Interfacial and bulk order in polycrystalline exchange bias systems

Abstract

A study of the effect of the setting conditions on the two coercive fields HC1 and HC2 in an exchange bias system is presented. The study was performed on a polycrystalline thin film sample of composition Si/Cu(5 nm)/IrMn(10 nm)/CoFe(2 nm)/Ta(5 nm) with a median blocking temperature ⟨TB⟩=240 K. An experiment analogous to a thermoremanence experiment, where order is quenched in by field cooling, is compared to a setting field experiment at constant temperature. These processes can be used to probe the order of the interfacial spin clusters and the bulk of the antiferromagnet. HC1 and HC2 follow different setting temperature dependences, indicating that different mechanisms are dominant in the two branches of the loop.