Electronic structure and transport properties of pseudogap system Fe2 VAl

Abstract

The Heusler-type Fe2 VAl compound exhibits a semiconductor-like behavior with the resistivity reaching 30 μΩm at 2 K. Recent band-structure calculations predict that Fe2 VAl 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 from stoichiometry causes a large enhancement in the Seebeck coefficient, the pseudogap system Fe2 VAl can be regarded as an intriguing candidate for thermoelectric applications.