Dimer rattling mode induced low thermal conductivity in an excellent acoustic conductor.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33060588.
- Also identified by DOI 10.1038/s41467-020-19044-w and PMC identifier 7566455.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
A solid with larger sound speeds usually exhibits higher lattice thermal conductivity. Here, we report an exception that CuP<sub>2</sub> has a quite large mean sound speed of 4155 m s<sup>-1</sup>, comparable to GaAs, but single crystals show very low lattice thermal conductivity of about 4 W m<sup>-1</sup> K<sup>-1</sup> at room temperature, one order of magnitude smaller than GaAs. To understand such a puzzling thermal transport behavior, we have thoroughly investigated the atomic structures and lattice dynamics by combining neutron scattering techniques with first-principles simulations. This compound crystallizes in a layered structure where Cu atoms forming dimers are sandwiched in between P atomic networks. In this work, we reveal that Cu atomic dimers vibrate as a rattling mode with frequency around 11 meV, which is manifested to be remarkably anharmonic and strongly scatters acoustic phonons to achieve the low lattice thermal conductivity.