What happens when you place single transition metal atoms onto a SiC surface and arrange them into a perfect triangular pattern so that kinetic energy and Coulomb repulsion of the electrons are comparable? According to a new study by Henri Menke, Niklas Enderlein and collaborators, you get a remarkably versatile playground for some of the most sought-after phenomena in quantum materials – and even experimentally tunable by the choice of the atomic ingredient.
Reporting in Phys. Rev. Letters, the team, which includes FAU LMQ members Philipp Hansmann and Janina Maultzsch, studied the specific cases of titanium, vanadium, and chromium deposited on a silicon carbide (SiC) surface. Combining parameter-free first-principles methods with advanced many-body simulations, they found an unexpectedly rich variety of phenomena: Titanium hosts “massless” Dirac electrons – the same ultra-mobile carriers that made graphene famous – but now dressed in strong correlations. Vanadium turns the material into a magnetic Mott insulator on a triangular frustrated lattice, while chromium lies on the verge of a phase transition to a flat-band Fermi liquid, where electrons slow almost to a standstill and their mutual interactions take over.
This single, chemically tunable family thus spans from flat bands to Dirac cones, key ingredients behind today’s most exciting routes to topological states, magnetism, and unconventional superconductivity. The work places adatom lattices on SiC as an actually realizable and clean designer platform for engineering correlated quantum matter atom by atom.
For more information, see the publication in Physical Review Letters:
Engineering Correlated Dirac Fermions and Flat Bands on SiC with Transition-Metal Adatom Lattices
H. Menke, N. Enderlein, R. Gillen, Y.-T. Tseng, M. Bockstedte, J. Maultzsch, G. Sangiovanni, and P. Hansmann
Phys. Rev. Lett. 136, 246503 (2026)