Introduction of VN underlayer and caplayer for preparation of Mn4N(001) single-crystal thin film with perpendicular magnetic anisotropy

A Mn4N thin film is prepared on MgO(001) single-crystal substrate by introducing VN underlayer and caplayer which are respectively expected to inhibit the oxidation from substrate and surface. The thin film is prepared by ultra-high vacuum radio-frequency magnetron sputtering. The growth, the structure, and the magnetic properties are investigated. A fully epitaxial VN/Mn4N/VN film with sharp interfaces is formed on the substrate. The Mn4N film has low out-of-plane and in-plane orientation dispersions of about 1° and high N site order degree of 0.88. The lattice of Mn4N film is slightly deformed along the perpendicular direction (c/a = 0.9872) possibly due to accommodation of the lattice mismatch at Mn4N/VN interfaces. The film shows a low saturation magnetization of 85 kA/m (85 emu/cm3) and a strong perpendicular magnetic anisotropy. The present study has shown that introduction of VN underlayer and caplayer is useful for preparation of well-defined Mn4N thin films with perpendicular magnetic anisotropy.