Issue 3, 2022

Tuning valley degeneracy with band inversion

Abstract

Valley degeneracy is a key feature of the electronic structure that benefits the thermoelectric performance of a material. Despite recent studies which claim that high valley degeneracy can be achieved with inverted bands, our analysis of rock-salt IV–VI compounds using first-principles calculations and k·p perturbation theory demonstrates that mere band inversion is an insufficient condition for high valley degeneracy; rather, there is a critical degree to which the bands must be inverted to induce multiple carrier pockets. The so-called “band inversion parameter” is formalized as a chemically-tunable property, offering a design route to achieving high valley degeneracy in compounds with inverted bands. We predict that the valley degeneracy of rock-salt IV–VI compounds can be increased from NV = 4 to NV = 24, which could result in a corresponding increase in the thermoelectric figure of merit zT.

Graphical abstract: Tuning valley degeneracy with band inversion

Supplementary files

Article information

Article type
Paper
Submitted
28 Sep 2021
Accepted
14 Dec 2021
First published
16 Dec 2021

J. Mater. Chem. A, 2022,10, 1588-1595

Author version available

Tuning valley degeneracy with band inversion

M. Y. Toriyama, M. K. Brod, L. C. Gomes, F. A. Bipasha, B. A. Assaf, E. Ertekin and G. J. Snyder, J. Mater. Chem. A, 2022, 10, 1588 DOI: 10.1039/D1TA08379A

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