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.

Phonon Collapse and Second-Order Phase Transition in Thermoelectric SnSe / Aseginolaza, Unai; Bianco, Raffaello; Monacelli, Lorenzo; Paulatto, Lorenzo; Calandra, Matteo; Mauri, Francesco; Bergara, Aitor; Errea, Ion. - In: PHYSICAL REVIEW LETTERS. - ISSN 1092-0145. - 122:7(2019). [10.1103/PhysRevLett.122.075901]

Phonon Collapse and Second-Order Phase Transition in Thermoelectric SnSe

Bianco, Raffaello;Monacelli, Lorenzo;Mauri, Francesco;
2019

Abstract

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.
2019
physics
01 Pubblicazione su rivista::01a Articolo in rivista
Phonon Collapse and Second-Order Phase Transition in Thermoelectric SnSe / Aseginolaza, Unai; Bianco, Raffaello; Monacelli, Lorenzo; Paulatto, Lorenzo; Calandra, Matteo; Mauri, Francesco; Bergara, Aitor; Errea, Ion. - In: PHYSICAL REVIEW LETTERS. - ISSN 1092-0145. - 122:7(2019). [10.1103/PhysRevLett.122.075901]
File allegati a questo prodotto
File Dimensione Formato  
Aseginolaza_Phonon Collapse_2019.pdf

solo gestori archivio

Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 1.8 MB
Formato Adobe PDF
1.8 MB Adobe PDF   Contatta l'autore

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1277486
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 86
  • ???jsp.display-item.citation.isi??? 78
social impact