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Temperature dependence of giant magnetoresistance properties of NiMn pinned spin valves

1998; American Institute of Physics; Volume: 83; Issue: 11 Linguagem: Inglês

10.1063/1.367639

1520-8850

Sining Mao, Muhamad Amin, Ed Murdock,

Metal and Thin Film Mechanics

The giant magnetoresistance response of NiMn pinned spin valves was studied at elevated temperature. Top spin valve films were made by ion beam sputtering and thermally treated to induce the strong unidirectional pinning field in the pinned layer. Both δR and δR/R decrease linearly with temperature. The sheet resistance of the spin valves also increases linearly with temperature. The exchange coupling between pinned layer and free layer decreases slightly and the coercivity of the free layer increases slightly. The temperature dependence of the exchange pinning field is unique in NiMn spin valves. The pinning field has a weakly increasing temperature dependence up to 200 °C, then decreases to zero at the blocking temperature of 380 °C. Samples with different thickness NiMn layers show different temperature dependencies. However, the blocking temperature is unchanged. The pinning fields of NiMn, FeMn, IrMn, and NiO spin valves were also measured up to 200 °C; NiMn pinned spin valves show the least dependence of pinning field at elevated temperatures.