Phonon Helicity Induced by Electronic Berry Curvature in Dirac Materials

Lun Hui Hu, Jiabin Yu, Ion Garate, Chao Xing Liu

Research output: Contribution to journalArticlepeer-review

Abstract

In two-dimensional insulators with time-reversal (TR) symmetry, a nonzero local Berry curvature of low-energy massive Dirac fermions can give rise to nontrivial spin and charge responses, even though the integral of the Berry curvature over all occupied states is zero. In this Letter, we present a new effect induced by the electronic Berry curvature. By studying electron-phonon interactions in BaMnSb2, a prototype two-dimensional Dirac material possessing two TR-related massive Dirac cones, we find that the nonzero local Berry curvature of electrons can induce a phonon angular momentum. The direction of this phonon angular momentum is locked to the phonon propagation direction, and thus we refer to it as "phonon helicity"in a way that is reminiscent of electron helicity in spin-orbit-coupled electronic systems. We discuss possible experimental probes of such phonon helicity.

Original languageEnglish (US)
Article number125901
JournalPhysical review letters
Volume127
Issue number12
DOIs
StatePublished - Sep 17 2021

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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