Chiral states in bilayer graphene: magnetic field dependence and gap opening

TL;DR

This paper investigates chiral states in bilayer graphene at electrostatic kink profiles, examining their magnetic field response, the effect of potential smoothness, and the formation of minigaps due to kink-antikink overlaps.

Contribution

It provides new insights into the magnetic field effects, topological differences, and gap opening mechanisms of chiral states in bilayer graphene with electrostatic potential profiles.

Findings

Chiral states are weakly affected by magnetic fields due to strong confinement.

Smoother kink potentials create additional topologically distinct bound states.

Kink-antikink overlaps induce crossing and anti-crossing points, opening tunable minigaps.

Abstract

At the interface of electrostatic potential kink profiles one dimensional chiral states are found in bilayer graphene (BLG). Such structures can be created by applying an asymmetric potential to the upper and the lower layer of BLG. We found that: i) due to the strong confinement by the single kink profile the uni-directional states are only weakly affected by a magnetic field, ii) increasing the smoothness of the kink potential results in additional bound states which are topologically different from those chiral states, and iii) in the presence of a kink-antikink potential the overlap between the oppositely moving chiral states results in the appearance of crossing and anti-crossing points in the energy spectrum. This leads to the opening of tunable minigaps in the spectrum of the uni-directional topological states.