Patterned ferromagnetic and exchange biased nanostructures

Exchange bias effects have been systematically investigated in Co (25 nm)/CoO (5 nm)/Cu (2 nm) nanoring arrays and Cu (10 nm)/NiFe (30 nm)/IrMn (30 nm)/Cu (2 nm) nanoscale antidot arrays. For the nanorings, the magnetization reversal mechanism and magnitude of exchange bias field H_E is strongly dependent on the strength and orientation of the cooling field relative to the major axis of the nanorings. The antidot arrays exhibit asymmetric hysteresis loops and show larger He values as compared to the continuous film. This is attributed to reduced interactions in the NiFe layer and constraints imposed on the IrMn domain size by the antidots.