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

Annealing time effect on the magnetotransport properties was investigated f or Si/alumina/Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta samples having different PtMn th ickness (10-30 nm). Post-deposition heat treatment was performed using a va cuum furnace with 3 kOe, field at 270 degreesC up to 35 h. The thermally ac tivated atoms diffused to other layers through grain boundaries during the heat treatment with longer annealing hours resulting in deteriorating Delta R/R. This effect is more profound in films with thicker PtMn layers where i nterface became rougher after annealing. (C) 2001 Elsevier Science B.V. All rights reserved.