Electronic band structure of epitaxial √3x√3R30°ε-FeSi(111)/Si(111)

The electronic band structure of root 3 x root 3R30 degrees epsilon-FeSi(111) epitaxially grown on Si(111) has been probed by angle-resolved polarization-sensitive ultraviolet photoemission in the energy range 8 eV less than or equal to hv less than or equal to 30 eV. The bands were mapped along the Gamma R direction of the Brillouin zone for different detection geometries. A comparison with theoretical calculations reveals a good agreement of the overall features at room temperature. A sharp peak close to the Fermi energy was observed. Its origin is discussed taking into account both conventional and Kondo-insulator models currently considered to explain the properties of epsilon-FeSi.