Coulomb drag of massless fermions in graphene

By Seyoung Kim, I. Jo, J. Nah, Z. Yao, Sanjay Kumar Banerjee, E. Tutuc. 2010

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Two layers of carriers in close proximity can, in certain conditions favor correlated electron states with no counterpart in the single layer physics. The most notable is the formation of pairs of electrons and holes residing in opposing layers (indirect excitons), which can flow with no dissipation [1]. Such phenomena have been observed in electron-electron or hole-hole double quantum wells in high magnetic fields, when the lowest Landau level in each layer is half-full, and pairs of carriers and vacancies residing in opposite layers form as a result of inter-layer interaction [2], as well as in trapped microcavity polaritons [3]. Graphene, a monolayer of carbon atoms in a honeycomb lattice [4, 5], offers a unique system to investigate electron physics in interacting bilayers. The zero energy band-gap in graphene allows a seamless transition between electrons and holes in each layer, and obviates the large inter-layer electric field required to simultaneously induce electrons and holes in GaAs/AlGaAs bilayers [6]. Moreover, theoretical arguments suggest that a closely spaced electron-hole graphene bilayer favors dipolar superfluidity at elevated temperatures [7]. Here we demonstrate independently contacted graphene bilayers, and investigate the Coulomb drag in this system.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/51ed156d33dc8b1d6d4798638fc1dfd9bbc6f4bc