Scanning tunneling microscopy has pioneered access to the subatomic world, yet its spectroscopic potential remains underused, especially for many-body phenomena in two-dimensional materials. In elastic tunneling, one reads not only single-particle energies but also the band renormalization arising from dielectric screening, electron–boson coupling, and strain, whereas the small inelastic fraction directly probes phonons, plasmons, and excitons, thus enabling fully electrical, non-light-assisted spectroscopy. By contrast with conventional area-averaging probes such as ARPES or Raman/EELS, STS offers sub-nanometre, junction-specific access to both occupied and unoccupied states.

MoS₂ is a 2D semiconductor with a direct band gap, strong exciton binding energy, high charge mobility, and high thermal conductivity. When placed on graphene, the coupling is commonly considered purely van der Waals, yet we show evidence for a covalent-like component; moreover, the MoS₂–graphene interaction strength can be tuned by self-intercalation, resulting in cumulative spectral shifts driven by variations in dielectric screening and strain.  In a comprehensive follow-up STS study of MoS₂/graphene, we reveal that Γ-side replicas, absent in the single-particle picture, imprint potential interlayer-polaron formation, i.e., coupling between graphene phonons and a MoS₂ Γ state, alongside multiphonon tip-assisted inelastic processes. 

While ARPES has established that plasmarons can strongly renormalize graphene’s π-band, yet direct STS evidence has remained elusive despite extensive studies. In p-doped graphene we resolve an unoccupied-side shoulder in the local density of states, which is in line with a state-of-the-art GW prediction for a plasmaron feature.

As an outlook, we have realized an atomically sharp MoS₂–TaS₂ junction, promising both for low-resistance ohmic contacts and as a 1D platform to explore many-body effects, where inelastic tunneling at the boundary between MoS₂ Γ-valence phonon coupling and the TaS₂ charge-density wave emerges as a key curiosity.

Join Zoom Meeting:

https://us06web.zoom.us/j/5081440931

Meeting ID: 508 144 0931

Seminar hosts: Juraj Krsnik i Borna Radatović