Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

SYTS: Symposium Interaction Effects and Correlations in twodimensional Systems - New Challenges for Theory

SYTS 1: Interaction effects and correlations in twodimensional systems - New challenges for theory

SYTS 1.1: Hauptvortrag

Mittwoch, 3. April 2019, 15:00–15:30, H1

Spectra of layered semiconductors from many-body perturbation theory — Thorsten Deilmann, Peter Krüger, Philipp Marauhn, and •Michael Rohlfing — Westfälische Wilhelms-Universität Münster, Institut für Festkörpertheorie, Münster, Germany

Two-dimensional systems pose particular challenges in describing electronic correlation effects: dielectric screening becomes highly anisotropic, and spatial confinement enhances the interaction between electrons and/or holes. Such effects modify both the electronic spectrum and excitonic binding effects, both of which also depend on sample thickness, substrate, and inter-layer wave function overlap.

These mechanisms can be described by ab-initio many-body perturbation theory (MBPT), notably by the GW approximation and the Bethe-Salpeter equation (GW-BSE). Its particular merit is the consideration of non-local dielectric screening effects.

We discuss spectral shifts of transition-metal dichalcogenides depending on the environment. Compared to an isolated monolayer, excitons are shifted to lower energy with increasing number of layers or when a monolayer is deposited on a substrate [1]. In addition, we discuss the competition between intra-layer excitons (i.e. with electron and hole on the same layer) and inter-layer excitons [2].

[1] M. Drüppel et al., Nature Comm. 8, 2117 (2017); Y. Niu et al., Nanomaterials 8, 725 (2018).

[2] A. Arora et al., Nature Comm. 8, 639 (2017); Nanoscale 10, 15571 (2018).