Surface and bulk electronic structures of Heusler-type Fe2VAl

Abstract

Surface and bulk electronic structures of Heusler-type (L21 type) Fe2VAl have been investigated by photoelectron spectroscopy, in particular, for the valence band and V 2p core level regions, in order to elucidate the changes in the valence band electronic structures for the surface and bulk regions. In the valence band spectrum, the intensity at the Fermi level EF is increased for the surface-sensitive low photon energy excitation in comparison to the bulk-sensitive high photon energy excitation. It is also found that the intensity around a binding energy of 0.4eV is enhanced for large photoelectron takeoff angles for the bulk-sensitive photoelectron spectrum. The V 2p core level spectrum shows a surface-derived shoulder structure on the low binding energy side of the main feature, which suggests that the valence electron concentration around V may be large in the surface layers in comparison to the bulk. These facts suggest that a pseudogap is formed around EF in the bulk electronic structure, as predicted by band calculations, and that it is destroyed in the surface layers by the V 3d states as well as the Fe 3d states emerging in midpseudogap of the bulk electronic structure.