Ultrafast relativistic response of Photo-excited Carriers in Graphene

ORAL

Abstract

Understanding the ultrafast non-equilibrium dynamics of photocarriers in graphene's unique relativistic band structure is important for the development of such high-speed, graphene-based photonic devices and also from a fundamental point of view. Here, we directly demonstrate the relativistic nature of a non-equilibrium gas of electrons and holes photogenerated in a graphene monolayer as early as 100 femtoseconds (fs) after photoexcitation. We photoexcited carriers in graphene and then measured the time-resolved, pump-induced change in reflection at various visible probe photon energies. We observe a nonlinear scaling in the Drude-like optical conductivity of the photocarriers with respect to their density, in striking contrast to the linear scaling expected from conventional materials with parabolic dispersion relations.

*Supported by University of California President's (UCOP) program on Carbon Nanostructures.

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Authors

  • J. Lee

    • CINT, Los Alamos National Laboratory

  • K.M. Dani

    • CINT, Los Alamos National Laboratory

  • R. Sharma

    • Theoretical Division, Los Alamos National Laboratory

  • Aditya Mohite

    • LANL
    • CINT, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • A.M. Dattelbaum

    • CINT, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • H. Htoon

    • LANL
    • CINT, Los Alamos National Laboratory
    • Los Alamos National Lab

  • Antoinette Taylor

    • CINT, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • R.P. Prasankumar

    • CINT, Los Alamos National Laboratory
    • Los Alamos National Laboratory

  • C.M. Galande

    • Dept. of Mechanical Engineering and Materials Science, Rice University

  • Pulickel M. Ajayan

    • Rice University
    • Dept. of Mechanical Engineering and Materials Science, Rice University