Experimental realization of a semiconducting full Heusler compound: Fe2TiSi

Single-phase films of the full Heusler compound Fe2TiSi have been prepared by magnetron sputtering. The compound is found to be a semiconductor with a gap of 0.4eV. The electrical resistivity has a logarithmic temperature dependence up to room temperature due to Kondo scattering of a dilute free electron gas off superparamagnetic impurities. The origin of the electron gas is extrinsic due to disorder or off-stoichiometry. Density functional theory calculations of the electronic structure are in excellent agreement with electron energy loss, optical, and x-ray absorption experiments. Fe2TiSi may find applications as a thermoelectric material.