Abstract

In this talk I’ll discuss recent optical and transport results obtained in a high-mobility two-dimensional electron gas confined in a GaAs quantum well and subjected to a lateral potential with honeycomb topology [1,2,3]. By tuning the properties of the honeycomb lattice with a gate voltage and a magnetic field we were able to drive the system into localized or delocalized transport regimes. In this latter case we probed the cyclotron spectrum by means of inelastic light scattering and we identified a novel low-lying excitation at high magnetic fields with unexpectedly large oscillator strength. I will argue in the talk that this new gapped mode is a direct manifestation of the modification of the excitation spectra predicted by the Hubbard model [4]. Since the Hubbard model underpins the essential physics of Mott insulators, our approach offers new venues for experimental simulation of quantum phenomena in a controllable solid-state systems.

• work done in collaboration with A. Singha, M. Gibertini, M. Polini, B. Karmakar, G. De Simoni, A. Pinczuk, G. Vignale, L.N. Pfeiffer, K.W. West

[1] M. Gibertini et al. Phys. Rev. B RC 79 , 241406 (2009)

[2] G. De Simoni et al. arXiv:1007.3168

[3] A. Singha et al. in preparation

[4] J. Hubbard. Proc. R. Soc. Lond. A 281 , 401 (1964)