Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions
Journal article
Skelton, J. M., Burton, L. A., Parker, S. C., Walsh, A., Kim, C.-E., Soon, A., Buckeridge, J., Sokol, A. A., Catlow, C. R. A., Togo, A. and Tanaka, I. (2019). Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions. Physical Review Letters. 117, p. 075502. https://doi.org/10.1103/PhysRevLett.117.075502
Authors | Skelton, J. M., Burton, L. A., Parker, S. C., Walsh, A., Kim, C.-E., Soon, A., Buckeridge, J., Sokol, A. A., Catlow, C. R. A., Togo, A. and Tanaka, I. |
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Abstract | The layered semiconductor SnSe is one of the highest-performing thermoelectric materials known. We demonstrate, through a first-principles lattice-dynamics study, that the high-temperature Cmcm phase is a dynamic average over lower-symmetry minima separated by very small energetic barriers. Compared to the low-temperature Pnma phase, the Cmcm phase displays a phonon softening and enhanced three-phonon scattering, leading to an anharmonic damping of the low-frequency modes and hence the thermal transport. We develop a renormalization scheme to quantify the effect of the soft modes on the calculated properties, and confirm that the anharmonicity is an inherent feature of the Cmcm phase. These results suggest a design concept for thermal insulators and thermoelectric materials, based on displacive instabilities, and highlight the power of lattice-dynamics calculations for materials characterization. |
Year | 2019 |
Journal | Physical Review Letters |
Journal citation | 117, p. 075502 |
Digital Object Identifier (DOI) | https://doi.org/10.1103/PhysRevLett.117.075502 |
Web address (URL) | https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.075502 |
Publication dates | |
10 Aug 2016 | |
Publication process dates | |
Accepted | 13 Jan 2016 |
Deposited | 21 Oct 2019 |
Accepted author manuscript | License File description Published version File Access Level Open |
https://openresearch.lsbu.ac.uk/item/8846w
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