Abstract
Optical excitation of chiral phonons plays a vital role in studying the phonon-driven magnetic phenomena in solids. Transition metal dichalcogenides host chiral phonons at high symmetry points of the Brillouin zone, providing an ideal platform to explore the interplay between chiral phonons and valley degree of freedom. Here, we investigate the helicity-resolved magneto-Raman response of monolayer and identify a doubly degenerate Brillouin-zone-center chiral phonon mode at . Our wavelength- and temperature-dependent measurements show that this chiral phonon is activated through the resonant excitation of exciton. Under an out-of-plane magnetic field, the chiral phonon exhibits giant Zeeman splitting, which corresponds to an effective magnetic moment of . Moreover, we carry out theoretical calculations based on the morphic effects in nonmagnetic crystals, which reproduce the linear Zeeman splitting and Raman cross section of the chiral phonon. Our study provides important insights into lifting the chiral phonon degeneracy in an achiral covalent material, paving a route to excite and control chiral phonons.
- Received 17 July 2023
- Revised 21 March 2024
- Accepted 26 March 2024
DOI:https://doi.org/10.1103/PhysRevB.109.155426
©2024 American Physical Society