Dominant two-dimensional electron-phonon interactions in the bulk Dirac semimetal Na3Bi

TL;DR

This study reveals that in the bulk Dirac semimetal Na3Bi, electron-phonon interactions are mainly two-dimensional, with a specific in-plane phonon mode influencing charge transport and inducing a phase transition to a Weyl semimetal.

Contribution

The paper identifies and characterizes a dominant 2D electron-phonon interaction in Na3Bi, advancing understanding of low-dimensional effects in bulk topological materials.

Findings

Discovery of a 2D optical phonon mode with strong e-ph interactions.

Identification of this mode's role in charge transport.

Induction of a dynamical phase transition to Weyl semimetal.

Abstract

Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and phase transitions due to their peculiar low-energy band structure. Yet the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here we show that electron-phonon (e-ph) interactions in a prototypical bulk DSM, Na3Bi, are predominantly two-dimensional (2D). Our first-principles calculations discover a 2D optical phonon with strong e-ph interactions associated with in-plane vibrations of Na atoms. We show that this 2D mode governs e-ph scattering and charge transport in Na3Bi, and induces a dynamical phase transition to a Weyl semimetal. Our work advances quantitative analysis of electron interactions in topological semimetals and reveals dominant low-dimensional interactions in bulk quantum materials.