# Tuning anti-Klein to Klein tunneling in bilayer graphene

## TL;DR

This paper demonstrates that in gapped bilayer graphene, the Berry phase and tunneling behavior can be tuned to mimic single-layer graphene's Klein tunneling, revealing a controllable transition between anti-Klein and Klein tunneling regimes.

## Contribution

It shows how to control the Berry phase and tunneling in bilayer graphene, enabling the transition from anti-Klein to Klein tunneling by tuning the Fermi energy.

## Key findings

- Berry phase can be tuned from 2π to 0.68π in gapped bilayer graphene.
- Transition from anti-Klein to Klein tunneling observed at normal incidence.
- Berry phase of π corresponds to single-layer graphene behavior.

## Abstract

We show that in gapped bilayer graphene, quasiparticle tunneling and the corresponding Berry phase can be controlled such that it exhibits features of single layer graphene such as Klein tunneling. The Berry phase is detected by a high-quality Fabry-P\'{e}rot interferometer based on bilayer graphene. By raising the Fermi energy of the charge carriers, we find that the Berry phase can be continuously tuned from $2\pi$ down to $0.68\pi$ in gapped bilayer graphene, in contrast to the constant Berry phase of $2\pi$ in pristine bilayer graphene. Particularly, we observe a Berry phase of $\pi$, the standard value for single layer graphene. As the Berry phase decreases, the corresponding transmission probability of charge carriers at normal incidence clearly demonstrates a transition from anti-Klein tunneling to nearly perfect Klein tunneling.