Optimization of exchange-biased Heusler alloys

Abstract

We report on a systematic study of ferromagnetic (F) Co2FeSi Heusler alloy films exchange-biased by antiferromagnetic (AF) IrMn. We have found that IrMn can produce an exchange-bias in the Heusler alloy with a loop shift of up to 200 Oe after optimized annealing. We also report on the effect of the insertion of a thin (<2 nm) layer of Mn at the interface. We have found that the insertion of a 0.5 nm thick Mn layer can increase the exchange-bias by a factor of two. Excessive annealing is found to decrease the exchange-bias dramatically and to disappear eventually. We believe this is due to Mn diffusion from the interface.