Crystal orientation, order degree, and surface roughness of FePd-alloy film formed on MgO(001) substrate

To enhance the ordering with the c-axis perpendicular to the substrate surface, an application of in-plane lattice tension or out-of-plane lattice compression on the A1-FePd film seems useful, since the c/a ratio of bulk L10-FePd crystal is 0.97. In FePd/MgO heterostructure, the lattice of FePd film is considered to be effectively expanded along the in-plane direction through accommodation of the lattice misfit with respect to the MgO substrate (-9%). For practical applications, a wide range of film thicknesses from a few nm to several μm are required. The lattice strain and the c-axis orientation are considered to be influenced by the film thickness. In the present study, FePd films are prepared on MgO(001) substrates by varying the thickness from 1 to 500 nm. The c-axis orientation, the order degree, the surface roughness, and the magnetic property were systematically investigated.