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Title: Tuning valley degeneracy with band inversion
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 N V = 4 to N V = 24, which could result in a corresponding increase in the thermoelectric figure of merit zT .  more » « less
Award ID(s):
1729149 1905277
Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Journal of Materials Chemistry A
Page Range / eLocation ID:
1588 to 1595
Medium: X
Sponsoring Org:
National Science Foundation
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