Tuning valley degeneracy with band inversion

Michael Y. Toriyama*, Madison K. Brod, Lídia C. Gomes, Ferdaushi A. Bipasha, Badih A. Assaf, Elif Ertekin, G. Jeffrey Snyder

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)1588-1595
Number of pages8
JournalJournal of Materials Chemistry A
Volume10
Issue number3
DOIs
StatePublished - Jan 21 2022

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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