Three-dimensional (3D) magnetic memory devices comprising a magnetic tunnel junction (MTJ) having a metallic buffer layer
View Patent ↗A magnetic memory device comprises a cylindrical core and a plurality of layers surrounding the core. The plurality of layers include a metallic buffer layer, a ferromagnetic storage layer, a barrier layer, and a ferromagnetic reference layer. The cylindrical core, the metallic buffer layer, the ferromagnetic storage layer, the barrier layer, and the ferromagnetic reference layer collectively form a magnetic tunnel junction. A magnetization of the ferromagnetic layer storage parallels an interface between the metallic buffer layer and ferromagnetic storage layer.
1. A magnetic memory device comprising:
a cylindrical core;
a plurality of layers surrounding the core, including:
a metallic buffer layer;
a ferromagnetic storage layer;
a barrier layer; and
a ferromagnetic reference layer;
wherein:
the metallic buffer layer is positioned between the barrier layer and the ferromagnetic storage layer;
the cylindrical core, the metallic buffer layer, the ferromagnetic storage layer, the barrier layer, and the ferromagnetic reference layer collectively form a magnetic tunnel junction; and
a magnetization of the ferromagnetic storage layer parallels an interface between the metallic buffer layer and ferromagnetic storage layer.
2. The magnetic memory device of claim 1 , wherein:
the metallic buffer layer reduces a magnetic anisotropy contribution resulting from the interface between the metallic buffer layer and the ferromagnetic storage layer; and
the magnetic anisotropy is in a direction that is perpendicular to the magnetization of the ferromagnetic storage layer.
3. The magnetic memory device of claim 1 , wherein the cylindrical core is a non-magnetic metal.
4. The magnetic memory device of claim 1 , wherein:
the ferromagnetic reference layer surrounds the cylindrical core;
the barrier layer surrounds the ferromagnetic reference layer;
the metallic buffer layer surrounds the barrier layer; and
the ferromagnetic storage layer surrounds the metallic buffer layer.
5. The magnetic memory device of claim 1 , wherein:
when the metallic buffer layer is a first material, the ferromagnetic storage layer has a first thermal stability; and
when the metallic buffer layer is a second material distinct from the first material, the ferromagnetic storage layer has a second thermal stability greater than the first thermal stability.
6. The magnetic memory device of claim 5 , wherein the second material is selected from the group consisting of: aluminum, magnesium, ruthenium, and rhenium.
7. The magnetic memory device of claim 1 , wherein:
the ferromagnetic storage layer has a first set of characteristics; and
the ferromagnetic reference layer has a second set of characteristics that at least partially differ from the first set of characteristics.
8. The magnetic memory device of claim 7 , wherein a magnetic ground state of the ferromagnetic storage and reference layers is based, at least in part, on characteristics of the ferromagnetic storage and reference layers, respectively.
9. The magnetic memory device of claim 8 , wherein the characteristics include: (i) respective thicknesses of the ferromagnetic storage and reference layers and (ii) respective heights of the ferromagnetic storage and reference layers.
10. The magnetic memory device of claim 8 , wherein the magnetic ground state is one of: an out-of-plane ground state or a vortex ground state.
11. The magnetic memory device of claim 8 , wherein the magnetic ground state is further based on characteristics of the cylindrical core.
12. The magnetic memory device of claim 11 , wherein the characteristics of the cylindrical core include: (i) a radius of the cylindrical core and (ii) a height of the cylindrical core.