Gate tunable quantum transport in double layer graphene heterostructures

Motivated by the recently observed highly resistive state in double layer graphene heterostructures [1] we consider a system of two layers of graphene, ``studied'' and ``control,'' separated by an insulating layer. We theoretically analyze the effect of additional screening provided by Dirac electrons in the ``control'' graphene layer on the transport characteristics of the ``studied'' graphene layer. We find that in a typical device geometry fabricated on top of SiO2 substrate [1] the suppression of charge inhomogeneity is less efficient than initially expected and is limited by about a factor of 2. We also analyze the effect of additional screening on the quantum correction to the conductivity of the ``studied'' layer in this system in the metallic regime. We find that ``control'' layer screening is very efficient at suppressing electron-electron interactions in the ``studied'' layer which results in improved coherence and a novel gate tunable quantum correction to conductivity. The results of this work are summarized in [2].\\[4pt] [1] L. A. Ponomarenko et. al. Nat. Phys. 7, 958 (2011).\\[0pt] [2] K. Kechedzhi, E. H. Hwang, and S. Das Sarma Phys. Rev. B 86, 165442 (2012).