Magnetic memory having a pinning synthetic antiferromagnetic structure (SAF) with cobalt over platinum (Pt/Co) bilayers
A magnetic memory element for Magnetic Random Access Memory. The magnetic memory element has improved reference layer magnetic pinning and reduced dipole fringing field effect on the magnetic free layer. The magnetic memory element includes a magnetic reference layer having a pinned magnetization, a magnetic free layer having a switchable magnetization and a non-magnetic barrier layer between the magnetic reference layer and the magnetic free layer. The magnetic reference layer is exchange coupled with a synthetic anti-ferromagnetic structure that includes a first multi-layer structure, a second multi-layer structure and a non-magnetic anti-parallel exchange coupling layer located between the first and second multi-layer structures. Each of the first and second multi-layer structures includes a plurality of bi-layers of Pt and Co, with the Pt being deposited first and located below the Co.
1. A magnetic memory element, comprising:
a magnetic reference layer;
a magnetic free layer;
a non-magnetic barrier layer located between the magnetic free layer and the magnetic reference layer; and
a synthetic antiferromagnetic structure, further comprising:
a first multilayer structure comprising a plurality of bi-layers of Pt and Co;
a second multi-layer structure comprising a plurality of bi-layers of Pt and Co; and
a non-magnetic anti-parallel exchange coupling layer located between the first multi-layer structure and the second multilayer structure;
wherein each of the plurality of bi-layers of Pt and Co in each of the first and second multi-layer structures is configured so that the layer of Co is formed over the layer of Pt;
wherein the second multi-layer structure is exchange coupled with the magnetic reference layer.
2. The magnetic memory element as in claim 1 , wherein the first multi-layer structure is formed on an under-layer, and wherein a bi-layer of the first multi-layer structure is configured such that it has a layer of Pt in contact with the under-layer.
3. The magnetic memory element as in claim 1 , wherein the first multi-layer structure has a greater or equal number of Pt/Co bilayers than the second multi-layer structure.
4. The magnetic memory element as in claim 1 , wherein:
the first multi-layer structure has 5-9 Pt/Co bi-layers; and
the second multi-layer structure has 2-6 Pt/Co bi-layers.
5. The magnetic memory element as in claim 1 , wherein each of the first and second multi-layer structures has a perpendicular magnetic anisotropy.
6. The magnetic memory element as in claim 1 , wherein each of the first and second multi-layer structures has an effective perpendicular magnetization of at least 10 kGauss.
7. The magnetic memory element as in claim 1 , wherein each of the first and second multi-layer structures has a magnetization that is not greater than 1000 emu/cc.
8. The magnetic memory element as in claim 1 , wherein each of the first and second multi-layer structures has an effective perpendicular magnetization of at least 10 kGauss and has a magnetization not greater than 1000 emu/cc.
9. The magnetic memory element as in claim 1 , wherein the non-magnetic antiparallel exchange coupling layer comprises Ru.
10. The magnetic memory element as in claim 1 , wherein the magnetic reference layer comprises CoFeB.
11. The magnetic memory element as in claim 1 , further comprising a ferromagnetic coupling layer located between the second multi-layer structure and the magnetic reference layer.
12. The magnetic memory element as in claim 11 , wherein the ferromagnetic coupling layer comprises one or more materials of Co, W, Mo and Ta.
13. A magnetic memory element, comprising:
a magnetic reference layer;
a magnetic free layer;
a non-magnetic barrier layer located between the magnetic free layer and the magnetic reference layer; and
a synthetic antiferromagnetic structure, further comprising:
a first multilayer structure comprising a plurality of bi-layers of Pt and Co;
a second multi-layer structure comprising a plurality of bi-layers of Pt and Co; and
a non-magnetic anti-parallel exchange coupling layer located between the first multi-layer structure and the second multilayer structure;
wherein:
the second multi-layer structure is exchange coupled with the magnetic reference layer;
the first multi-layer structure has 7 Pt/Co bi-layers; and
the second multi-layer structure has 4 Pt/Co bi-layers.