Magneto transport properties of iron-containing Cobalt Monosilicide*

A new strategy in thermoelectrics focussed in this work arise from the interaction of topological electronic states on the thermoelectric properties of materials with nontrivial band structures. Recently, transition metal silicides with B20 crystal structure have been found to belong to the class of topologically nontrivial materials. The electronic structure of CoSi contains linear dispersion branches with nodal points located near the Fermi level. Therefore, CoSi is an interesting candidate to study the correlation between electronic structure and thermoelectric properties.
Micro wires of CoFeSi were prepared by FIB from samples grown by Bridgeman method. The morphology and chemical composition was analysed by TEM, EDX and XRD. Furthermore, the micro ribbons were contacted via lithography patterning. Afterwards, the temperature and magnetic field dependent transport properties were characterized.
The CoFeSi reveals a monocrystalline B20 crystal structure. We analysed the electrical transport for parallel and perpendicular field. In parallel field, we observe a negative magneto resistance switching to comparable high positive magneto resistance for low temperature. In perpendicular field, we see a positive magneto resistance increasing for low temperature.