Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 11: Transition-metal dichalcogenides and boron nitride (with O)

HL 11.2: Talk

Monday, March 16, 2015, 12:00–12:15, ER 270

Coulomb-Induced Valley Coupling in Transition Metal Dichalcogenides — •Gunnar Berghäuser, Andreas Knorr, and Ermin Malic — Institut für Theoretische Physik, Nichtlineare Optic und Quantenelektronik, Technische Universität Berlin, Germany

Within a microscopic model we investigate the impact of Coulomb-induced intervalley coupling on the optical properties of transition metal dichalcogenides (TMDs). Our approach is based on the density matrix formalism and allows an analytical treatment of the excitonic absorption under the influence of intervalley coupling. We find that the strong Coulomb interaction in these atomically thin 2-dimensional materials couples resonant excitonic states in K and K’ valleys [1]. This coupling leads to a splitting of excitonic absorption peaks in the range of the trion binding energy. We further investigate the impact of experimentally accessible parameters, such as doping, dielectric environment, and the detuning of resonant states in the K and K’ valley, on the intervalley coupling. The gained insights are of crucial importance for the application of TMDs in valleytronics.

Gunnar Berghäuser and Ermin Malic, "Analytical approach to excitonic properties of MoS₂", Phys. Rev. B 89, 125309 (2014)