Influence of Ga+ ion irradiation on magnetoresistance and exchange bias of IrMn/CoFe/Cu/CoFe/NiFe spin valve

Abstract

The spin valve with the structure of IrMn/CoFe/Cu/CoFe/NiFe has been patterned to be a wire with four current-voltage probes. The detailed study of the influence of 30 KeV focused Ga+ ion beam irradiation on the magnetoresistance and exchange bias on the patterned sample has been carried out. With an increase in the ion dose, magnetoresistance and exchange bias have been found to be decreasing, and resistance has been found to be increasing. At low doses (≤1.05 × 1015 ions/cm2), the alternation in resistance is mainly attributed to atomic mixing in the interfacial regions induced by Ga+ ion irradiation. However, at high doses (≥3.51 × 1015 ions/cm2), the bulk defects generated by Ga+ ion irradiation have a significant effect on the increase of resistance. At the dose of 3.51 × 1015 ions/cm2 both GMR and AMR behaviors have been observed. © 2001 Published by Elsevier Science Ltd.