期刊
PHYSICAL REVIEW LETTERS
卷 122, 期 7, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.122.075901
关键词
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资金
- Spanish Ministry of Economy and Competitiveness [FIS2016-76617-P]
- Department of Education, Universities and Research of the Basque Government
- University of the Basque Country [IT756-13]
- Material Physics Center
- Spanish Supercomputing Network [FI-2017-2-0007]
- PRACE [2017174186]
Since 2014 the layered semiconductor SnSe in the high-temperature Cmcm phase is known to be the most efficient intrinsic thermoelectric material. Making use of first-principles calculations we show that its vibrational and thermal transport properties are determined by huge nonperturbative anharmonic effects. We show that the transition from the Cmcm phase to the low-symmetry Prima is a second-order phase transition driven by the collapse of a zone border phonon, whose frequency vanishes at the transition temperature. Our calculations show that the spectral function of the in-plane vibrational modes are strongly anomalous with shoulders and double-peak structures. WC calculate the lattice thermal conductivity obtaining good agreement with experiments only when nonperturbative anharmonic scattering is included. Our results suggest that the good thermoelectric efficiency of SnSe is strongly affected by the nonperturbative anharmonicity.
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