Spin transfer torque structure for MRAM devices having a spin current injection capping layer
A magnetoresistive random-access memory (MRAM) device is disclosed. The device described herein has a spin current injection capping layer between the free layer of a magnetic tunnel junction and the orthogonal polarizer layer. The spin current injection capping layer maximizes the spin torque through very efficient spin current injection from the polarizer. The spin current injection capping layer can be comprised of a layer of MgO and a layer of a ferromagnetic material.
1. A magnetic device, comprising
a synthetic antiferromagnetic structure in a first plane, the synthetic antiferromagnetic structure including a magnetic reference layer, the magnetic reference layer having a magnetization vector,
a non-magnetic tunnel barrier layer in a second plane and disposed over the magnetic reference layer;
a free magnetic layer in a third plane disposed over the non-magnetic tunnel barrier layer, the free magnetic layer having a magnetization vector and having a magnetization direction that can precess from a first magnetization direction to a second magnetization direction, the free magnetic layer, the non-magnetic tunnel barrier layer and the magnetic reference layer forming a magnetic tunnel junction;
a spin current injection capping layer in a fourth plane, the spin current injection capping layer disposed over the free magnetic layer, the spin current injection capping layer comprising a non-magnetic insulator layer over the free magnetic layer and a magnetic conductor layer over the non-magnetic insulator layer; and
a magnetic polarizer layer that polarizes electrons passing therethrough to create spin polarized current, the magnetic polarizer layer having at least one magnetic vector, the at least one magnetic vector being orthogonal to the magnetization vector of the magnetic reference layer and the magnetization vector of the free magnetic layer;
wherein the spin current injection capping layer is between the magnetic polarizer layer and the free magnetic layer and wherein the spin current injection capping layer injects the spin polarized current into the magnetic tunnel junction through tunneling between the magnetic conductor layer and the free magnetic layer.
2. The magnetic device of claim 1 wherein the free magnetic layer comprises of a layer of CoFeB with a thickness of 0.8 nm to 5 nm.
3. The magnetic device of claim 1 wherein the non-magnetic insulator layer of the spin current injection capping layer comprises a layer of MgO having a thickness of 0.3 nm to 1.5 nm.
4. The magnetic device of claim 1 wherein the magnetic conductor layer of the spin current injection capping layer is comprised of high spin polarization material.
5. The magnetic device of claim 4 wherein the high spin polarization material comprises Co (cobalt), Fe (iron), CoFe (cobalt iron), or CoFeB (cobalt iron boron) having a thickness of 0.5 nm to 1nm.
6. The magnetic device of claim 1 , further comprising an insertion layer, the insertion layer being disposed in between the free magnetic layer and the non-magnetic tunnel barrier layer.
7. The magnetic device of claim 6 , wherein the insertion layer comprises an Fe film having a thickness of 0.2 nm to 0.5 nm.
8. The magnetic device of claim 1 wherein the at least one magnetic vector of the magnetic polarizer layer comprises magnetic vector with a direction that is fixed.
9. A magnetic device, comprising
a synthetic antiferromagnetic structure in a first plane, the synthetic antiferromagnetic structure including a magnetic reference layer, the magnetic reference layer having a magnetization vector,
a non-magnetic tunnel barrier layer in a second plane and disposed over the magnetic reference layer;
a free magnetic layer in a third plane disposed over the non-magnetic tunnel barrier layer, the free magnetic layer having a magnetization vector and having a magnetization direction that can precess from a first magnetization direction to a second magnetization direction, the free magnetic layer, the non-magnetic tunnel barrier layer and the magnetic reference layer forming a magnetic tunnel junction; and
a spin current injection capping layer in a fourth plane, the spin current injection capping layer disposed over the free magnetic layer, the spin current injection capping layer comprising a non-magnetic insulator layer over the free magnetic layer and a magnetic conductor layer over the non-magnetic insulator layer, wherein the spin current injection capping layer injects the spin polarized current into the magnetic tunnel junction through tunneling.
10. The magnetic device of claim 9 wherein the free magnetic layer comprises of a layer of CoFeB with a thickness of 0.8 nm to 5 nm.
11. The magnetic device of claim 9 wherein the non-magnetic insulator layer of the spin current injection capping layer comprises a layer of MgO having a thickness of 0.3 nm to 1.5 nm.
12. The magnetic device of claim 9 wherein the magnetic conductor layer of the spin current injection capping layer is comprised of high spin polarization material.
13. The magnetic device of claim 12 wherein the high spin polarization material comprises Co (cobalt), Fe (iron), CoFe (cobalt iron), or CoFeB (cobalt iron boron) having a thickness of 0.5 nm to 1.5 nm.
14. The magnetic device of claim 9 , further comprising an insertion layer, the insertion layer being disposed in between the free magnetic layer and the non-magnetic tunnel barrier layer.
15. The magnetic device of claim 14 , wherein the insertion layer comprises an Fe film having a thickness of 0.2 nm to 0.5 nm.
16. A magnetic device, comprising
a magnetic reference layer in a first plane, the magnetic reference layer having a magnetization vector,
a non-magnetic tunnel barrier layer in a second plane and disposed over the magnetic reference layer;
a free magnetic layer in a third plane disposed over the non-magnetic tunnel barrier layer, the free magnetic layer having a magnetization vector and having a magnetization direction that can precess from a first magnetization direction to a second magnetization direction, the free magnetic layer, the non-magnetic tunnel barrier layer and the magnetic reference layer forming a magnetic tunnel junction;
a spin current injection capping layer in a fourth plane, the spin current injection capping layer disposed over the free magnetic layer, the spin current injection capping layer comprising a non-magnetic insulator layer over the free magnetic layer and a magnetic conductor layer over the non-magnetic insulator layer; and
a magnetic polarizer layer that polarizes electrons passing therethrough to create spin polarized current, the magnetic polarizer layer having at least one magnetic vector, the at least one magnetic vector being orthogonal to the magnetization vector of the magnetic reference layer and the magnetization vector of the free magnetic layer;
wherein the spin current injection capping layer is between the magnetic polarizer layer and the free magnetic layer and wherein the spin current injection capping layer injects the spin polarized current into the magnetic tunnel junction through tunneling between the magnetic conductor layer and the free magnetic layer.
17. The magnetic device of claim 16 wherein the free magnetic layer comprises of a layer of CoFeB with a thickness of 0.8 nm to 5 nm.
18. The magnetic device of claim 16 wherein the non-magnetic insulator layer of the spin current injection capping layer comprises a layer of MgO having a thickness of 0.3 nm to 1.5 nm.
19. The magnetic device of claim 16 wherein the magnetic conductor layer of the spin current injection capping layer is comprised of high spin polarization material.
20. The magnetic device of claim 19 wherein the high spin polarization material comprises Co (cobalt), Fe (iron), CoFe (cobalt iron), or CoFeB (cobalt iron boron) having a thickness of 0.5 nm to 1 nm.
21. The magnetic device of claim 16 , further comprising an insertion layer, the insertion layer being disposed in between the free magnetic layer and the non-magnetic tunnel barrier layer.
22. The magnetic device of claim 21 , wherein the insertion layer comprises an Fe film having a thickness of 0.2 nm to 0.5 nm.
23. The magnetic device of claim 16 wherein the at least one magnetic vector of the magnetic polarizer layer comprises magnetic vector with a direction that is fixed.