Off-stoichiometric effect on the transport and pseudogap characteristics of Fe2VGa

We report the investigations of transport and thermoelectric measurements on the Heusler compounds Fe2VGa1+x over the temperature range from 10 to 300 K. It is found that the electrical resistivity and Seebeck coefficient are very sensitive to the off-stoichiometry, while the thermal conductivity is relatively little affected with the composition change. With a removal of Ga content from the stoichiometric Fe2VGa, a sign change in the Seebeck coefficient accompanied by a broad minimum at around 130 K is observed. The latter feature can be interpreted as thermal excitation of carriers across band edges, in accord with band-structure calculations. Furthermore, an analysis of lattice thermal conductivity indicates that the off-stoichiometric effect on both electrical resistivity and Seebeck coefficient is not influenced by chemical disorder.