Conductance of electrostatic wire junctions in bilayer graphene

TL;DR

This paper investigates the conductance properties of electrostatic wire junctions in bilayer graphene, revealing a conductance quench near quantization and uncovering a chiral edge mode, with implications for topological electronic states.

Contribution

It demonstrates the existence of a chiral edge mode in trivial wires and analyzes conductance behaviors in trivial-topological junctions, providing new insights into topological effects in bilayer graphene.

Findings

Conductance near 2e^2/h in trivial-topological junctions.

Discovery of a chiral edge mode in trivial wires.

Periodic Fano-like conductance resonances in double junctions.

Abstract

The conductance of electrostatic wire junctions in bilayer graphene, classified as trivial-trivial or trivial-topological regarding the confinement character on each junction side, is calculated. The topological side always corresponds to a kink-antikink system, as required for a proper connection with a trivial side. We report a conductance quench of the trivial-topological junction, with a conductance {\it near} quantization to $4e^2/h$, which is only half of the maximum value allowed by the Chern number of a kink-antikink system. The analysis allowed us to uncover the existence of a chiral edge mode in the trivial wire under quite general conditions. A double junction, trivial-topological-trivial, displays periodic Fano-like conductance resonances (dips or peaks) induced by the created topological loop.