Spin valve element, method of driving the same, and storage device using the same
Provided is a spin valve element capable of performing multi-value recording, which includes a pair of ferromagnetic layers having different coercivities from each other, and sandwiching an insulating layer or a non-magnetic layer. The ferromagnetic layer having the smaller coercivity has a substantially circular in-plane profile, and a plurality of island-shaped non-magnetic portions I N , I E , I W , and I S are included. In addition, a storage device is manufactured by using such a spin valve element.
1. A spin valve element comprising:
an intermediate layer including an insulating layer or a non-magnetic layer; and
a pair of ferromagnetic layers sandwiching the intermediate layer, one of the pair of the ferromagnetic layers having a different coercivity from another of the pair,
wherein at least the ferromagnetic layer having a smaller coercivity than the other of the pair has a substantially circular in-plane profile and a plurality of island-shaped non-magnetic portions disposed thereon.
2. The spin valve element according to claim 1 , wherein an island-shaped non-magnetic portion has a substantially circular in-plane profile.
3. The spin valve element according to claim 1 , wherein the plurality of the island-shaped non-magnetic portions are disposed on a circle having substantially a same center as an outer shape of the spin valve element.
4. A method of driving the spin valve element according to claim 1 , comprising:
moving a vortex in a vortex-shaped magnetization from one island-shaped non-magnetic portion to another island-shaped non-magnetic portion by applying an in-plane magnetic field to the ferromagnetic layer having the smaller coercivity.
5. The method according to claim 4 , wherein a direction of the in-plane magnetic field is not aligned with a direction passing through two island-shaped non-magnetic portions.
6. A method of driving the spin valve element according to claim 1 , comprising:
moving a vortex in a vortex-shaped magnetization by applying a perpendicular magnetic field to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies at one island-shaped non-magnetic portion to a state where the vortex lies at another island-shaped non-magnetic portion.
7. A method of driving the spin valve element according to claim 1 , comprising:
moving a vortex in a vortex-shaped magnetization by causing a current to flow so as to allow spin injection from the ferromagnetic layer having a larger coercivity to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies in one island-shaped non-magnetic portion to a state where the vortex lies in a neighboring island-shaped non-magnetic portion.
8. A storage device using as a recording element the spin valve element according to claim 1 .
9. A method of driving the spin valve element according to claim 2 , comprising:
moving a vortex in a vortex-shaped magnetization from one island-shaped non-magnetic portion to another island-shaped non-magnetic portion by applying an in-plane magnetic field to the ferromagnetic layer having the smaller coercivity.
10. A method of driving the spin valve element according to claim 3 , comprising:
moving a vortex in a vortex-shaped magnetization from one island-shaped non-magnetic portion to another island-shaped non-magnetic portion by applying an in-plane magnetic field to the ferromagnetic layer having the smaller coercivity.
11. The method according to claim 9 , wherein a direction of the in-plane magnetic field is not aligned with a direction passing through two island-shaped non-magnetic portions.
12. The method according to claim 10 , wherein a direction of the in-plane magnetic field is not aligned with a direction passing through two island-shaped non-magnetic portions.
13. A method of driving the spin valve element according to claim 2 , comprising:
moving a vortex in a vortex-shaped magnetization by applying a perpendicular magnetic field to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies at one island-shaped non-magnetic portion to a state where the vortex lies at another island-shaped non-magnetic portion.
14. A method of driving the spin valve element according to claim 3 , comprising:
moving a vortex in a vortex-shaped magnetization by applying a perpendicular magnetic field to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies at one island-shaped non-magnetic portion to a state where the vortex lies at another island-shaped non-magnetic portion.
15. A method of driving the spin valve element according to claim 2 , comprising:
moving a vortex in a vortex-shaped magnetization by causing a current to flow so as to allow spin injection from the ferromagnetic layer having a larger coercivity to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies in one island-shaped non-magnetic portion to a state where the vortex lies in a neighboring island-shaped non-magnetic portion.
16. A method of driving the spin valve element according to claim 3 , comprising:
moving a vortex in a vortex-shaped magnetization by causing a current to flow so as to allow spin injection from the ferromagnetic layer having a larger coercivity to the ferromagnetic layer having the smaller coercivity, so that the vortex has a rotational motion from a state where the vortex lies in one island-shaped non-magnetic portion to a state where the vortex lies in a neighboring island-shaped non-magnetic portion.
17. A storage device using as a recording element the spin valve element according to claim 2 .
18. A storage device using as a recording element the spin valve element according to claim 3 .