title: Excitonic Valley Effects in Monolayer WS2under 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 disulfide 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.
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Plechinger
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Nagler
authors.affiliation: Institute of Physics and Center for Nanotechnology, University of Münster , 48149 Münster, Germany.
authors.forename: Ashish
authors.initials: A
authors.lastname: Arora
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University , Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Andrés
authors.initials: A
authors.lastname: Granados Del Águila
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University , Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Mariana V
authors.initials: MV
authors.lastname: Ballottin
authors.affiliation: Institut für Theoretische Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Frank
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Steinleitner
authors.affiliation: Institut für Theoretische Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Gmitra
authors.affiliation: Institut für Theoretische Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Fabian
authors.affiliation: High Field Magnet Laboratory (HFML-EMFL), Radboud University , Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors.forename: Peter C M
authors.initials: PC
authors.lastname: Christianen
authors.affiliation: Institute of Physics and Center for Nanotechnology, University of Münster , 48149 Münster, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Bratschitsch
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schüller
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Korn
keywords: 2D materials; Transition metal dichalcogenides; WS2; excitons; valley polarization; valley splitting