Scanning tunneling microscopy study of surface structure and magnetism of Fe thin films grown on MgO (001)

Substrate preparation procedure dependence of the growth morphology and mag netic properties of 25 ML bcc-Fe(001) thin films epitaxially grown on MgO(0 01) substrates in a wide range of growth temperature was investigated by me ans of scanning tunneling microscopy (STM) and superconducting quantum inte rference device(SQUID). The growth morphology of Fe thin films was uniform both on a polished and on an annealed substrate, but nonuniform on a cleave d substrate. It was very difficult to obtain a flat Fe thin film on the cle aved substrate, and the film became discontinuous gt or above a growth temp erature of 493 K. At a growth temperature of 550 K, atomically defined terr aces of Fe thin films were formed on the annealed substrate but. were not f ormed on the polished substrate. A continuous film grown on the annealed su bstrate at a temperature of 593 K has a less magnetic anisotropy. The other continuous films have low coercivity of about 8 Oe and a biaxial magnetic anisotropy. The dependency of the growth morphology and magnetic properties of Fe thin films upon substrate preparation procedures concerning the pres ence of step-terraces on the substrate surface is discussed.