Microscopic theory of cavity-confined monolayer semiconductors: polariton-induced valley relaxation and the prospect of enhancing and controlling the valley pseudospin by chiral strong coupling

Abstract

We apply a microscopic theory of exciton-polaritons in cavity-confined monolayer transition-metal dichalcogenides including both optical polarizations in the monolayer plane, allowing to describe how chiral cavity photons interact with the valley degrees of freedom of the active material. Upon polariton formation, the degenerate excitons inhabiting the two inequivalent valleys are shown to assume bonding and antibonding superpositions as a result of cavity-mediated intravalley interactions combined with intervalley Coulomb interactions. This is representative of a polariton-induced coherent mixing of the valley polarization. In combination with disorder, this mixing is prone to open a new valley relaxation channel which attains significance with increasing cavity coupling. Importantly, we show that optical cavities with an asymmetric reflectance of left- and right-handed circularly-polarized photons offer a considerably more robust platform to realize a conserved valley polarization, as the valley localization of excitons is reinstated by an asymmetric Rabi splitting which lifts their degeneracy. Moreover, we show this degeneracy lifting to allow for wavelength-selective access to the valley pseudospin by means of a polariton-induced chiral Stark effect, offering interesting opportunities for valleytronic applications.

9 pages, 4 figures

References in corpus (10)

• Valley polarization in MoS2 monolayers by optical pumping
• Strong light-matter coupling in two-dimensional atomic crystals
• Exciton Binding Energy of Monolayer WS2
• Robust optical emission polarization in MoS2 monolayers through selective valley excitation
• Valley susceptibility of an interacting two-dimensional electron system
• Topological Polaritons
• Exciton Valley Dynamics probed by Kerr Rotation in WSe2 Monolayers
• Ultrafast Manipulation of Valley Pseudospin
• Two-dimensional metal-chalcogenide films in tunable optical microcavities
• Observation of macroscopic valley-polarized monolayer exciton-polaritons at room temperature

Cited by in corpus (3)

• Chiral Polaritonics: Analytic Solutions, Intuition and its Use
• Emergent Haldane Model and Photon-Valley Locking in Chiral Cavities
• Mixed quantum-classical modeling of exciton-phonon scattering in solids: Application to optical linewidths of monolayer MoS2