- Letter
Orbital angular momentum of azimuthal spin waves
Phys. Rev. B 113, L100410 – Published 19 March, 2026
DOI: https://doi.org/10.1103/l1x7-t8pn
Abstract
In the context of a growing interdisciplinary interest in the angular momentum of wave fields, the spin-wave case has yet to be fully explored, with the extensively studied notion of spin transport being only part of the broader picture. Here we report experimental evidence for nonzero magnon orbital angular momentum inside magnetic disk by resolving the frequency splitting between magnon modes with counterrotating wavefronts and thereby avoiding formation of azimuthal standing waves. This requires an unambiguous formulation of spin and orbital angular momenta for spin waves, which we provide in full generality taking advantage of a systematic application of quantum field theory techniques as detailed in a companion paper [T. Valet et al., Phys. Rev. B 113, 104437 (2026)]. The results unequivocally establish magnetic dipole-dipole interactions as a magnetic-field controllable spin-orbit interaction for magnons. Our findings open a new research direction, leveraging the spectroscopic readability of angular momentum for azimuthal spin waves and other related systems.
