Selective breakdown of phonon quasiparticles across superionic transition in CuCrSe 2

Journal Article (Journal Article)

Superionic crystals exhibit ionic mobilities comparable to liquids while maintaining a periodic crystalline lattice. The atomic dynamics leading to large ionic mobility have long been debated. A central question is whether phonon quasiparticles—which conduct heat in regular solids—survive in the superionic state, where a large fraction of the system exhibits liquid-like behaviour. Here we present the results of energy- and momentum-resolved scattering studies combined with first-principles calculations and show that in the superionic phase of CuCrSe 2 , long-wavelength acoustic phonons capable of heat conduction remain largely intact, whereas specific phonon quasiparticles dominated by the Cu ions break down as a result of anharmonicity and disorder. The weak bonding and large anharmonicity of the Cu sublattice are present already in the normal ordered state, resulting in low thermal conductivity even below the superionic transition. These results demonstrate that anharmonic phonon dynamics are at the origin of low thermal conductivity and superionicity in this class of materials.

Full Text

Duke Authors

Cited Authors

  • Niedziela, JL; Bansal, D; May, AF; Ding, J; Lanigan-Atkins, T; Ehlers, G; Abernathy, DL; Said, A; Delaire, O

Published Date

  • January 1, 2019

Published In

Volume / Issue

  • 15 / 1

Start / End Page

  • 73 - 78

Electronic International Standard Serial Number (EISSN)

  • 1745-2481

International Standard Serial Number (ISSN)

  • 1745-2473

Digital Object Identifier (DOI)

  • 10.1038/s41567-018-0298-2

Citation Source

  • Scopus