Transport properties of cobalt monosilicide and its alloys at low temperatures

The electrical resistivity and thermopower of cobalt monosilicide (CoSi) and dilute alloys of CoSi with iron at temperatures from 2 to 370 K are experimentally investigated. CoSi is a semimetal and considered to be a promising thermoelectric material. It crystallizes into the cubic structure without an inversion center. This feature suggests the existence of topologically nontrivial electronic states and makes CoSi a candidate for the Weyl semimetal class. The main goal of the study is to find experimental confirmation of this assignment. It is shown that the experimental temperature dependences of the electrical resistivity and thermopower of CoSi and Co$_{1-x}$Fe$_{x}$Si ($x$ = 0.04) at low temperatures cannot be interpreted within the standard theory of conductivity in metals and may be related to topological features of the electronic structure of this compound.