Growth evolution of γ′-Fe₄N films on GaN(0001) and their interfacial structure

We report the growth parameter dependence of structural and magnetic properties of γ′-Fe 4 N thin films on GaN(0001) grown by plasma-assisted molecular beam epitaxy, particularly focusing on their interfacial structure. Reflection high-energy electron diffraction (RHEED) and X-ray diffraction reveal that γ′-Fe 4 N(111) layers are grown at the interface, while the succeeding layers are preferentially oriented to (111) or (100) depending on the growth conditions. The RHEED observation during the interface formation and the cross-sectional transmission electron microscopy observation indicate that the γ′-Fe 4 N(111)/GaN interface is abrupt. On the basis of the present findings, we propose the structural model for the interface.