abstract: This talk considers efforts directed towards the design and exploration of novel electron states in artificial graphene structures that are realized in solid-state systems 1. We focus in particular on artificial honecycomb lattices realized by nanofabrication in semiconductor heterostructures. Our experiments in these nanofabricated lattices reveal striking interplays between electron interactions and geometrical constraints (topology). 2,3,4. In particular, we probed the excitation spectrum of electrons in the honeycomb lattice in a magnetic field identifying collective modes that emerged from the Coulomb interaction 5, as predicted by the Mott-Hubbard model 6. These observations allow us to determine the Hubbard gap and suggest the existence of a Coulomb-driven ground state 5. Studies of electrons confined to artificial lattices should provide key perspectives on strong electron correlation in condensed matter science 1.
1 M. Polini et al., Nature Nanotechnology 8, 625–633 (2013)
2 M. Gibertini et al. Phys. Rev. B RC 79, 241406 (2009)
3 C.H. Park and S.G. Louie, Nano Lett. 9, 1793 (2009).
4 G. De Simoni et al. Appl. Phys. Lett. 97, 132113 (2010)
5 A. Singha et al. Science 332, 1176 (2011)
6 J. Hubbard. Proc. R. Soc. Lond. A 281, 401 (1964)