Compensation effects in a correlated insulator Fe1-xNixSi

Transport properties of Nickel (Ni) substituted FeSi are investigated. X-ray diffraction measurement shows that the samples are in single phase with Fe successfully being replaced by Ni. Thermo Electric Power (TEP) at low temperatures is dramatic in FeSi that show a systematic reduction by the incorporation of Nickel. Even though the resistivity down to 2K shows a semiconducting behavior, estimation of energy gap has been an ambiguous one. The effects of TEP are dramatic in the sense that it shows the compensation effects in a more clear fashion. A two band model incorporating a metallic and activated conduction resolves the issues like band gap cleaning at low substitution that eventually introduces states at the Fermi level at a higher substitution of Ni.