Thin Mn germanide films studied by XPS, STM, and XMCD

Thin Mn germanide films with nanoscale thicknesses on Ge(111) have been studied by low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), core-level spectroscopy (CLS), and x-ray magnetic circular dichroism. The 260 [degrees]C annealing of 16 monolayers of Mn deposited on Ge(111)c(2 x 8) resulted in a uniform film with intense threefold split [radical]3 x [radical]3 LEED spots and Moire patterns in the STM images. This ultrathin film shows a clear ferromagnetism with a Curie temperature of ~250 K. High-resolution Ge 3d CLS spectra were recorded with photon energies between 50 and 90 eV at normal and 60[degrees] emission angle. To achieve a consistent fit over the energy and angular range three components were used in the line-shape analysis. The low temperature (260 [degrees]C) annealed film shows significant differences in terms of electronic structure and magnetism in contrast to the high temperature (330 [degrees]C or above) annealed ones. Our results indicate that the annealing temperature and the Mn coverage play important roles in the formation of a thin magnetic Mn germanide film.