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TT: Fachverband Tiefe Temperaturen

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

TT 16.1: Vortrag

Montag, 18. März 2024, 15:00–15:15, MA 005

Electronic and magnetic properties of single chalcogen vacancies in MoS₂/Au(111) — Sergey Trishin¹, •Christian Lotze¹, Nils Krane², and Katharina J. Franke¹ — ¹Fachbereich Physik, Freie Universität Berlin, Germany — ²nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) are considered highly promising platforms for next-generation optoelectronic devices. Because of their 2D structure, the performance of potential devices is strongly impacted by defects. Nowadays a lot of research aims to optimize growth methods towards defect-free TMDCs. However, defect engineering has also gained a lot of attention, as it may allow for control and design of new properties of 2D materials.

Here, we create single S vacancies in a monolayer of MoS₂ that was grown on Au(111). Using combined scanning tunneling and atomic force microscopy, we show that these defects are negatively charged and give rise to a Kondo resonance. The latter reveals the presence of an unpaired electron spin that is exchange-coupled to the underlying metal substrate. The strength of the exchange coupling depends on the density of states at the Fermi level, which is modulated by the moiré structure of the MoS₂ lattice and the Au(111) substrate. We also show that in the absence of direct hybridization of MoS₂ with the metal substrate, the S vacancy remains charge-neutral. Our results suggest that defect engineering may be used to induce and tune magnetic properties of otherwise nonmagnetic materials.

Keywords: TMDC; MoS2; STM; defects; scanning tunnelling microscopy