Method and system for providing a magnetic memory utilizing a shift register

A method for programming a magnetic memory, the magnetic memory including a plurality of magnetic memory elements corresponding to a plurality of magnetic memory cells, each of the plurality of magnetic memory elements including a pinned layer, a free layer, and a nonmagnetic spacer layer residing between the pinned layer and the free layer, each of the plurality of magnetic memory elements being configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic memory element of the plurality of magnetic memory elements, the method comprising:

• driving a shift current through at least one shift register corresponding to the plurality of magnetic memory elements, each of the at least one shift register including a plurality of domains separated by a plurality of domain walls, a domain of the plurality of domains being antiparallel to an adjoining domain, the at least one shift register being configured such that an equilibrium state aligns a portion of the plurality of domains with the plurality of magnetic memory elements, the at least one shift register being configured such that each of the plurality of domain walls is shifted to a location of an adjoining domain wall when the shift current is passed through the at least one shift register in a direction along adjoining domains such that each of the plurality of magnetic memory elements is in a dual state with the portion of plurality of domains;
• and
• driving the write current through at least one of the plurality of magnetic memory elements being written.

A method for programming a magnetic memory, the magnetic memory including a plurality of magnetic memory elements corresponding to a plurality of magnetic memory cells, each of the plurality of magnetic memory elements including a pinned layer, a free layer, and a nonmagnetic spacer layer residing between the pinned layer and the free layer, each of the plurality of magnetic memory elements being configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic memory element of the plurality of magnetic memory elements, the method comprising:

• driving the write current through at least a portion of at least one shift register corresponding to the plurality of magnetic memory elements and through at least one of the plurality of magnetic memory elements being written, each of the at least one shift register including a plurality of domains separated by a plurality of domain walls, a domain of the plurality of domains being antiparallel to an adjoining domain, the at least one shift register being configured such that an equilibrium state aligns a portion of the plurality of domains with the plurality of magnetic memory elements, the at least one shift register being configured such that each of the plurality of domain walls is shifted to a location of an adjoining domain wall when the write current is passed through the at least one shift register in a direction along adjoining domains such that each of the plurality of magnetic memory elements is in a dual state with the portion of plurality of domains.

A method for initializing a magnetic memory, the magnetic memory including a plurality of magnetic memory elements corresponding to a plurality of magnetic memory cells, each of the plurality of magnetic memory elements including a pinned layer, a free layer, and a nonmagnetic spacer layer residing between the pinned layer and the free layer, each of the plurality of magnetic memory elements being configured such that the free layer is switchable between a plurality of stable magnetic states when a write current is passed through the magnetic memory element of the plurality of magnetic memory elements, the method comprising:

• applying a magnetic field in a perpendicular direction to at least a portion of the plurality of magnetic memory elements and at least one shift register corresponding to the plurality of magnetic memory elements, each of the at least one shift register including a plurality of domains separated by a plurality of domain walls, a domain of the plurality of domains being antiparallel to an adjoining domain, the at least one shift register being configured such that an equilibrium state aligns a portion of the plurality of domains with the plurality of magnetic memory elements, the at least one shift register being configured such that each of the plurality of domain walls is shifted to a location of an adjoining domain wall when a shift current is passed through the at least one shift register in a direction along adjoining domains;
• wherein at least the free layer and the pinned layer provide a magnetostatic field antiparallel to the magnetic field at an additional portion of the plurality of domains between the plurality of magnetic memory elements such that each of the portion of the plurality of domains alternate with a non-aligned domain of the plurality of domains, the non-aligned domain residing between magnetic memory elements.