Microstructural evolution in PtMn-based spin-valves induced by heat treatment

Annealing time effect on the magnetotransport properties was investigated for Si/alumina/Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta samples having different PtMn thickness (10-30 nm). Post-deposition heat treatment was performed using a vacuum furnace with 3 kOe field at 270 deg. C up to 35 h. The thermally activated atoms diffused to other layers through grain boundaries during the heat treatment with longer annealing hours resulting in deteriorating ΔR/R. This effect is more profound in films with thicker PtMn layers where interface became rougher after annealing