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Anomalous phonon magnetic moments

Swati Chaudhary1,*,†, Carl P. Romao2,3,*,‡, and Dominik M. Juraschek4

  • *These authors contributed equally to this work.
  • †Contact author: swatichaudhary@issp.u-tokyo.ac.jp
  • ‡Contact author: carl.romao@cvut.cz
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Phys. Rev. Research 8, 023053 – Published 16 April, 2026

DOI: https://doi.org/10.1103/xzgb-33w5

Abstract

Circularly polarized phonons conventionally carry an angular momentum and a magnetic moment arising from circular motions of the atoms. Here, we present three anomalous cases that lead to phonon magnetic moments, which cannot be described in the conventional framework: rotationless axial phonons, which exhibit magnetic responses despite only carrying pseudoangular momentum, divergent gyromagnetic ratios of phonons, in which a magnetic moment is produced despite vanishing angular momentum, and anisotropic gyromagnetic ratios of phonons, which make the phonon angular momentum and magnetic moment noncollinear. Our results shed light on the origin and nature of phonon magnetism and suggest the existence of phononomagnetic hidden order.

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Phys. Rev. Research 8, 023053– Published 16 April, 2026
  • Received 6 May 2025
  • Accepted 1 March 2026
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