title: Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice.
abstract: Artificial crystal lattices can be used to tune repulsive Coulomb interactions between electrons. We trapped electrons, confined as a two-dimensional gas in a gallium arsenide quantum well, in a nanofabricated lattice with honeycomb geometry. We probed the excitation spectrum in a magnetic field, identifying collective modes that emerged 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 Coulomb-driven ground state.
authors.affiliation: National Enterprise for nanoScience and nanoTechnology, Istituto Nanoscienze-CNR, and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Singha
authors.forename: M
authors.initials: M
authors.lastname: Gibertini
authors.forename: B
authors.initials: B
authors.lastname: Karmakar
authors.forename: S
authors.initials: S
authors.lastname: Yuan
authors.forename: M
authors.initials: M
authors.lastname: Polini
authors.forename: G
authors.initials: G
authors.lastname: Vignale
authors.forename: M I
authors.initials: MI
authors.lastname: Katsnelson
authors.forename: A
authors.initials: A
authors.lastname: Pinczuk
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.forename: K W
authors.initials: KW
authors.lastname: West
authors.forename: V
authors.initials: V
authors.lastname: Pellegrini