Electronic Instability and Anharmonicity in SnSe

Abstract

The binary compound SnSe exhibits record high thermoelectric performance, largely because of its very low thermal conductivity. The origin of the strong phonon anharmonicity leading to the low thermal conductivity of SnSe is investigated through first-principles calculations of the electronic structure and phonons. It is shown that a Jahn-Teller instability of the electronic structure is responsible for the high-temperature lattice distortion between the Cmcm and Pnma phases. The coupling of phonon modes and the phase transition mechanism are elucidated, emphasizing the connection with hybrid improper ferroelectrics. This coupled instability of electronic orbitals and lattice dynamics is the origin of the strong anharmonicity causing the ultralow thermal conductivity in SnSe. Exploiting such bonding instabilities to generate strong anharmonicity may provide a new rational to design efficient thermoelectric materials.

References in corpus (5)

• Giant Anharmonic Phonon Scattering in PbTe
• Low thermal conductivity and triaxial phononic anisotropy of SnSe
• Anharmonicity in the high-temperature Cmcm phase of SnSe: soft modes and three-phonon interactions
• Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics
• Phonon anharmonicity and negative thermal expansion in SnSe

Cited by in corpus (3)

• Phonon anharmonicity: a pertinent review of recent progress and perspective
• Electron-phonon coupling and electronic thermoelectric properties of n-type PbTe driven near the soft-mode phase transition via lattice expansion
• An unlikely route to low lattice thermal conductivity: small atoms in a simple layered structure