Thermoelectric and galvanomagnetic properties of topologically non-trivial (Co-M)Si semimetals (M = Fe, Ni) at high temperatures

We present experimental and theoretical results on electronic structure, galvanomagnetic, and thermoelectric properties (Hall coefficient, electrical resistivity, and Seebeck coefficient) of Co 1 − x M x Si ( M = Fe, Ni; x = 0–0.1) compounds at temperatures from 80 K to 800 K. CoSi is a long known promising thermoelectric semimetal. Recently, it was shown that CoSi and the CoSi-based alloys belong to the family of materials with a topologically nontrivial electronic structure. We discuss possible connection of the observed dependences of the transport properties on temperature and alloy composition with ab initio electronic structure of the compounds. The electronic structure was calculated using density functional theory, and transport properties were analyzed in constant relaxation time, as well as in more realistic energy-dependent relaxation time approximations.