A steady state approach for studying valley relaxation using optical vortex beam

Abstract

Spin-valley coupling in monolayer transition metal dichalcogenides gives rise to valley polarization and coherence effect, limited by intervalley scattering caused by exciton-phonon, exciton-impurity, and electron-hole exchange interaction (EHEI). We explore an approach to tune the EHEI by controlling excitons center of mass momentum (COM) utilizing the photon distribution of higher-order optical vortex beam. By virtue of this, we have observed excitons COM-dependent valley depolarization and decoherence which gives us the ability to measure the timescale associated with valley dynamics in the steady-state measurement. Our steady-state technique to probe the valley dynamics can open up a new paradigm to explore the physics of excitons in two-dimensional systems.

25 pages, 5 Manuscript figures, 7 Supplementary figures

References in corpus (7)

• Valley polarization in MoS2 monolayers by optical pumping
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Ultrafast Generation of Pseudo-magnetic Field for Valley Excitons in WSe2 Monolayers
• Exciton Valley Dynamics probed by Kerr Rotation in WSe2 Monolayers
• Ab initio calculations of ultra-short carrier dynamics in 2D materials: valley depolarization in single-layer WSe${}_2$
• Dark excitons and the elusive valley polarization in transition metal dichalcogenides
• Spin-valley relaxation and quantum transport regimes in two-dimensional transition metal dichalcogenides

Cited by in corpus (5)

• Strain control of exciton and trion spin-valley dynamics in monolayer transition metal dichalcogenides
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Formation of dark excitons in monolayer transition metal dichalcogenides by a vortex beam: optical selection rules
• Probing spin dynamics of 2D excitons with twisted light
• Zero-Threshold PT-Symmetric Polariton-Raman Laser