2018/07/20 by Unai Aseginolaza, Raffaello Bianco, Lorenzo Monacelli +5 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Anharmonicity #Chalcogenide Semiconductor Thin Films #Condensed matter physics #Materials science #Phase (matter) #Phase transition #Phonon #Phonon scattering #Physics #Quantum mechanics #Scattering #Semiconductor #Thermal conductivity #Thermal properties of materials #Thermoelectric effect #Thermoelectric materials #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.122.075901
published as Phys. Rev. Lett. 122, 075901 (2019) · 6 pages, 5 figures
arxiv created 2018/07/20 · openalex publication_date 2019/02/22 · arxiv updated 2019/02/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 Pnma 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. We 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.