Structure optimization and thermal annealing effect of IrMn-based bottom spin valves

IrMn-based bottom spin valves fabricated by DC magnetron sputtering method were investigated. An optimized thickness (20/spl Aring/) of buffer layer was proposed for the bottom pinned structure: Ta(41/spl Aring/)/buffer layer/IrMn(82/spl Aring/)/CoFe(28/spl Aring/)/Cu(19/spl Aring/)/CoFe(10/spl Aring/)/NiFe( 45/spl Aring/)/Ta(38/spl Aring/); where buffer layer could be NiFe or Cu. With the optimized structure, high MR ratio (>8.5%) low coercivity (<0.8Oe); and high exchange bias field (>800Oe) were obtained. The thermal annealing effect on the GMR properties in bottom pinned structure was also studied. These simple bottom spin valves could be the promising robust giant magnetoresistance sensors for the automotive and industrial applications.