Transmission across a bilayer graphene region

TL;DR

This paper investigates how gate voltages and domain walls affect electron transmission in bilayer graphene, revealing new ways to control conductance through topologically protected states and domain engineering.

Contribution

Develops a transfer matrix algorithm for ballistic transmission in bilayer graphene and uncovers the impact of domain walls and gate voltages on conductance behavior.

Findings

Conductance gap forms under finite gate voltage.

Domain walls host topologically protected in-gap states.

Transmission is highly sensitive to domain size.

Abstract

The transmission across a graphene bilayer region is calculated for two different types of connections to monolayer leads. A transfer matrix algorithm based on a tight binding model is developed to obtain the ballistic transmission beyond linear response. The two configurations are found to behave similarly when no gate voltage is applied. For a finite gate voltage, both develop a conductance gap characteristic of a biased bilayer, but only one shows a pronounced conductance step at the gap edge. A gate voltage domain wall applied to the bilayer region renders the conductance of the two configurations similar. For a microstructure consisting of equally spaced domain walls, we find a high sensitivity to the domain size. This is attributed to the presence of topologically protected in-gap states localized at domain walls, which hybridize as the domain size becomes of the order of their confining scale. Our results show that transmission through a bilayer region can be manipulated by a gate voltage in ways not previously anticipated.