First-principles theory of phonon magnetic moment

ORAL

Abstract

Chiral phonons have recently been shown to possess finite magnetic moment that consists of both nuclei and electron contributions. Classical (using Born effective charge) and quantum theories for the electron’s contribution have both been developed. However, the two theories carry essential differences in handling the geometric effects, and quantitative comparisons between the two theories are missing in realistic materials. Here, we developed a first-principles scheme to calculate phonon magnetic moment from quantum theory. We found observable magnetic moments of chiral phonon modes in a gated two-dimensional material. In contrast, the magnetic moments vanish according to classical theory. This contrast highlights the central role of geometric effects in phonon magnetic moments. In addition, the magnetic moments have significant electric-field tunability and mode selectivity. Our numerical methods and predictions open a new route to finding dynamical multiferroicity in realist material systems.

*First-principles calculations and theoretical analysis are mainly supported by DOE SC0012509.

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Presenters

  • Xiaowei Zhang

    • University of Washington

Authors

  • Xiaowei Zhang

    • University of Washington

  • Chong Wang

    • University of Washington
    • Carnegie Mellon University

  • Yafei Ren

    • University of Washington

  • Ting Cao

    • University of Washington
    • Department of Materials Science & Engineering, University of Washington

  • Di Xiao

    • University of Washington
    • 1. Department of Materials Science & Engineering, University of Washington, Seattle WA 98915 2. Department of Physics, University of Washington, Seattle WA 98915
    • Department of Materials Science & Engineering, Department of Physics, University of Washington; Pacific Northwest National Laboratory