Topological states of thermoelectric Yb-filled skutterudites

The effects of topological states on the thermoelectric performance of a highly efficient thermoelectric Yb-filled ${\mathrm{CoSb}}₃$ skutterudite are investigated through combined ab initio calculations and electrical transport measurements. The nontrivial topological states are revealed by ab initio calculations and inferred from anomalous Hall conductivity and magnetoresistance. The linear bands associated with the topological states lead to low single-band effective mass and high carrier mobility, and consequently high power factor. Furthermore, the additional band minima due to filling the voids with Yb atoms raise the valley degeneracy, which favors the density-of-states effective mass and thus the Seebeck coefficient but scarcely changing the carrier mobility. These effects together contribute to the high power factor of Yb-filled ${\mathrm{CoSb}}₃$ skutterudite. Our results show that topological states play a crucial role in improving the performance of thermoelectric materials.