The Rotating Excitons in 2D Materials: Valley Zeeman Effect and Chirality

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2024-08, Vol.18 (8), p.n/a
• Main Authors: Cui, Yu, Ma, Xin‐Jun, Deng, Jia‐Pei, Li, Shao‐Juan, Yang, Ran‐Bo, Li, Zhi‐Qing, Wang, Zi‐Wu
• Format: Article
• Language: English
• Subjects: Angular momentum; Bilayers; chiralities; Chirality; Controllability; Elementary excitations; Excitons; Interlayers; Magnetic moments; phonon angular momenta; Rotating bodies; rotating excitons; Rotation; Transition metal compounds; transition metal dichalcogenides; Two dimensional materials; valley Zeeman effects; Zeeman effect
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.202400060

The rotational dynamics of the intralayer and interlayer excitons with their inherent momenta of inertia in the monolayer and bilayer transition metal dichalcogenides, respectively, where the new chirality of exciton is endowed by the rotational angular momentum, namely, the formations of left‐ and right‐handed excitons at the +K and −K valleys, respectively, is proposed. It is found that angular momenta exchange between excitons and its surrounding phononic bath result in the large fluctuation of the effective g‐factor and the asymmetry of valley Zeeman splitting observed in most recently experiments, both of which sensitively depend on the magnetic moments provided by the phononic environment. This rotating exciton model not only proposes a new controllable knob in valleytronics, but opens the door to explore the angular momentum exchange of the chiral quasiparticles with the many‐body environment. GA: Herein, the rotational dynamics of the excitons in monolayer and bilayer transition metal dichalcogenides are proposed, where the right‐ and left‐handed excitons can be defined by the rotational angular momentum. The exchange of angular momenta between the rotating excitons and their surrounding phononic bath results in the strong renormalization of the g‐factors, providing a reasonable explanation for the asymmetry of valley Zeeman splitting observed in experiments. Moreover, the chirality of phononic bath and phonon magnetic moment could be reflected directly by the valley Zeeman effect.