Electronic structure of possible 3d 'heavy-fermion' compound Fe2VAl

Recent transport, specific heat and magnetization measurements indicated that the Heusler-type Fe2VAl compound is a candidate for a 3d heavy-fermion system. As a first step towards a detailed theoretical understanding of the observed anomalous electronic properties of this compound, we have performed first principles electronic structure and total energy calculations for Fe3Al and Fe2VAl. The calculated lattice constants and magnetic moments are in good agreement with experiments. Remarkably, we find that, unlike Fe3Al, Heusler-type Fe2VAl is a nonmagnetic semimetal with a narrow pseudogap at the Fermi level. Furthermore, our calculations suggest that the observed large enhancement of electronic specific heat coefficient is largely caused by the mechanisms such as spin-fluctuations rather than electron-phonon coupling in Fe2VAl. The relations between the existence of the Fermi surface and negative temperature dependence of the low-temperature electrical resistivity in Fe2VAl are discussed and further experimental and theoretical work is suggested.