Temperature dependent magnetization reversal of exchange biased magnetic vortices in IrMn/Fe microcaps

Abstract

The authors investigated the magnetization reversal of vortex structures in Fe as well as in IrMn/Fe magnetic caps at elevated temperatures up to 450 K. The caps were formed by film deposition onto dense arrays of self-assembled silica particles of 900 nm diameter. In the investigated temperature range, the magnetization reversal in Fe caps evolves via nucleation and annihilation of magnetic vortices. However, in exchange coupled IrMn/Fe caps, the magnetic vortex at zero magnetic field vanishes as the temperature approaches the blocking temperature of IrMn accompanied by an increase in coercivity. Further increase in temperature, approaching the N eel temperature of IrMn, results in a reduction of coercivity as well as remanence indicating the restabilization of a vortex state.