Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 52: Transport: Graphene 2 (jointly with MA, HL, DY, DS, O)
TT 52.4: Vortrag
Freitag, 30. März 2012, 10:15–10:30, BH 334
Coulomb drag in graphene: perturbation theory — •Boris Narozhny1, Michael Titov2,3, Igor Gornyi3,4, and Pavel Ostrovsky3,5 — 1Institut für Theorie der Kondensierten Materie, Karlsruher Institut für Technologie, 76128 Karlsruhe, Germany — 2School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK — 3Institut für Nanotechnologie, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany — 4A.F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia — 5L.D. Landau Institute for Theoretical Physics RAS, 119334 Moscow, Russia
We study the effect of Coulomb drag between two closely positioned graphene monolayers. In the limit of weak electron-electron interaction and small inter-layer spacing d (µ1(2), T≪ v/d) the drag is described by a universal function of the chemical potentials of the layers µ1(2) measured in the units of temperature T. When both layers are tuned close to the Dirac point, then the drag coefficient is proportional to the product of the chemical potentials ρD∝µ1µ2 (when any of the layers is precisely at the Dirac point, then the drag vanishes due to electron-hole symmetry). In the opposite limit of low temperature the drag is inversely proportional to both chemical potentials ρD∝ T2/(µ1µ2). In the mixed case where the chemical potentials of the two layers belong to the opposite limits µ1≪ T≪µ2 we find ρD∝ µ1/µ2. In the case of strongly doped graphene µ1(2)≫ v/d≫ T the drag coefficient acquires additional dependence on d and we recover the usual Fermi-liquid result if the screening length is smaller than d.