Influence of Ga⁺ ion irradiation on the magnetisation reversal process and magnetoresistance in CoFe/Cu/CoFe/IrMn spin valves

Ga⁺ ion irradiation is performed on the surfaces of IrMn-based spin valves and the effects of ion irradiation on the magnetisation reversal process and magnetoresistance (MR) are investigated. The results show that the exchange bias field and magnetoresistance ratio of the spin valve decrease with the increase of ion dose. The width of the forward step between the free layer and the pinned layer becomes gradually smaller with the increase of ion dose whilst the recoil step tends to be narrower with ion dose increasing up to 6×10¹³ ions/cm² and the step disappears afterwards. Two peaks in the R--H curve are found to be asymmetric.