Electronic structure of Heusler-type Fe2V1+xAl1−x thermoelectric materials

We have investigated the electronic structure of the off-stoichiometric Fe2V1+xAl1−x alloys by high-resolution synchrotron radiation photoelectron spectroscopy (SR-PES) measurements in order to clarify the origin of the improvement in their thermoelectric properties. SR-PES results show that, for the Al-rich (hole-doping: x < 0) case, the change of the electronic structure can be explained by the rigid band model, while, for the V-rich (electron-doping: x > 0) case, the electronic structure is modified and the pseudo-gap widens with increasing V/Al substitution. The stability of the Heusler-type crystal structure and the modification of the electronic structure due to strongly correlated effects are possible factors contributing to the improvement in the thermoelectric properties of the n-type off-stoichiometric Fe2V1+xAl1−x alloys.