The notion that phonons can carry pseudo-angular momentum has become popular in the last decade, with recent research efforts highlighting phonon chirality, Berry curvature of phonon band structure, and the phonon Hall effect. When a phonon is resonantly coupled to a crystal electric field excitation, a so-called vibronic bound state forms. Here, we observe angular momentum transfer of δJz = ±1ℏ between phonons and an orbital state in a vibronic bound state of a candidate quantum spin liquid. This observation has profound implications for the engineering of phonon band structure topology through chiral quasiparticle interactions.
@article{arxiv.2203.13361,
title = {Phonon Chirality Induced by Vibronic-Orbital Coupling},
author = {Yun-Yi Pai and Claire E. Marvinney and Liangbo Liang and Ganesh Pokharel and Jie Xing and Haoxiang Li and Xun Li and Michael Chilcote and Matthew Brahlek and Lucas Lindsay and Hu Miao and Athena S. Sefat and David Parker and Stephen D. Wilson and Benjamin J. Lawrie},
journal= {arXiv preprint arXiv:2203.13361},
year = {2022}
}