Ad-atoms on semiconductor surfaces as a versatile lab to study strongly correlated electrons

Adatom systems on semiconductors such as Sn:Si(111), Pb:Pb(111), and Sn:Ge(111) have been proposed to realize single band (extended) Hubbard models on a triangular lattice. In 2018 we predicted chiral d-wave superconductivity in these strongly correlated system upon hole-doping. The superconductivity was found in 2020, and in 2023 the chiral d-wave symmetry was confirmed. Building on this initial success, we continued our hunt for new adatom lattices and now propose transition-metal adatom systems on the 3C-SiC(111) surface. More specifically Ti, V, and Cr, adatom lattices turn out to realize strongly correlated Hubbard models with two low energy bands at different filling which show Dirac cones and extremely flat bands in their dispersion relation. Preliminary calculations with DFT and DMFT demonstrate, that these systems realize Mott insulating spin lattices and heavy Dirac semimetals on triangular lattice geometries which might offer an excellent platform to study the interplay of a topologically non-trivial bandstructure together with strong electronic correlations.