Resettable symmetric spin valve

Details Resettable symmetric spin valve Resettable symmetric spin valve

1997-05-13

1998-05-05

Tupper, Robert S.

Dynamic magnetic information storage or retrieval

General recording or reproducing

Specifics of biasing or erasing

360113, G11B 503, G11B 539

Patent

active

057483990

ABSTRACT:
A read sensor includes first and second symmetric spin valves with resettable magnetization directions. The first spin valve includes an antiferromagnetic layer, a ferromagnetic pinned layer, a non-magnetic conductor layer, then a ferromagnetic free layer. The ferromagnetic free layer is shared by the first and second spin valves. Upon the ferromagnetic free layer lies a non-magnetic conductor layer, then an inner ferromagnetic pinned layer and an outer ferromagnetic pinned layer sandwiching an exchange coupling layer. The exchange coupling layer exhibits sufficient exchange coupling with the sandwiching ferromagnetic pinned layers to pin these layers' magnetization directions in antiparallel directions. A second antiferromagnetic layer may be provided adjacent the second spin valve's outer ferromagnetic pinned layer. Directing a current pulse of suitable duration and magnitude through the conductors heats the antiferromagnetic layers beyond their blocking temperatures, providing the antiferromagnetic layers with a magnetization direction in accordance with the pulse's magnetic field. The newly established magnetization directions of the antiferromagnetic layers pins the first spin valve's ferromagnetic pinned layer as well as the second spin valve's outer ferromagnetic pinned layer. Furthermore, pinning of the second spin valve's outer ferromagnetic pinned layer establishes the magnetization direction of the second spin valve's inner ferromagnetic pinned layer due to the high exchange coupling between these two layers. Alternatively, the second antiferromagnetic layer may be omitted, with the second spin valve's inner and outer ferromagnetic pinned layers having uneven thicknesses to facilitate biasing of these layers using an external magnetic field.

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