Magnetization reversal in exchange biased antidot arrays

Abstract

A systematic study of the exchange bias effects in arrays of Cu (10nm)∕NiFe (30nm)∕IrMn (tIrMn)∕Cu (2nm) nanoscale antidot arrays prepared by deep ultraviolet lithography is presented. The magnetic properties of the antidot arrays are compared to that of a continuous film of identical composition. We observed that the antidots demonstrate higher coercivity and exchange bias fields. This enhancement in the exchange bias field, and the relative evolution of exchange bias field with the IrMn layer thickness tIrMn for both the antidot array and the continuous film, is attributed to the physical limitations imposed on the IrMn domain size by the reduced lateral dimensions of the antidots. Magnetoresistance measurements further corroborate the results obtained from the hysteresis loops.