Electronic, magnetic and transport properties of (Fe1-xVx)3Al alloys

Abstract

We report electronic, magnetic and transport properties of (Fe_1-x V_x )₃ Al alloys with x = 0 - 0.38 and analyse the results on the basis of the measured electronic specific-heat coefficient, the Debye temperature and the magnetic stiffness constant. As the V composition increases, the electrical resistivity increases rapidly at low temperatures and the magnetization decreases significantly in parallel with a sharp reduction in the Curie temperature. In particular, the Heusler-type Fe₂ VAl compound (x = 0.33) is found to be in a marginally magnetic state and to exhibit a semiconductor-like behaviour with the resistivity reaching 3000 µ cm at 2 K. Low-temperature specific heat studies demonstrate a substantial decrease in carrier concentration with the V substitution, being consistent with recent band calculations, which predict that Fe₂ VAl is a nonmagnetic semimetal with a sharp pseudogap at the Fermi level. A large mass enhancement deduced from the electronic specific-heat measurements suggests that Fe₂ VAl is a possible candidate for a 3d heavy-fermion system. The unusual electron transport is mainly attributed to the effect of strong spin fluctuations, in addition to the existence of very low carrier concentrations.