Excitonic valley effects in monolayer WS${}_2$ under high magnetic fields

Abstract

Transition-metal dichalcogenides can be easily produced as atomically thin sheets, exhibiting the possibility to optically polarize and read out the valley pseudospin of extremely stable excitonic quasiparticles present in these 2D semiconductors. Here, we investigate a monolayer of tungsten disulphide in high magnetic fields up to 30\,T via photoluminescence spectroscopy at low temperatures. The valley degeneracy is lifted for all optical features, particularly for excitons, singlet and triplet trions, for which we determine the g factor separately. While the observation of a diamagnetic shift of the exciton and trion resonances gives us insight into the real-space extension of these quasiparticles, magnetic field induced valley polarization effects shed light onto the exciton and trion dispersion relations in reciprocal space. The field dependence of the trion valley polarizations is in line with the predicted trion splitting into singlet and triplet configurations.

References in corpus (10)

• Valley polarization in MoS2 monolayers by optical pumping
• The Valley Hall Effect in MoS2 Transistors
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Probing the influence of dielectric environment on excitons in monolayer WSe2: Insight from high magnetic fields
• Magneto-optics in transition metal diselenide monolayers
• Optical investigation of monolayer and bulk tungsten diselenide (WSe${}_2$) in high magnetic fields

Cited by in corpus (6)

• Optical response of monolayer, few-layer and bulk tungsten disulfide
• Excitons and trions in monolayer transition metal dichalcogenides: A comparative study between the multiband model and the quadratic single-band model
• Luminescent emission of excited Rydberg excitons from monolayer WSe2
• Spectrum of exciton states in monolayer transition metal dichalcogenides: angular momentum and Landau levels
• Magneto photoluminescence measurements of tungsten disulphide monolayers
• Large g factor in bilayer WS${}_2$ flakes