Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions

Jonathan Skelton; Lee Burton; Stephen Parker; Aron Walsh; Chang-eun Kim; Aloysius Soon; John Buckeridge; Alexey A. Sokol; C. Richard A. Catlow; Atsushi Togo; Isao Tanaka

doi:10.1103/PhysRevLett.117.075502

Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions

Jonathan Skelton, Lee Burton, Stephen Parker, Aron Walsh, Chang-eun Kim, Aloysius Soon, John Buckeridge, Alexey A. Sokol, C. Richard A. Catlow, Atsushi Togo, Isao Tanaka

Research output: Contribution to journal › Article

66 Citations (Scopus)

126 Downloads (Pure)

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.

Original language	English
Article number	075502
Journal	Physical Review Letters
Volume	117
DOIs	https://doi.org/10.1103/PhysRevLett.117.075502
Publication status	Published - 10 Aug 2016

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Applying Long-Lived Metastable States in Switchable Functionality via Kinetic Control of Molecular Assembly

Raithby, P., Burrows, A., Carbery, D., Marken, F., Parker, S., Walsh, A. & Wilson, C.

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Data for "Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions"

Skelton, J. (Creator), Burton, L. (Researcher), Parker, S. (Supervisor), Walsh, A. (Project Leader), Kim, C. (Researcher), Soon, A. (Supervisor), Buckeridge, J. (Researcher), Sokol, A. A. (Researcher), Catlow, C. R. A. (Supervisor), Togo, A. (Researcher) & Tanaka, I. (Supervisor), University of Bath, 10 Aug 2016

DOI: 10.15125/BATH-00258, http://dx.doi.org/10.1103/PhysRevLett.117.075502

Dataset

Equipment

High Performance Computing (HPC) Facility

Steven Chapman (Manager)

University of Bath

Facility/equipment: Facility

Cite this

Skelton, J., Burton, L., Parker, S., Walsh, A., Kim, C., Soon, A., Buckeridge, J., Sokol, A. A., Catlow, C. R. A., Togo, A., & Tanaka, I. (2016). Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions. Physical Review Letters, 117, [075502]. https://doi.org/10.1103/PhysRevLett.117.075502

Anharmonicity in the High-Temperature Cmcm Phase of SnSe: Soft Modes and Three-Phonon Interactions. / Skelton, Jonathan; Burton, Lee; Parker, Stephen; Walsh, Aron; Kim, Chang-eun; Soon, Aloysius; Buckeridge, John; Sokol, Alexey A.; Catlow, C. Richard A.; Togo, Atsushi; Tanaka, Isao.

In: Physical Review Letters, Vol. 117, 075502, 10.08.2016.

Research output: Contribution to journal › Article

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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.",

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AB - 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.

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