Topological Metal of NaBi with Ultralow Lattice Thermal Conductivity and Electron-phonon Superconductivity

TL;DR

NaBi is a topological metal with unique properties including electron-phonon superconductivity and ultralow, anisotropic thermal conductivity, making it a promising platform for studying the interplay of topology, superconductivity, and thermal transport.

Contribution

This work identifies NaBi as a topological metal with combined superconducting and ultralow thermal conductivity properties using first-principles calculations.

Findings

NaBi exhibits band inversion and non-trivial surface states.

NaBi shows electron-phonon superconductivity consistent with experiments.

NaBi has extremely low, anisotropic thermal conductivity.

Abstract

By means of first-principles and \emph{ab initio} tight-binding calculations, we found that the compound of NaBi is a three-dimensional non-trivial topological metal. Its topological feature can be confirmed by the presence of band inversion, the derived effective Z$_2$ invariant and the non-trivial surface states with the presence of Dirac cones. Interestingly, our calculations further demonstrated that NaBi exhibits the uniquely combined properties between the electron-phonon coupling superconductivity in nice agreement with recent experimental measurements and the obviously anisotropic but extremely low thermal conductivity. The spin-orbit coupling effects greatly affect those properties. NaBi may provide a rich platform to study the relationship among metal, topology, superconductivity and thermal conductivity.