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TT: Fachverband Tiefe Temperaturen

TT 66: 2D Materials: Electronic structure, excitations, etc. – Poster (joint session O/TT)

TT 66.8: Poster

Mittwoch, 11. März 2026, 18:00–20:00, P2

Beyond the Gamma point: Scanning tunneling spectroscopy on MoS₂/graphene/Ir(111) — Borna Pielić^1,2, Dino Novko², Nina Girotto Erhardt², Vito Despoja², Alice Bremerich¹, Sumanasa Begur Prakash¹, •Robin Ohmann¹, and Carsten Busse¹ — ¹Universität Siegen, Walter-Flex-Str. 3, 57068 Siegen, Germany — ²Institute of Physics, Bijenička cesta 46, 10000 Zagreb, Croatia

Scanning tunneling spectroscopy (STS) reveals information about the band structure of surfaces by measuring the local density of states, and it also allows detection of quasiparticles. For semiconducting transition-metal dichalcogenides the conduction- and valence-band edges have been readily explored with this method. However, STS studies at higher energies than the Γ-point are limited. Here, we investigate epitaxially grown monolayer islands of MoS₂ on graphene/Ir(111) using STS at low-temperature (T=10 K). Specifically, we employ the constant-current STS method, which enables easier access to spectroscopic features with higher energies, than the more commonly used constant-height STS. We find several peaks a few hundred meV above the Γ-point. We do not see them on graphene, allowing us to exclude substrate- or tip-related effects. When measured near the step edge of an island, these peaks bend closer to the Fermi level, similar to the peak at the Γ-point. Their appearance also varies depending on tip condition and intercalation. Our observations cannot be explained in a single-particle picture. Possible many-body models, such as phonon assisted inelastic tunneling or plasmarons are discussed.

Keywords: Scanning tunneling spectroscopy; Scanning tunneling microscopy; 2D materials; Transition Metal Dichalcogenides; Many-body interactions