Partial magnetization reversal using laser annealing in patterned NiFe/FeMn film

We have studied local magnetization reversal by laser annealing in exchange biased NiFe/FeMn bilayer. Local magnetization reversal was performed by using the Nd:YAG laser under external magnetic field. When the laser illuminated the patterned film with the power of above 300 mW during 15 min, a magnetoresistance (MR) curve with symmetric peaks at the opposite field was obtained due to the local reversal of exchange biasing. A similar result was observed in NiFe/FeMn/NiFe trilayer. As the exposed area expanded, the intensity of opposite MR peak increased. The direction of exchange anisotropy in the partially reversed region can be restored by local laser annealing under alternating magnetic field, even if its MR peak was reduced by the damage and interdiffusion. The magnetic new domain structures of the partially reversed region was generated by laser annealing near the exposed area.