Probing spin dynamics of 2D excitons with twisted light

Abstract

We propose a mechanism of intravalley spin-flip scattering in spin-valley coupled two dimensional systems by transferring momentum of light into exciton center of mass using optical vortex (OV) beams. By varying the dispersion of light using the topological charge of OV beam, we demonstrate a unique approach to control the intra-valley spin-flip scattering rate of excitons. From our photoluminescence measurements, we demonstrate that the intra-valley scattering rate in W-based TMDs can be tuned externally by OV beams. Variation of photoluminescence intensity with topological charges shows a crossover temperature (> 150 K), indicating competitions among time scales involving radiative recombination, spin-flip scattering, and thermal relaxations. Our proposed technique utilizing a structured light beam can open up a new approach to explore the physics of excitons in 2D systems.

arXiv comment14 pages, 3 figures (Main text); 13 pages, 12 figures (Supporting Information)

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Cited by in corpus (4)

• Formation of dark excitons in monolayer transition metal dichalcogenides by a vortex beam: optical selection rules
• Molecular and solid-state topological polaritons induced by population imbalance
• Photoexcitation of planar Wannier excitons by twisted photons
• Surface photoelectric effect by twisted photons as a source of twisted electrons