Ferrimagnetic-ferromagnetic phase transition in Au-doped Mn4N epitaxial films confirmed by x-ray magnetic circular dichroism

The antiperovskite ferrimagnet Mn4N has perpendicular magnetic anisotropy and small spontaneous magnetization, both of which are favorable properties for current induced domain wall motion. Previously we have investigated the magnetic structure of 3d-element-doped Mn4N thin films and demonstrated ultrafast domain wall velocities reaching 3000 m s−1 in the vicinity of the magnetic compensation composition of Ni-doped Mn4N at the current density of j = 1.2 × 1012 A m−2 at room temperature (RT). In this study, we investigate the effect of Au doping on the magnetic structure of Mn4N films, and present a composition ratio-dependent sign reversal of the anomalous Hall effect at RT. X-ray magnetic circular dichroism measurement revealed that the magnetic moment of the face-centered Mn atoms of Mn4−xAuxN reversed between x = 0.1 and 0.2, and became parallel to that of the corner-site Mn atoms for x = 0.2 and 0.3. This result suggests that the ferrimagnetic-ferromagnetic phase transition occurred in Au-doped Mn4N epitaxial films as in the In-doped Mn4N epitaxial films.