Interaction dominated transport and Coulomb drag in bilayer graphene

TL;DR

This paper explores interaction effects in bilayer graphene, revealing a constant minimal conductivity at low temperatures and detailed behavior of Coulomb drag across different regimes, highlighting differences from monolayer graphene.

Contribution

It provides a comprehensive analysis of transport and Coulomb drag in bilayer graphene, including the temperature dependence of conductivity and the interplay of interactions and disorder near charge neutrality.

Findings

Minimal conductivity approaches a constant as T→0 with √T correction.

Coulomb drag in BLG resembles Fermi liquids away from charge neutrality.

No saturation of drag with distance for realistic parameters.

Abstract

We investigate interaction effects in transport phenomena in bilayer graphene (BLG). For the minimal conductivity in pristine BLG, we find that the conductivity assumes a constant value in the limit $T\to 0$, with the first correction being $\propto \sqrt{T}$. This has to be contrasted from the standard $1/T^2$ in Fermi liquids (neglecting additional logarithms and above all disorder). We furthermore study the Coulomb drag resistivity between two BLGs in the whole range from deep within the Fermi liquid regime all the way to the charge neutrality (CN) point. We find that in the Fermi liquid regime drag behaves very similarly to drag in a standard two-dimensional electron gas. In contrast to monolayer graphene, we find no saturation of drag as a function of the distance $d$ for realistic parameters. In the vicinity of CN, we find an interesting interplay between interaction effects and disorder, like in the case of monolayer graphene. Here the drag resistivity strongly depends upon the ratio of the corresponding scattering times.