Abstract
The influence of ion dosage on exchange field and giant magnetoresistance (GMR) of irradiated PTMN-based spin valves was discussed. The effects of C ion dosage were investigated on phase transformation of PtMn and on GMR of PtMn-based spin valves. It was found that by choosing proper dosage of C ion irradiation on PtMn-based spin valves, we can significantly enhance exchange field with a relatively low annealing temperature and obtain reasonably high MR ratio.