Strongly correlated electrons on a honeycomb lattice

Strongly correlated electron systems have fascinated physicists for decades. It started by the study of the metal-insulator transition also known as the Mott transition (Nobel prize 1977) which was observed in transition metal oxides, like for instance V2O3 in the late 1960’s. This transition occurs when it is energetically favorable for the system to localize electrons when the Coulomb interaction between them becomes large compared to their kinetic energy. The study of strongly correlated electron systems continued and celebrated successes with the discovery of high Tc superconductivity in 1986 (Nobel prize 1987). The high Tc superconducting state, in which the material has zero resistance, is observed in certain Mott insulators upon doping by charge carriers and the mechanism still needs to be revealed.