Exchange-bias effect in Fe/Cr(211) double superlattice structures

Shifted hysteresis loops characteristic of the exchange-bias effect between a ferromagnet (F) and an antiferromagnet (AF) are demonstrated in "double- superlattice" structures. Utilizing the well-established oscillatory interl ayer exchange coupling in Fe/Cr, we have constructed [Fe/Cr](AF)/Cr/[Fe/Cr] (F) double superlattices where Fe/Cr superlattices with appropriate Cr-spac er thickness represent the F and the AF. The double superlattices are (211) -oriented epitaxial films sputter grown on single-crystal MgO(110) substrat es. The AF/F interface is coherent compared to conventional exchange-bias i nterfaces consisting of dissimilar AF and F phases. Magnetization results s how that AF/F exchange coupling affects the nucleation of reverse magnetic domains, and that the magnitude of the exchange-bias field is given directl y by the classic formula for collinear spin structures. The collinear spin distribution is confirmed by polarized neutron reflectivity.