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O: Fachverband Oberflächenphysik
O 11: 2D Materials I: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)
O 11.7: Vortrag
Montag, 16. März 2020, 12:15–12:30, WIL C107
Time-dependent momentum distributions of bright and dark excitons in bulk WSe2 — •Shuo Dong1, Samuel Beaulieu1, Dominik Christiansen2, Maciej Dendzik1, Tommaso Pincelli1, Rui Patrick Xian1, Julian Maklar1, Malte Selig2, Andreas Knorr2, Martin Wolf1, Laurenz Rettig1, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Germany
Transition metal dichalcogenide semiconductors feature exceptional optoelectronic properties. The investigation of excited states in k-space provides access to optically-bright and dark states on equal footing. Here, we perform the momentum-resolved excited-state mapping in the entire first Brillouin zone of bulk WSe2 using time-resolved momentum microscopy. Upon resonant excitation of band gap, the bright excitons with trARPES signal in the K valleys rapidly scatter to finite-momentum dark excitons in the Σ valleys. We analyze the shape and size of momentum distribution of the excited state. Under the plane wave final state approximation, the Fourier transform of photoemission signal yields real-space image of excitonic wave function. Combined with a microscopic theoretical description of exciton dynamics, the momentum-resolved valley carrier distribution provides information of fundamental exciton properties, like size, binding energy and exciton-phonon coupling.