Magnetic order and spin-flop transition in Co-Re multilayers

Abstract

Polarized neutron reflectometry measurements were carried out on a thin-film Co-Re multilayer sample with Re thickness of 6 Å which is at the peak of the first oscillation of the magnetoresistance. Antiferromagnetic coupling between successive Co layers is observed at in-plane magnetic fields below 0.1 T. Towards the low field end of this regime, the axes of the antiferromagnetic domains are distributed relatively uniformly in the sample plane but at ∼0.1 T the moments flop perpendicular to the applied field. As the field is increased further, the Co moments are pulled into the field direction producing a partial ferromagnetic alignment. At 0.5 T, the highest field where the measurements have been made, the antiferromagnetic to ferromagnetic transition was found to be only ∼50% complete, indicating that the saturation field required for Co-Re system is much higher than that for Co-Cu multilayers of similar layer spacing.