Insulating behavior in metallic bilayer graphene: Interplay between density inhomogeneity and temperature

TL;DR

This paper explores how inhomogeneous charge puddles and temperature influence the insulating behavior in bilayer graphene, revealing coexistence of metallic and insulating transport due to local activation gaps.

Contribution

It introduces an analytic statistical theory that accounts for the non-mean-field effects of inhomogeneity on transport in bilayer graphene.

Findings

Puddles induce insulating behavior even away from charge neutrality.

Coexistence of metallic and insulating transport observed.

Local activation gaps explain temperature-dependent conductivity.

Abstract

We investigate bilayer graphene transport in the presence of electron-hole puddles induced by long-range charged impurities in the environment. We explain the insulating behavior observed in the temperature dependent conductivity of low mobility bilayer graphene using an analytic statistical theory taking into account the non-mean-field nature of transport in the highly inhomogeneous density and potential landscape. We find that the puddles can induce, even far from the charge neutrality point, a coexisting metallic and insulating transport behavior due to the random local activation gap in the system.