MRAM cells including coupled free ferromagnetic layers for stabilization
View Patent ↗A free ferromagnetic data storage layer of an MRAM cell is coupled to a free ferromagnetic stabilization layer, which stabilization layer is directly electrically coupled to a contact electrode, on one side, and is separated from the free ferromagnetic data storage layer, on an opposite side, by a spacer layer. The spacer layer provides for the coupling between the two free layers, which coupling is one of: a ferromagnetic coupling and an antiferromagnetic coupling.
1. An MRAM cell comprising:
a pinned layer having a predetermined magnetic orientation set by an adjacent antiferromagnetic pinning layer;
a spacer layer disposed between the pinned layer and a free ferromagnetic data storage layer; and
a multi-layered coupling layer disposed between the data storage layer and a free ferromagnetic stabilization layer, the coupling layer ferromagnetically coupling the data storage layer and stabilization layer in an anti-parallel magnetic relationship.
2. The MRAM cell of claim 1 , further comprising a first electrode contact layer coupled to the stabilization layer and a second electrode contact layer coupled to the antiferromagnetic pinning layer.
3. The MRAM cell of claim 1 , wherein the pinned layer comprises a synthetic antiferromagnetic coupled structure.
4. The MRAM cell of claim 1 , wherein the coupling layer further provides for spin depolarization.
5. The MRAM cell of claim 1 , wherein the coupling layer comprises an antiferromagnetic material.
6. The MRAM cell of claim 1 , wherein the coupling layer comprises a paramagnetic material.
7. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer and a second paramagnetic sub-layer, the second sub-layer being directly adjacent the stabilization layer.
8. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer and a second paramagnetic sub-layer, the second sub-layer having a thickness that is less than that of the first sub-layer.
9. The MRAM cell of claim 8 , wherein the second sub-layer is formed by doping a portion of the first sub-layer with a magnetic material.
10. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer and a second paramagnetic sub-layer, the second sub-layer being directly adjacent the data storage layer.
11. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer and a second paramagnetic sub-layer which achieves ferromagnetic coupling from interface roughness.
12. The MRAM cell of claim 11 , wherein Neel coupling arises from the interface roughness.
13. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first paramagnetic sub-layer, a second non-magnetic sub-layer and a third paramagnetic sub-layer, the second sub-layer extending between the first and third sub-layers.
14. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first paramagnetic sub-layer, a second non-magnetic sub-layer and a third paramagnetic sub-layer,
the first and third sub-layers each have a thickness that is less than that of the second sub-layer.
15. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer, a second paramagnetic sub-layer and a third non-magnetic sub-layer, the second sub-layer extending between the first and third sub-layers.
16. The MRAM cell of claim 1 , wherein:
the coupling layer includes a first non-magnetic sub-layer, a second paramagnetic sub-layer and a third non-magnetic sub-layer, the second layer having a thickness that is less than each of the first and third sub-layers.
17. An MRAM cell comprising:
a pinned layer;
an antiferromagnetic pinning layer, which pins the pinned layer;
a free ferromagnetic data storage layer;
a first spacer layer extending between the data storage layer and the pinned layer, the first spacer layer being nonmagnetic;
a free ferromagnetic stabilization layer;
a first electrode contact layer directly electrically coupled to the stabilization layer; and
a second spacer layer extending alongside the stabilization layer, opposite the first electrode contact layer and between the stabilization layer and the data storage layer, the second spacer layer including a first sub-layer and a second sub-layer, the second sub-layer having a thickness that is less than that of the first sub-layer; and
wherein the second spacer layer is conductive and provides for one of ferromagnetic coupling and antiferromagnetic coupling between the data storage layer and the stabilization layer;
the first sub-layer of the second spacer layer comprises a non-magnetic material;
the second sub-layer of the second spacer layer comprises a paramagnetic material and is formed by doping a portion of the first sub-layer with a magnetic material; and
a strength of the coupling between the data storage layer and the stabilization layer is greater than a coercivity of the stabilization layer.
18. The MRAM cell of claim 17 , further comprising a second electrode contact layer directly coupled to the antiferromagnetic pinning layer.
19. A memory element comprising:
a pinned layer having a predetermined magnetic orientation set by an adjacent pinning layer;
a spacer layer disposed between the pinned layer and a free ferromagnetic data storage layer; and
a multi-layered coupling layer disposed between the data storage layer and a free ferromagnetic stabilization layer, the coupling layer comprising at least one non-magnetic layer and at least one magnetic layer.
20. The memory element of claim 19 , wherein the non-magnetic layer has a greater thickness than the magnetic layer.