Excellent reliability of CoFe-IrMn spin valves

The thermal reliability of spin valve films with a CoZrNb/NiFe/CoFe free layer and a CoFe/IrMn pinned layer was investigated. Stable properties; including an MR ratio of 7.5/spl sim/8%, an exchange bias of 400/spl sim/500 Oe in the pinned layer, an interlayer coupling of less than 10 Oe between the pinned and free layers, and soft magnetic properties of the free layer, were observed even after annealing for 100 hours at 270/spl deg/C. It was demonstrated that the IrMn/CoFe interface, as well as the CoFe/Cu interface, is extremely stable against interdiffusion. These films also showed an MR ratio of 5% and an exchange bias of 200 Oe even at 160/spl deg/C.