Epitaxial growth and magnetic properties of Fe4−xMnxN thin films grown on MgO(0 0 1) substrates by molecular beam epitaxy

Epitaxial Fe4−xMnxN (x = 0, 1, 2, 3, and 4) thin films were successfully grown on MgO(0 0 1) single-crystal substrates by molecular beam epitaxy, and their crystalline qualities and magnetic properties were investigated. It was found that the lattice constants of Fe4−xMnxN obtained from X-ray diffraction measurement increased with the Mn content. The ratio of the perpendicular lattice constant c to the in-plane lattice constant a of Fe4−xMnxN was found to be about 0.99 at x⩾2. The magnetic properties evaluated using a vibrating sample magnetometer at room temperature revealed that all of the Fe4−xMnxN films exhibited ferromagnetic behavior regardless of the value of x. In addition, the saturation magnetization decreased non-linearly as the Mn content increased. Finally, FeMn3N and Mn4N exhibited perpendicular anisotropy and their uniaxial magnetic anisotropy energies were 2.2 × 105 and 7.5 × 105 erg/cm3, respectively.