AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP15
Surface and Bulk Electronic Structures of Heusler-type Fe@sub 2@VAl

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Surface Science Poster Session
Presenter: M. Miyzaki, Nagoya University, Japan
Authors: M. Miyzaki, Nagoya University, Japan
K. Soda, Nagoya University, Japan
S. Yagi, Nagoya University, Japan
M. Kato, Nagoya University, Japan
T. Takeuchi, Nagoya University, Japan
U. Mizutani, Toyota Physical and Chemical Research Institute, Japan
Y. Nishino, Nagoya Institute of Technology, Japan
Correspondent: Click to Email
Surface and bulk electronic structures of Heusler-type Fe@sub 2@Al have been studied by both surface- and bulk-sensitive 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 and to clarify the mechanisms of its unusual transport properties@footnote 1@ and of the large enhancement of its thermoelectric power on a small deviation in the chemical composition.@footnote 2@ The valence band spectrum reveals fairly large intensity at the Fermi level E@sub F@ for the surface-sensitive low photon energy excitation but considerably small E@sub F@ intensity for the bulk-sensitive high photon energy excitation. This intensity reduction implies that a pseudogap is formed around E@sub F@ in the bulk electronic structure, as predicted by band calculations.@footnote 2@ The intensity between the binding energy of 0.4 eV and E@sub F@ is relatively increased for the large photoelectron takeoff angle (measured from the surface normal). These facts indicate that the pseudogap is destroyed in the surface layers. The V 2p core level spectrum shows a surface-derived satellite structure in the low binding energy side of the main bulk band. This suggests that the valence electron concentration around V may be large in the surface region in comparison to the bulk. We will discuss the surface and bulk electronic structures with use of a DV-X@alpha@ local electronic structure calculation. @FootnoteText@ @footnote 1@ Y. Nishino et al., Phys. Rev. B71, 094425 (2005).@footnote 2@ Y. Nishino, Materials Trans. 42, 902 (2001).