Trions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>MoS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> are quantum superpositions of intra- and intervalley spin states
Julian Klein, Matthias Florian, Alexander Hötger, Alexander Steinhoff, Alex Delhomme, Takashi Taniguchi, Kenji Watanabe, F. Jahnke, Alexander W. Holleitner, M. Potemski, C. Faugeras, Andreas V. Stier, Jonathan J. Finley
Abstract
We report magnetophotoluminescence spectroscopy of gated ${\mathrm{MoS}}_{2}$ monolayers in high magnetic fields to 28 T. At $B=0$ T and electron density ${n}_{s}\ensuremath{\sim}{10}^{12} {\mathrm{cm}}^{\ensuremath{-}2}$, 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 nonlocal 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 ${\mathrm{MoS}}_{2}$ and provide insights into the microscopic understanding of trion physics in two-dimensional multivalley semiconductors for low excess carrier densities.