Valley polarization of singlet and triplet trions in WS${}_2$ monolayer in magnetic fields

Abstract

The spectral signatures associated with different negatively charged exciton complexes (trions) in a WS${}_2$ monolayer encapsulated in hBN, are analyzed from low temperature and polarization resolved reflectance contrast (RC) and photoluminescence (PL) experiments, with an applied magnetic field. Based on results obtained from the RC experiment, we show that the valley Zeeman effect affects the optical response of both the singlet and the triplet trion species through the evolution of their energy and of their relative intensity, when applying an external magnetic field. Our analysis allows us to estimate a free electron concentration of $\sim 1.3\cdot 10^{11}$ cm${}^{-2}$. The observed evolutions based on PL experiments on the same sample are different and can hardly be understood within the same simple frame highlighting the complexity of relaxation processes involved in the PL response.

7 pages, 4 figures; source file corrected

References in corpus (7)

• Valley polarization in MoS2 monolayers by optical pumping
• Measurement of the optical dielectric function of transition metal dichalcogenide monolayers: MoS2, MoSe2, WS2 and WSe2
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Optical response of monolayer, few-layer and bulk tungsten disulfide

Cited by in corpus (8)

• Exciton-polaron interactions in monolayer WS${}_2$
• Excitonic complexes in $n$-doped WS${}_2$ monolayer
• Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
• Neutral and charged dark excitons in monolayer WS${}_2$
• Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS${}_2$
• Valley Degree of Freedom in Two-Dimensional van der Waals Materials
• Emergence of 6-particle "hexciton'' states in WS${}_2$ and MoSe${}_2$ monolayers
• Valley Emission and Upconversion in Isotopically Engineered Monolayer WS${}_2$ under Resonant Excitation