Weak magnetic moment on IrMn exchange bias pinning layers

Abstract

We present evidence from soft x-ray resonant magnetic scattering measurements at the Mn L3 edge for the existence of a small magnetic moment on the antiferromagnetic IrMn pinning layer in a NiFe/Cu/Co/IrMn spin valve structure. The variation of the signal in an applied magnetic field shows that the moment lies antiparallel to the Co moment. Changes in the Mn L3 edge signal as the Co moment is rotated into the hard direction are rapid and do not appear to be associated with thermal reordering of the antiferromagnetic domain structure.