Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Monday: 2D Materials 1

O 18.16: Poster

Montag, 5. September 2022, 18:00–20:00, P4

Investigating the correlated ground state of metallic monolayer MoS₂ with scanning tunneling spectroscopy — •Camiel van Efferen, Jeison Fischer, Thomas Michely, and Wouter Jolie — II. Physikalisches Institut, Universität zu Köln, Germany

Using contactless chemical doping [1], we grow metallic monolayer 2H-MoS₂ on a graphene on Ir(111) substrate. Since this method leaves the surface accessible, we perform real space investigations of correlated behavior in metallic monolayer MoS₂ via scanning tunneling microscopy (STM) and spectroscopy (STS). In STS, we find a broad depression in the density of states around the Fermi level, of about 100 meV. Upon closer inspection, the depression is revealed to consist of a series of small gaps and peaks, spaced by 26-28 meV. This interval corresponds to a flat band in the phonon dispersion of MoS₂. The appearance of the peaks can be explained by strong coupling between the MoS₂ electrons and phonons at the high-symmetry K-point of the Brillouin zone, and may point to the formation of Holstein polarons. The behavior of the polarons is studied near grain boundaries, edges and defects, where the polaron bands are suprisingly seen to bend under the influence of charge.

[1] C. van Efferen et al., 2D Mater. 9 025026 (2022)