Chiral Tunnelling in Twisted Graphene Bilayer

TL;DR

This paper demonstrates how the chiral tunnelling probability in twisted graphene bilayer can be tuned from perfect transmission to reflection by adjusting barrier height or incident energy, revealing a new aspect of the Klein paradox.

Contribution

It introduces a novel form of Klein paradox in twisted graphene bilayer, showing tunable chiral tunnelling due to different quasiparticle chiralities.

Findings

Chiral tunnelling probability can be controlled in twisted graphene bilayer.

Tuning barrier height or incident energy affects tunnelling behavior.

Provides a method to modulate electronic properties of twisted graphene bilayer.

Abstract

The perfect transmission in graphene monolayer and the perfect reflection in Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in twisted graphene bilayer shows adjustable probability of chiral tunnelling for normal incidence: they can be changed from perfect tunnelling to partial/perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.