Observation of flat bands and singularity collapse in back-gated semiconductor artificial graphene

ORAL

Abstract

Electronic flat bands are key predicted features in tunable artificial graphene (AG) near M points in the Brillouin zone. Such dispersionless electron flat bands could support unconventional superconducting states. Here, we report the first direct observation of flat bands in semiconductor AG transistors where the electron density is tuned by applied voltage. Doublets observed in low temperature photoluminescence (PL) display a density dependence that is linked to the van-Hove singularity doublet near M points. We find that the doublets in PL persist for a large range of electron densities, suggesting a pinning of the Fermi energy in a flat band. Interestingly, as the temperature is lowered to below 10K, the lineshape of the doublet in PL spectra shows a dramatic temperature dependence in which the higher energy peak quickly collapses. This unexpected temperature dependence suggests possible formation of electron liquid states near the flat band at low temperature.

*Supported by NSF grant DMR-1306976 and DOE grant DE-SC0010695.

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Presenters

  • Ziyu Liu

    • Columbia University

Authors

  • Lingjie Du

    • Physics, Nanjing University
    • School of Physics, Nanjing University

  • Ziyu Liu

    • Columbia University

  • Loren Pfeiffer

    • Princeton University
    • Electrical Engineering, Princeton University
    • Electrical engineering, Princeton university
    • Princeton Univ
    • Department of Electrical Engineering, Princeton University
    • electrical engineering, Princeton
    • Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA

  • Michael Manfra

    • Physics and Astronomy, Purdue Univ
    • Department of Physics and Astronomy and Station Q Purdue, Birck Nanotechnology Center, School of Materials Engineering, School of Electrical and Computer Engineering, Purdue
    • Purdue Univ
    • Purdue University
    • Microsoft Quantum at Station Q Purdue
    • Department of Physics and Astronomy, Birck Nanotechnology Center, Microsoft Quantum Purdue, School og Materials Engineering & School of Electrical and Computer Engineering, P
    • Physics and Astronomy, Purdue University
    • Department of Physics and Astronomy and Station Q Purdue, Purdue University
    • Department of Physics and Astronomy and Microsoft Quantum Purdue, Purdue University, West Lafayette, Indiana 47907 USA
    • Department of Physics and Astronomy, PURDUE UNIVERSITY
    • Department of Physics and Astronomy, Microsoft Quantum Purdue, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
    • Physics, Purdue University

  • Aron Pinczuk

    • Columbia University