Electronic structure and transport properties of pseudogap system Fe2VAl

The Heusler-type Fe2VAl compound exhibits a semiconductor-like behavior with the resistivity reaching 30 mu Omegam at 2 K. Recent band-structure calculations predict that Fe2VAl is a nonmagnetic semimetal with a sharp pseudogap at the Fermi level. The existence of a pseudogap is experimentally confirmed in optical conductivity spectra and is also supported by Hall-effect measurements. A substantial mass enhancement is deduced from electronic specific-heat measurements, reminiscent of a 3d heavy-fermion system. The unusual electron transport is mainly interpreted in terms of the effect of strong spin fluctuations in addition to the possession of a low carrier density. Since a small deviation fi om stoichiometry causes a large enhancement in the Seebeck coefficient, the pseudogap system Fe2VAl can be regarded as an intriguing candidate for thermoelectric applications.