Unusual electron transport in Heusler-type Fe2VAl compound

The electrical resistivity of D03-type (Fe1−xVx)3Al shows an anomalous temperature dependence characterized by a resistance maximum near the Curie point and a negative resistivity slope at higher temperatures up to 1000 K and above. In particular, the Heusler-type Fe2VAl compound is found to be in a marginally magnetic state and to exhibit a semiconductor-like behavior with the resistivity reaching 3000 μΩ cm at 2 K, in spite of the presence of a clear Fermi edge as revealed in valence-band photoemission spectra. A substantial mass enhancement deduced from electronic specific-heat measurements suggests that Fe2VAl is a possible candidate for a 3d heavy-fermion system. According to electronic structure calculations, Fe2VAl is a nonmagnetic semimetal with a narrow pseudogap at the Fermi level. The unusual electron transport is mainly interpreted in terms of the effect of strong spin fluctuations, in addition to the existence of very low carrier concentrations.