Spin-valve Thermal Stability: Interdiffusion Versus Exchange Biasing

This paper focuses on the roles of exchange biasing and interdiffusion on the thermal stability of different spin-valve structures. The thermal stability of the exchange field was found to be an intrinsic property of the antiferromagnet structure-it is not significantly effected by roughness or the quality of crystalline texture in the spin-valve. Two routes for interdiffusion were observed: mixing at the Ta/NiFe interface and Mn interdiffusion into the pinned layer and beyond. Synthetic spin-valves showed improved thermal stability as the Ru layer acts as a barrier against Mn interdiffusion. Annealing the PtMn spin-valves significantly reduced interdiffusion, inducing a phase transition to the more stable PtMn fct state and passivating the Ta/NiFe intermixing.