Anomalously Suppressed Thermal Conduction by Electron-Phonon Coupling in Charge-Density-Wave Tantalum Disulfide.

ABSTRACT: Charge and thermal transport in a crystal is carried by free electrons and phonons (quantized lattice vibration), the two most fundamental quasiparticles. Above the Debye temperature of the crystal, phonon-mediated thermal conductivity (? L) is typically limited by mutual scattering of phonons, which results in ? L decreasing with inverse temperature, whereas free electrons play a negligible role in ? L. Here, an unusual case in charge-density-wave tantalum disulfide (1T-TaS2) is reported, in which ? L is limited instead by phonon scattering with free electrons, resulting in a temperature-independent ? L. In this system, the conventional phonon-phonon scattering is alleviated by its uniquely structured phonon dispersions, while unusually strong electron-phonon (e-ph) coupling arises from its Fermi surface strongly nested at wavevectors in which phonons exhibit Kohn anomalies. The unusual temperature dependence of thermal conduction is found as a consequence of these effects. The finding reveals new physics of thermal conduction, offers a unique platform to probe e-ph interactions, and provides potential ways to control heat flow in materials with free charge carriers. The temperature-independent thermal conductivity may also find thermal management application as a special thermal interface material between two systems when the heat conduction between them needs to be maintained at a constant level.

SUBMITTER: Liu H 

PROVIDER: S-EPMC7284197 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature