Magnetic structures and out-of-plane magnetic anisotropy at the exchange bias interface: Co/FeMn

The magnetic structures and anisotropy at the compensated ferromagnetic/antiferromagnetic Co/FeMn interface are investigated by the highly precise first principles full-potential linearized augmented plane-wave method that incorporates intra-atomic noncollinear magnetism in order to understand the magnetic complexity involved in the spin-flop coupling and the presence of intra-atomic noncollinear magnetism. The self-consistent results predict that the Fe moments in the FeMn layer reorient away from their directions in bulk FeMn so as to be parallel to the Co moment direction-a reorientation that induces an out-of-plane magnetic anisotropy. These results appear to support and confirm recent experimental x-ray magnetic circular dichroism findings that rule out spin-flop coupling as the mechanism for exchange bias in this system.