Magnetic stack having reference layers with orthogonal magnetization orientation directions
View Patent ↗A magnetic cell includes a ferromagnetic free layer having a free magnetization orientation direction and a first ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction. A first oxide barrier layer is between the ferromagnetic free layer and the first ferromagnetic pinned reference layer. The magnetic cell further includes a second ferromagnetic pinned reference layer having a second reference magnetization orientation direction that is orthogonal to the first reference magnetization orientation direction. The ferromagnetic free layer is between the first ferromagnetic pinned reference layer and the second ferromagnetic pinned reference layer.
1. A magnetic cell comprising: a ferromagnetic free layer having a free magnetization orientation direction; a first synthetic anti-ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction; a first oxide barrier layer between the ferromagnetic free layer and the first synthetic anti-ferromagnetic pinned reference layer; and a second synthetic anti-ferromagnetic pinned reference layer having a second reference magnetization orientation direction that is orthogonal to the first reference magnetization orientation direction, the ferromagnetic free layer between the first synthetic anti-ferromagnetic pinned reference layer and the second synthetic anti-ferromagnetic pinned reference layer wherein the first synthetic anti-ferromagnetic pinned reference layer has a first blocking temperature and the second synthetic anti-ferromagnetic pinned reference layer has a second blocking temperature that is less than the first blocking temperature.
2. The magnetic cell of claim 1 wherein the ferromagnetic free layer, first synthetic anti-ferromagnetic pinned reference layer, and second synthetic anti-ferromagnetic pinned reference layer, have in-plane magnetic anisotropy.
3. The magnetic cell of claim 1 further comprising a second oxide barrier layer between the ferromagnetic free layer and the second synthetic anti-ferromagnetic pinned reference layer.
4. The magnetic cell of claim 1 wherein the ferromagnetic free layer switches between a high resistance data state and a low resistance data state due to spin torque transfer induced by a current passing through the magnetic cell.
5. The magnetic cell of claim 1 wherein the free magnetization orientation direction is orthogonal to the second reference magnetization orientation direction.
6. A spin torque transfer magnetic cell comprising:
a ferromagnetic free layer having an in-plane free magnetization orientation direction that switches between a high resistance data state and a low resistance data state due to spin torque transfer induced by a current passing through the magnetic cell;
a first synthetic anti-ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction;
a first oxide barrier layer between the ferromagnetic free layer and the first synthetic anti-ferromagnetic pinned reference layer;
a second synthetic anti-ferromagnetic pinned reference layer having an in-plane second reference magnetization orientation direction that is orthogonal to the free magnetization orientation direction; and
a second oxide barrier layer between the ferromagnetic free layer and the second synthetic anti-ferromagnetic pinned reference layer;
wherein the first synthetic anti-ferromagnetic pinned reference layer has a first blocking temperature and the second synthetic anti-ferromagnetic pinned reference layer has a second blocking temperature that is less than the first blocking temperature.
7. The spin torque transfer magnetic cell of claim 6 wherein the free magnetization orientation direction is orthogonal to the second reference magnetization orientation direction.
8. A spin torque transfer magnetic cell comprising:
a ferromagnetic free layer having an in-plane free magnetization orientation direction that switches between a high resistance data state and a low resistance data state due to spin torque transfer induced by a current passing through the magnetic cell;
a first synthetic anti-ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction;
a first oxide barrier layer between the ferromagnetic free layer and the first synthetic anti-ferromagnetic pinned reference layer;
a second synthetic anti-ferromagnetic pinned reference layer having an in-plane second reference magnetization orientation direction that is orthogonal to the first reference magnetization orientation direction; and
a second oxide barrier layer between the ferromagnetic free layer and the second synthetic anti-ferromagnetic pinned reference layer;
wherein the first synthetic anti-ferromagnetic element has a first blocking temperature and the second synthetic anti-ferromagnetic element has a second blocking temperature that is less than the first blocking temperature.