Counterbalanced-switch MRAM
A magnetic memory cell is provided. The cell comprises first and second free layers; and an intermediate layer separating the first and second free layers, wherein the first and second free layers are magnetostatically coupled.
1. A method for reducing current required to write to a magnetic storage layer of a magnetic memory cell, the method comprising:
splitting the magnetic storage layer for the magnetic memory cell into first and second free magnetic layers; and
magnetostatically coupling the first and second free magnetic layers by separating the layers by a metal line such that a magnetization direction of the first free magnetic layer is opposite a magnetization direction of the second free magnetic layer.
2. The method of claim 1 , further comprising forming the first and second free magnetic layers such that each comprises a plurality of sub-layers.
3. The method of claim 1 , further comprising configuring the metal line and another metal line to each carry a respective write current used to collectively energize the first and second free magnetic layers during write operations.
4. The method of claim 3 , further comprising reducing the current required by the other metal line to write to the magnetic storage layer even further by forming the other metal line between the second free magnetic layer and a third free magnetic layer.
5. The method of claim 3 , further comprising reducing the current required by the other metal line to write to the magnetic storage layer even further by placing a third free magnetic layer on the other metal line and opposite the second free magnetic layer.
6. The method of claim 1 , further comprising forming the first and second free magnetic layers to have different materials, shapes, and dimensions.
7. The method of claim 1 , further comprising introducing another metal line below the magnetic memory cell, without any lateral offset from the magnetic memory cell.
8. The method of claim 7 , further comprising defining the write current through the first metal layer such that magnetization directions of the first and second free magnetic layers are not switched without a contribution from a write current of the other metal line for the magnetic memory cell.
9. The method of claim 1 , further comprising covering a side wall of the metal line with magnetic material.
10. A magnetic memory cell, comprising:
a first, second, and third metal line;
a magnetic storage element including a first free magnetic layer coupled between the second and third metal lines; and
a second free magnetic layer positioned between the first and second metal lines, wherein:
the first and second free magnetic layers are magnetostatically coupled such that a magnetization direction of the first free magnetic layer is opposite a magnetization direction of the second free magnetic layer; and
the first and second metal lines are configured to create a switching field in response to respective write currents that is sufficient to switch the magnetization directions of the first and second free magnetic layers.
11. The magnetic memory cell of claim 10 , wherein the first and second free layers each comprise a plurality of sub-layers.
12. The magnetic memory cell of claim 11 , further comprising a third free magnetic layer, wherein the first metal line is positioned between the first and third free magnetic layers.
13. The magnetic memory cell of claim 12 , wherein the third free magnetic layer sits on the first metal line.
14. The magnetic memory cell of claim 11 , wherein the first and second free magnetic layers have different materials, shapes, and dimensions.
15. The magnetic memory cell of claim 11 , wherein the third metal line is not laterally offset from the magnetic storage element.
16. The magnetic memory cell of claim 11 , wherein the magnetic storage element further comprises:
a fixed magnetic layer; and
a tunneling layer between the fixed magnetic layer and the first free magnetic layer.
17. The magnetic memory cell of claim 11 , further comprising a dielectric layer between the first metal line and the second free magnetic layer.
18. The magnetic memory cell of claim 11 , wherein a layer of magnetic material covers side walls of the first, second, and third metal lines.
19. The magnetic memory cell of claim 11 , wherein:
the first metal line is a bit line;
the second metal line is a word line; and
the third metal line is a read line.
20. The magnetic memory cell of claim 11 , wherein:
the first metal line is a word line;
the second metal line is a bit line; and
the third metal line is a read line.