Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 29: Poster II

HL 29.36: Poster

Tuesday, March 18, 2025, 18:00–20:00, P1

Strong coupling of metal nanoparticles and 2d semiconductors: Physics behind a minimal model — •Lara Greten and Andreas Knorr — Institut für Theoretische Physik, Technische Universität Berlin, Germany

Transition metal dichalcogenide monolayers (TMDCs) feature strong light-matter interaction, governd by tightly bound, 2d-delocalized excitons. Metal nanostructures exhibit localized plasmons allowing for extreme electric field enhancements on the nanoscale. Hybrids of TMDCs and metal nanoparticles combine excitons and plasmons and may reach strong coupling as shown in numerous experiments. These experimental results are typically quantified via the coupled oscillator model (COM) employing a phenomenological coupling constant as a fitting parameter. To provide physical background to this model, we develop an analytical theory based on a microscopic perspective of the material dynamics and Maxwell's equations [1]. The emergent minimal model [2] provides a clear physical interpretation that highlights the importance of the spatial dispersion of 2d excitons. Depending on geometry and material properties we derive analytic expressions for all coupling and dephasing constants in a COM combining three oscillators: plasmons, bright and momentum-dark excitons. Strong coupling, that manifests as a peak splitting in optical spectra, is observed between momentum-dark excitons and plasmons, while the weakly coupled bright exciton yields a distinct third peak.

[1] L. Greten et al., ACS photonics 11.4, 1396-1411 (2024)

[2] L. Greten et al., arXiv preprint arXiv:2410.16796 (2024)

Keywords: Exciton; Plasmon; Metal Nanoparticle; Transition Metal Dichalchogenides; Strong Coupling