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.
Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice / Singha, A., Gibertini, M., Karmakar, B., Yuan, S., Polini, M., Vignale, G., Katsnelson, M.I., Pinczuk, A., Pfeiffer, L.N., West, K.W., Pellegrini, V.. - In: SCIENCE. - ISSN 1095-9203. - 332:6034(2011), pp. 1176-1179. [10.1126/science.1204333]
Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice
Gibertini M.;
2011
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.
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