Phonons provide a unique window into the coupled dynamics of lattice, spin, and electronic degrees of freedom in solids. Beyond their conventional role as lattice vibrations, their spectra and dynamics can be strongly modified by symmetry-breaking phenomena in the electronic and magnetic sectors. Understanding how such symmetry breaking is inherited by phonons offers new opportunities to probe and manipulate quantum materials.

In this talk, I will first discuss how time-reversal symmetry (TRS)–breaking orders in spin, orbital, and electronic sectors can be transferred to phonons, leading to an unusual magnetic response manifested as a giant phonon Zeeman effect[1,2,3]. I will highlight microscopic mechanisms, including orbital–lattice coupling, that give rise to this behavior [1]. I will then show how phonons can inherit signatures of more general TRS-breaking orders even in the absence of net magnetization leading to Raman-based probes of otherwise elusive hidden orders [4]. Finally, I will discuss how similar ideas extend to quantum-geometry–mediated photon–phonon coupling, offering a route toward controllable phonon excitation [5].

[1] S. Chaudhary, D. Juraschek, M. Rodriguez-Vega, and G. A. Fiete, Phys. Rev. B 110, 094401 (2024)
[2] D. Lujan, J. Choe, S. Chaudhary, G. Fiete, R. He, & Xiaoqin Li et al., PNAS, 121(11), e2304360121 (2024)
[3] Che, Mengqian, et al Phys. Rev, Lett. 134, 196906 (2025)
[4] R. Sutcliffe, K. Hart, S. Chaudhary, and A. Paramekanti. arXiv:2506.18978 (2025).
[5] S. Chaudhary, and T. Oka. arXiv:2508.04132 (2025).