Seminar: Dr. Wencan Jin | Auburn University
In-Person PHYS 401
Location
Physics : 401
Date & Time
October 10, 2024, 1:30 pm – 2:30 pm
Description
TITLE: "Exciton-activated phonon magnetic moment in monolayer MoS 2"
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. In this talk, I will present helicity-resolved magneto-Raman studies of monolayer MoS 2 , in which a doubly degenerate chiral phonon mode is found at ∼270cm−1. Our wavelength- and temperature-dependent measurements show that this chiral phonon is activated through the resonant excitation of A exciton. Under an out-of-plane magnetic field, the chiral phonon exhibits giant Zeeman splitting, which corresponds to an effective magnetic moment of ∼2.5μB. Finally, I will discuss the origin of the giant phonon magnetic moment using the picture of orbital-lattice coupling. 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.
Reference: Chunli Tang et al., Phys. Rev. B 109, 155426 (2024)
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. In this talk, I will present helicity-resolved magneto-Raman studies of monolayer MoS 2 , in which a doubly degenerate chiral phonon mode is found at ∼270cm−1. Our wavelength- and temperature-dependent measurements show that this chiral phonon is activated through the resonant excitation of A exciton. Under an out-of-plane magnetic field, the chiral phonon exhibits giant Zeeman splitting, which corresponds to an effective magnetic moment of ∼2.5μB. Finally, I will discuss the origin of the giant phonon magnetic moment using the picture of orbital-lattice coupling. 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.
Reference: Chunli Tang et al., Phys. Rev. B 109, 155426 (2024)
