Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 48: Two-dimensional Materials IV (joint session HL/CPP)
HL 48.7: Vortrag
Freitag, 5. April 2019, 11:15–11:30, H36
Theory of electron-exciton scattering in atomically thin semiconductors — Christian Fey1, Peter Schmelcher1, Atac Imamoglu2, and •Richard Schmidt3 — 1Universität Hamburg, Germany — 2ETH Zürich, Switzerland — 3MPI of Quantum Optics, Garching, Germany
Excitons interacting with charge carriers in van-der-Waals materials represent a new venue to study the many-body physics of strongly interacting Bose-Fermi mixtures. In order to derive an effective low-energy model for such systems we develop an exact diagonalization approach that predicts the bound and scattering properties of electron, excitons, and trions in two-dimensional semiconductors. By solving the quantum mechanical three-body problem of interacting charge carriers we obtain binding energies of excitons and trions that are in excellent agreement with quantum Monte Carlo predictions. Importantly, in our approach also excited states are accessible. This allows us to study exotic excited trion states as well as to predict the scattering phase shifts of electrons and excitons. From these results we derive an effective low-energy model of exciton-electron scattering that can serve as an input to advanced many-body techniques. As a demonstration we study the recently observed exciton Fermi polarons, and we show that effective range corrections predicted by our model have a substantial impact on the optical absorption spectrum of charge-doped transition-metal dichalcogenides. Our approach can be applied to a plethora of many-body phenomena realizable in atomically thin semiconductors ranging from exciton lattices and localization to induced superconductivity.