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US 7,570,510 B2Granted
Multi-bit spin memory
AssigneeSeagate Technology International
InventorMark B. Johnson
Life of this patent
Estimating the term…
Abstract
A multi-state spin based memory cell uses a pair of ferromagnetic layers. A first ferromagnetic layer can be set to any known state k from a set of n different states by adjusting a magnetic orientation of such layer. The relationship of the first ferromagnetic layer and a second magnetic layer can thus correspond to a value of a data item in a non-volatile multi-bit memory cell.
Claims20
A spin polarized electron current device comprising:
- a first ferromagnetic layer having a first coercivity and a variable first magnetization state;
- wherein said variable first magnetization state can be set to one of n different values, where n>2;
- a second ferromagnetic layer having a second coercivity larger than said first coercivity and a second magnetization state;
- wherein an impedance of the device to a spin polarized current varies in accordance with a relationship between said variable first magnetization state of said first ferromagnetic layer and said second magnetization state of said second ferromagnetic layer.
1 more element
A magnetic field sensor comprising:
- a first ferromagnetic region having a first fixed magnetization state;
- a second ferromagnetic region coupled to said first ferromagnetic region, and having a second coercivity smaller than said first coercivity and adapted to be responsive to a variable magnetic field;
- said second ferromagnetic region having a second variable magnetization state that can be set by a write signal to any one of a set of n different values, where n>2;
- wherein the magnetic field sensor is adapted to conduct a spin polarized current with a current value corresponding to said second variable magnetization state of said second ferromagnetic region, such that the sensor can detect which one of said n different values is set in said second variable magnetization state.
1 more element
A multi-bit memory cell comprising:
- a non-volatile storage layer including a first ferromagnetic layer adapted to store up to n different logical values for the multi-state memory cell, including a logical value k for the multi-state memory cell, where 2<k<=n;
- a second ferromagnetic layer coupled to said first ferromagnetic layer;
- wherein said multi-bit memory cell is adapted to conduct a spin polarized current whose value varies in accordance with a relationship between a first orientation of said first ferromagnetic layer and a second orientation of said second ferromagnetic layer and corresponds to said logical value k.
Dependencies are inferred from the claim text.