Two-dimensional Mott-Hubbard electrons in an artificial honeycomb   lattice
  Electrons in artificial lattices enable explorations of the impact of repulsive Coulomb interactions in a tunable system. We have trapped two-dimensional electrons belonging to a gallium arsenide quantum well in a nanofabricated lattice with honeycomb geometry. We probe the excitation spectrum in a magnetic field identifying novel collective modes that emerge from the Coulomb interaction in the artificial lattice as predicted by the Mott-Hubbard model. These observations allow us to determine the Hubbard gap and suggest the existence of a novel Coulomb-driven ground state. This approach offers new venues for the study of quantum phenomena in a controllable solid-state system. 
A. Singha, M. Gibertini, B. Karmakar, S. Yuan, M. Polini, G. Vignale,   M.I. Katsnelson, A. Pinczuk, L.N. Pfeiffer, K.W. Wes...
cond-mat.str-el cond-mat.mes-hall