Dominant Two-Dimensional Electron-Phonon Interactions in the Bulk Dirac Semimetal Na3Bi

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 reveal 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 the quantitative analysis of electron interactions in Na3Bi and reveals a dominant low-dimensional interaction in a bulk Dirac semimetal.

Automated summary

Bulk Dirac semimetals (DSMs), such as Na3Bi, exhibit unconventional transport properties and phase transitions, but the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here, we use first-principles calculations to show that electron-phonon (e-ph) interactions in Na3Bi are predominantly two-dimensional. We reveal a 2D optical phonon with strong e-ph interactions associated with in-plane vibrations of Na atoms, which governs e-ph scattering and charge transport in Na3Bi and induces a dynamical phase transition to a Weyl semimetal.