Chiral tunneling through generic one-dimensional potential barriers in bilayer graphene

TL;DR

This paper investigates chiral tunneling in bilayer graphene, revealing that perfect transmission at certain angles is not protected and can be suppressed, enabling potential new transistor designs without energy gap opening.

Contribution

It provides an explicit example showing that 'magic angles' with perfect transmission are not protected in bilayer graphene, allowing charge carrier locking without energy gap creation.

Findings

Magic angles with 100% transmission can be suppressed in bilayer graphene.

Asymmetric barriers significantly reduce transmission at all angles.

Potential for constructing graphene transistors without energy gap opening.

Abstract

We study tunneling of charge carriers in single- and bilayer graphene. We propose an explanation for non-zero "magic angles" with 100% transmission for the case of symmetric potential barrier, as well as for their almost-survival for slightly asymmetric barrier in the bilayer graphene known previously from numerical simulations. Most importantly, we demonstrate that these magic angles are not protected in the case of bilayer and give an explicit example of a barrier with very small electron transmission probability for any angles. This means that one can lock charge carriers by a p-n-p (or n-p-n) junction without opening energy gap. This creates new opportunities for the construction of graphene transistors.