Superior valley polarization and coherence of 2s excitons in monolayer WSe2

Abstract

We report experimental observation of 2s exciton radiative emission from monolayer tungsten diselenide, enabled by hexagonal boron nitride protected high-quality samples. The 2s luminescence is highly robust and persists up to 150K, offering a new quantum entity for manipulating the valley degree of freedom. Remarkably, the 2s exciton displays superior valley polarization and coherence than 1s under similar experimental conditions. This observation provides evidence that the Coulomb-exchange-interaction-driven valley-depolarization process, the Maialle-Silva-Sham mechanism, plays an important role in valley excitons of monolayer transition metal dichalcogenides.

References in corpus (13)

• Valley polarization in MoS2 monolayers by optical pumping
• The Valley Hall Effect in MoS2 Transistors
• Tightly bound excitons in monolayer WSe2
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
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• Measurement of high exciton binding energy in the monolayer transition-metal dichalcogenides WS2 and WSe2
• Helicity resolved Raman scattering of MoS2, MoSe2, WS2 and WSe2 atomic layers
• Ultrafast Manipulation of Valley Pseudospin
• Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
• Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
• Activation of new Raman modes by inversion symmetry breaking in type II Weyl semimetal candidate T'-MoTe2
• Intrinsic Phonon Bands in High-Quality Monolayer T' Molybdenum Ditelluride

Cited by in corpus (19)

• Magneto-photoluminescence of exciton Rydberg states in monolayer WSe${}_2$
• Luminescent emission of excited Rydberg excitons from monolayer WSe2
• Ground and Excited Exciton Polarons in Monolayer MoSe2
• Spinorial formulation of the GW-BSE equations and spin properties of excitons in 2D Transition Metal Dichalcogenides
• Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS${}_2$
• Enhancement of Exciton Valley Polarization in Monolayer MoS2 Induced by Scattering
• Anomalous Non-Hydrogenic Exciton Series in 2D Materials on High-$\kappa$ Dielectric Substrates
• Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time
• Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
• Exciton-polaritons in multilayer WSe${}_2$ in a planar microcavity
• Up- and Down-Conversion between Intra- and Inter-Valley Excitons in Waveguide Coupled Monolayer WSe2
• Direct Observation of Intravalley Phonon Scattering of 2s Excitons in MoSe${}_2$ and WSe${}_2$ Monolayers
• Magnetically tunable exciton valley coherence in monolayer WS${}_2$ mediated by the electron-hole exchange and exciton-phonon interactions
• Probing the bright exciton state in twisted bilayer graphene via resonant Raman scattering
• Kohn-Sham-Proca equations for ultrafast exciton dynamics
• Laser-field detuning assisted optimization of exciton valley dynamics in monolayer WSe${}_2$: Geometric quantum speed limit
• Motion of 2D exciton in momentum space leads to pseudospin distribution narrowing on the Bloch Sphere
• Long-lived populations of momentum- and spin-indirect excitons in monolayer WSe${}_2$
• Ellipticity-Controlled Bright-Dark Coherence Transition in Monolayer WSe2