Observation of flat bands in gated semiconductor artificial graphene

Abstract

Flat bands near M points in the Brillouin zone are key features of honeycomb symmetry in artificial graphene (AG) where electrons may condense into novel correlated phases. Here we report the observation of van Hove singularity doublet of AG in GaAs quantum well transistors, which presents the evidence of flat bands in semiconductor AG. Two emerging peaks in photoluminescence spectra tuned by backgate voltages probe the singularity doublet of AG flat bands, and demonstrate their accessibility to the Fermi level. As the Fermi level crosses the doublet, the spectra display dramatic stability against electron density, indicating interplays between electron-electron interactions and honeycomb symmetry. Our results provide a new flexible platform to explore intriguing flat band physics.

11 pages, 4 figures, and Supplementary Material

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• Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice
• Engineering artificial graphene in a two-dimensional electron gas
• Kohn-Luttinger superconductivity in graphene
• Making Massless Dirac Fermions from Patterned Two-Dimensional Electron Gases
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• Correlated physics in an artificial triangular anti-dot lattice
• Artificial electrostatic crystals: a new platform for creating correlated quantum states
• Sub-Sharvin conductance and incoherent shot-noise in graphene disks at magnetic field
• Lithography defined semiconductor moires with anomalous in-gap quantum Hall states
• Designing Flat Bands and Pseudo-Landau Levels in GaAs with Patterned Gates