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
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• Anomalous Raman Spectra and Thickness Dependent Electronic properties of WSe2
• 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 (8)

• 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
• Exciton-polaritons in multilayer WSe${}_2$ in a planar microcavity
• Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
• 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
• Long-lived populations of momentum- and spin-indirect excitons in monolayer WSe${}_2$