Surface electronic structure of the Fe3O4(100):: Evidence of a half-metal to metal transition -: art. no. 104436

In situ prepared Fe3O4(100) thin films were studied by means of scanning tunneling microscopy (STM) and spin-polarized photoelectron spectroscopy (SP-PES). The atomically resolved (root 2 x root 2)R45 degrees wavelike surface atomic structure observed by STM is explained based on density functional theory (DFT) and ab initio atomistic thermodynamics calculations as a laterally distorted surface layer containing octahedral iron and oxygen, referred to as a modified B layer. The work-function value of the Fe3O4(100) surface extracted from the cutoff of the photoelectron spectra is in good agreement with that predicted from DFT. On the Fe3O4(100) surface both the SP-PES measurements and the DFT results show a strong reduction of the spin polarization at the Fermi level (E-F) compared to the bulk density of states. The nature of the states in the majority band gap of the Fe3O4 surface layer is analyzed.