M. Titov, R. V. Gorbachev, B. N. Narozhny, T. Tudorovskiy, M. Schuett, P. M. Ostrovsky, I. V. Gornyi, A. D. Mirlin, M. I. Katsnelson, A. K. Geim, L. A. Ponomarenko
We propose a phenomenological model of the effect of Coulomb drag between two closely positioned graphene monolayers. Near charge neutrality, each of the layers contains two kinds of carriers (quasiparticles) with opposite electric charge -- electrons and holes, such that the quasiparticle and electric currents become noncollinear in the presence of external magnetic field. Precisely at the Dirac point, these currents are orthogonal to each other, giving rise to giant magneto-drag. The sign of the drag resistance depends on the strength of the electron-phonon interaction, as well as on the geometry of the sample. Away from the Dirac point, the quasi-particle current acquires a component in the direction of the electric current, leading to non-zero Hall drag. The results of the model agree with the experimental data in weak magnetic fields measured in double-layer graphene/boron-nitride heterostructures with the interlayer distance of 1 nm.
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http://arxiv.org/abs/1303.6264
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