The role of phonon-phonon and electron-phonon scattering in thermal transport in PdCoO2.

Abstract

The layered metal oxide PdCoO2 is of fundamental interest in solid-state physics due to its unique nature as a two-dimensional electron gas. It is well known that electron-phonon scattering plays the leading role in the electrical transport of lots of materials; however, the influence of electron-phonon coupling on the thermal transport in PdCoO2 is rarely studied. Herewith we employ ab initio calculations to study the phonon lifetimes of PdCoO2 due to electron-phonon scattering and anharmonic phonon-phonon interactions. It is found that electron-phonon scattering has a large correction to the lattice thermal conductivity of PdCoO2 for both the in-plane and cross-plane directions, which is reduced by 21% and 27%, respectively. Moreover, the correction becomes larger and is more significant for the in-plane direction with decreasing temperature. As a result, the cross-plane lattice thermal transport overwhelms the in-plane value at low temperatures. This study provides useful guidance for the development of relevant devices involving two-dimensional electron gas systems.