Justin C. W. Song, Dmitry A. Abanin, Leonid S. Levitov
Recent experiments revealed an anomalous Coulomb drag in graphene, which is distinct from the canonical mechanism relying on momentum transfer between graphene layers. A new mechanism, proposed to explain the observations, involves vertical energy transfer between layers, which couples to charge flow via lateral heat currents and thermopower. The two mechanisms depend on distinct physical effects, resulting in a starkly different behavior, in particular in drag magnitude and sign near charge neutrality. Under realistic conditions, energy transport dominates in a wide temperature range, giving rise to a universal value of drag which is essentially independent of the electron-electron interaction strength, providing a unique probe of energy transport on the nanoscale. The new mechanism explains strong enhancement of drag observed in classically weak magnetic fields.
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http://arxiv.org/abs/1304.1450
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