Annealing cycle number dependence of magnetoresistance in alloy NiMn-pinned spin valves

Abstract NiMn-pinned spin valve films with the stacks of Glass/NiFe/Co/Cu/Co/NiFe/NiMn/Ta were made by DC magnetron sputtering and the annealing cycle number dependence of magnetoresistance in the films was investigated. By optimizing the process of deposition and post thermal annealing cycle, we obtained the NiMn-spin valve films with MR ratio of 2.5%, exchange coupling field of 620 Oe, and coercivity of 250 Oe for the pinned layer. The exchange coupling field maintained its strength in operation up to 175°C and decreased monotonically to zero at 380°C.