Electrical transport, magnetic, and thermal properties of FeSi

We report measurements of the electrical conductivity, magnetoresistance, Hall effect, magnetic susceptibility, and specific heat, measured in different temperature ranges between 0.05 and 300 K, on a high-quality FeSi single crystal grown by vapour transport. The semiconductor-like temperature dependence of the resitivity of FeSi arises essentially from thermal activation of charge carriers across two different energy gaps. Several features suggest that s - d hybridization effects are important. At low temperatures some evidence of electron-electron interactions is found.