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TT: Fachverband Tiefe Temperaturen

TT 16: 2D Materials I: Electronic Structure (joint session O/TT)

TT 16.4: Talk

Monday, March 18, 2024, 15:45–16:00, MA 005

Charge State-Dependent Symmetry Breaking of Atomic Defects in Transition Metal Dichalogenides — •Lysander Huberich¹, Feifei Xiang¹, Jonas Allerbeck¹, Preston A. Vargas², Riccardo Torsi³, Anne Marie Tan², Pascal Ruffieux¹, Roman Fasel¹, Oliver Gröning¹, Yu-Chuan Lin³, Richard Henning², Joshua Robinson³, and Bruno Schuler¹ — ¹Empa - nanotech@surfaces Laboratory, 8600 Dübendorf, Switzerland — ²University of Florida, Gainesville, FL, 32611, USA — ³The Pennsylvania State University, University Park, PA, 16802, USA

The electronic properties of atomically thin 2D materials are strongly influenced by occuring atomic defects and their interaction with the host lattice. Here we report on the direct imaging of charge state-dependent symmetry breaking of single rhenium dopants (Re_Mo) and negatively charged sulfur vacancies (Vac_S⁻) in mono- and bilayer MoS₂ by atomically-resolved STM and nc-AFM. While Vac_S⁻ occur in both the symmetric and the symmetry-broken state, Re_Mo exhibit charge-dependent symmetry breaking stabilized by the difference in substrate workfunction. The local lattice distortions and symmetry-broken defect orbitals of Vac_S⁻ as well as Re_Mo⁰ and Re_Mo⁻¹ are attributed to the (pseudo-)Jahn-Teller effect. By mapping of electronic orbitals and geometric structures, we can disentangle effects of spatial averaging, charge multistability, configurational dynamics, and external perturbations that often mask the presence of local symmetry breaking. [Xiang, Huberich, et al., arXiv:2308.02201]

Keywords: Defects in 2D Materials; Jahn-Teller Effect; Symmetry-Breaking; Scanning Probe Microscopy; MoS2