Dual-gated bilayer graphene with layer mismatch

Abstract

One of the key features of graphene is the chirality of the electrons originating from the lattice symmetry. Conservation of the chirality leads to Klein and anti-Klein tunneling in graphene and AB-stacked bilayer graphene, respectively. Introduction of an external perturbation (electric field, strain, twist, layer mismatch, etc.) can change the chirality and therefore significantly modify the quantum transport. We explore the tunneling in AB-stacked bilayer graphene in the presence of an in-plane pseudomagnetic field (IPMF) and an out-of-plane electric field (OEF). Employing a low-energy effective model, we study the energy spectrum, chirality, and wave functions to evaluate the transmission and conductance in an $n\text{\ensuremath{-}}p\text{\ensuremath{-}}n$ junction. We demonstrate that the IPMF and OEF together induce an indirect band gap. The IMPF induces a layer polarization of propagating states (enhanced in the presence of the OEF) with the layer symmetry broken locally in a single valley but preserved globally. While the effect of the IPMF is negligible in the ballistic transport regime at the neutrality point, the OEF suppresses the ballistic transport (partially recovered in the presence of the IPMF). In the diffusive transport regime, the IPMF amplifies the Fabry-P\'erot resonances, thus modifying the conductance, while the OEF induces an out-of-plane chirality component that enables Klein resonances.