Helical States in Curved Bilayer Graphene

TL;DR

This paper investigates helical states in curved bilayer graphene quantum wires, demonstrating their controllability via gate voltage and their potential to host Majorana fermions when coupled with superconductors.

Contribution

It introduces a method to generate and control helical states in bilayer graphene using curvature, magnetic fields, and electrostatic confinement, enabling Majorana fermions.

Findings

Helical states can be induced in bilayer graphene quantum wires.

Gate voltage modulates the localization length of helical states.

Proximity to an s-wave superconductor can produce Majorana fermions.

Abstract

We study spin effects of quantum wires formed in bilayer graphene by electrostatic confinement. With a proper choice of the confinement direction, we show that in the presence of magnetic field, spin-orbit interaction induced by curvature, and intervalley scattering, bound states emerge that are helical. The localization length of these helical states can be modulated by the gate voltage which enables the control of the tunnel coupling between two parallel wires. Allowing for proximity effect via an s-wave superconductor, we show that the helical modes give rise to Majorana fermions in bilayer graphene.