Intra- and inter-layer excitons of two-dimensional semiconductors on substrates and in magnetic fields

Excitonic states in two-dimensional semiconductors, in particular in transition-metal dichalcogenides (TMDC), exhibit characteristic optical properties combining spin selectivity with reduced dimension. They can be described by standard many-body perturbation theory (MBPT), notably by the GW method in combination with the Bethe-Salpeter equation. Due to their low-dimensional structure the excitons in these systems can easily be manipulated and tuned by external stimuli. Here we discuss in particular (i) energetic red-shifts of TMDC monolayer excitons due to a supporting substrate [1], (ii) the layer dependence of polarizability-related shifts at TMDC surfaces [2], and (iii) magnetic-field induced shift and splitting of intra- and inter-layer excitons [3,4,5].

[1] M. Drueppel et al., Nat. Comm. 8, 2117 (2017).

[2] R. Wallauer et al., Phys. Rev. B 102, 125417 (2020).

[3] A. Arora et al., Nat. Comm. 8, 639 (2017).

[4] T. Deilmann et al., Phys. Rev. Lett. 124, 226402 (2020).

[5] M.-C. Heissenbuettel et al., Nano Lett. 21, 5173 (2021).