Exchange anisotropy of MBE grown Mn1−Pt /NiFe bilayers with (0 0 1) orientation

Abstract Exchange anisotropy was investigated for Mn 1− x Pt x ( x =0.06–0.40)/NiFe epitaxial bilayers with (0 0 1) orientation grown applying a magnetic field along either [1 0 0] or [1 1 0]. The bilayers exhibited a large exchange bias field without heat treatment. The easy direction of the unidirectional anisotropy was independent of the applied field direction and always parallel to [1 1 0] direction of the crystal axis. The magnetic anisotropy torque curves contain strong 4-fold symmetry component whose amplitude is much larger than that of NiFe single layers.