of the second sub-magnetic layer.
9. The device according to claim 7 , further comprising:
a third magnetic layer having a fixed magnetization direction that is antiparallel to a magnetization direction of the second magnetic layer, the third magnetic layer canceling a magnetic field applied from the second magnetic layer to the first magnetic layer.
10. The device according to claim 7 , wherein the first sub-magnetic layer and the second sub-magnetic layer contain at least cobalt (Co).
11. The device according to claim 7 , wherein the first intermediate layer contains at least one element selected from ruthenium (Ru), rhodium (Rh), osmium (Os), and iridium (Ir).
12. A magnetic memory device comprising:
a first magnetic layer having a variable magnetization direction;
a second magnetic layer having a fixed magnetization direction; and
a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer,
wherein:
the first magnetic layer includes a first sub-magnetic layer, a second sub-magnetic layer, a third sub-magnetic layer, a first intermediate layer provided between the first sub-magnetic layer and the second sub-magnetic layer, and a second intermediate layer provided between the second sub-magnetic layer and the third sub-magnetic layer,
the first sub-magnetic layer is provided between the nonmagnetic layer and the second sub-magnetic layer and has a magnetization direction that is antiparallel to a magnetization direction of the second sub-magnetic layer and has a saturation magnetization that is smaller than a saturation magnetization of the second sub-magnetic layer,
the third sub-magnetic layer has a magnetization direction that is antiparallel to the magnetization direction of the second sub-magnetic layer, and
the second sub-magnetic layer is provided between the first sub-magnetic layer and the third sub-magnetic layer.
13. The device according to claim 12 , wherein the third sub-magnetic layer has a saturation magnetization that is smaller than the saturation magnetization of the second sub-magnetic layer.
14. The device according to claim 12 , further comprising:
a third magnetic layer having a fixed magnetization direction that is antiparallel to a magnetization direction of the second magnetic layer, the third magnetic layer canceling a magnetic field applied from the second magnetic layer to the first magnetic layer.
15. The device according to claim 12 , wherein the first sub-magnetic layer and the second sub-magnetic layer contain at least cobalt (Co).
16. The device according to claim 12 , wherein the first intermediate layer contains at least one element selected from ruthenium (Ru), rhodium (Rh), osmium (Os), and iridium (Ir).