Orientation and magnetic properties of FePt and CoPt films grown on MgO(1 1 0) single-crystal substrate by electron-beam coevaporation

We have studied the orientation and magnetic properties of FePt and CoPt films deposited by electron-beam co-evaporation on MgO(1 1 0) single-crystal substrates at substrate temperatures from 500 to 700 °C. We observed that long-range chemical ordering of the L1₀ structure occurred over the entire range of substrate temperatures in FePt films and at 600 °C and up in CoPt films. Growth of FePt and CoPt yielded epitaxial films with cube-on-cube orientation of the pseudo-cubic L1₀ lattice with respect to the cubic MgO. X-ray diffraction patterns and magnetization loops of the FePt and CoPt films revealed the existence of L1₀ domains with the tetragonal c axis inclined at 45° to the film plane, orientations (0 h h) and (h 0 h), as well as L1₀ domains with the tetragonal c axis in the plane of the film, orientation (h h 0). The FePt and CoPt films for which X-ray diffraction indicated tetragonal phase was present all exhibited hard magnetic properties with easy axis along the [0 0 1] substrate direction as well as large in-plane magnetocrystalline anisotropy.