Hot carrier cooling with Landau levels in graphene

ORAL

Abstract

Photo-excited hot carriers in homogeneous graphene can give rise to photocurrent under perpendicular magnetic field. In turn, this so-called photo-Nernst effect can be used to probe hot-carrier dynamics as modified by the formation of Landau levels. We have carried out an ultrafast optical pump-probe photocurrent study of hexagonal boron nitride encapsulated graphene devices in the quantum Hall regime. Photocurrent, which exhibits quantum oscillations, is observed when the laser spot is near the free edges of the graphene. The relaxation time of the photo-Nernst current shows a drastic change when the graphene's Fermi energy is tuned across a Landau level. Our observation points to a new means of probing and control of non-equilibrium carrier dynamics in the quantum regime.

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Authors

  • Xinghan Cai

    Department of Physics, University of Washington, Seattle, WA 98195, USA, Department of Physics, University of Washington

  • Sanfeng Wu

    Department of Physics, University of Washington, Seattle, WA 98195, USA, Department of Physics, University of Washington

  • You Lai

    National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA

  • David Cobden

    Department of Physics, University of Washington, Department of Physics, University of Washington, Seattle, WA 98195, USA, Univ of Washington, University of Washington

  • Zhiqiang Li

    National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA

  • Xiaodong Xu

    Department of Physics, University of Washington, Seattle, WA 98195, USA, University of Washington