Trions in MoS${}_2$ are quantum superpositions of intra- and intervalley spin states

Abstract

We report magneto-photoluminescence spectroscopy of gated MoS${}_2$ monolayers in high magnetic fields to 28 T. At B = 0T and electron density $n_s\sim 10^{12}c{m}^{-}2$, we observe three trion resonances that cannot be explained within a single-particle picture. Employing ab initio calculations that take into account three-particle correlation effects as well as local and non-local electron-hole exchange interaction, we identify those features as quantum superpositions of inter- and intravalley spin states. We experimentally investigate the mixed character of the trion wave function via the filling factor dependent valley Zeeman shift in positive and negative magnetic fields. Our results highlight the importance of exchange interactions for exciton physics in monolayer MoS${}_2$ and provide new insights into the microscopic understanding of trion physics in 2D multi-valley semiconductors for low excess carrier densities.

Main manuscript: 7 pages, 3 figures ; Supplemental material: 16 pages, 4 figures

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• Emergence of 6-particle "hexciton'' states in WS${}_2$ and MoSe${}_2$ monolayers
• Probing Dark Excitons in Monolayer MoS${}_2$ by NonLinear Two-Photon Spectroscopy
• Proximity-enhanced valley Zeeman splitting at the WS${}_2$/graphene interface
• Raman scattering excitation in monolayers of semiconducting transition metal dichalcogenides
• Electrical control of orbital and vibrational interlayer coupling in bi- and trilayer 2H-MoS${}_2$
• Energy shifts and broadening of excitonic resonances in electrostatically-doped semiconductors
• Magnetoexcitons and Massive Dirac Fermions in Monolayers of Transition Metal Dichalcogenides in a High Magnetic Field
• Trion-phonon interaction in atomically thin semiconductors