2 research outputs found
Coulomb drag in graphene near the Dirac point
We study Coulomb drag in double-layer graphene near the Dirac point. A
particular emphasis is put on the case of clean graphene, with transport
properties dominated by the electron-electron interaction. Using the quantum
kinetic equation framework, we show that the drag becomes -independent in
the clean limit, , where is temperature and
impurity scattering rate. For stronger disorder (or lower temperature), , where is the interaction strength, the kinetic
equation agrees with the leading-order () perturbative result. At
still lower temperatures, (diffusive regime) this contribution
gets suppressed, while the next-order () contribution becomes
important; it yields a peak centered at the Dirac point with a magnitude that
grows with lowering .Comment: 3 figures, with expanded Supplemental Material attached as an
appendi
Plasmons in layered structures including graphene
We investigate the optical properties of layered structures with graphene at
the interface for arbitrary linear polarization at finite temperature including
full retardation by working in the Weyl gauge. As a special case, we obtain the
full response and the related dielectric function of a layered structure with
two interfaces. We apply our results to discuss the longitudinal plasmon
spectrum of several single and double layer devices such as systems with finite
and zero electronic densities. We further show that a nonhomogeneous dielectric
background can shift the relative weight of the in-phase and out-of-phase mode
and discuss how the plasmonic mode of the upper layer can be tuned into an
acoustic mode with specific sound velocity.Comment: 18 pages, 6 figure