Alloying-induced enhancement of thermopower in the Dirac-semimetal system Cd3-xZnxAs2

Cd3As2 is one of the prototypical topological Dirac semimetals. Here, we manipulate the band inversion responsible for the emergence of Dirac nodes by alloying Cd3As2 with topologically trivial Zn3As2. The carrier density monotonically decreases and the resistivity is enhanced as x is increased. For larger x, the thermoelectric figure of merit exhibits comparably large values exceeding 0.3 at room temperature, due to the combined effects of a strong enhancement of the thermopower, an only moderate increase in the resistivity, and a suppression of the thermal conductivity. Complementary quantum-oscillation data and optical-conductivity measurements allow us to infer that the Dirac nodes are gapped out, and a band structure with a partly flat dispersion likely emerges in the higher-x region in Cd3-xZnxAs2.

Automated summary

Manipulating band inversion by alloying Cd3As2 with Zn3As2 can enhance the thermoelectric figure of merit and suppress thermal conductivity, leading to the emergence of a band structure with partly flat dispersion in the higher-x region of Cd3-xZnxAs2.