Multiband tunneling in trilayer graphene

TL;DR

This paper investigates the tunneling properties of trilayer graphene with different stacking orders, revealing how gating and stacking influence Klein tunneling, interband scattering, and band gap opening.

Contribution

It provides a comparative analysis of tunneling phenomena in ABC and ABA trilayer graphene, highlighting the effects of gating and stacking symmetry on electron transport.

Findings

Klein paradox occurs at normal incidence in ABC TLG with single gate.

Double gating induces intermode scattering and resonances in ABA TLG.

Double gating opens a band gap in ABC TLG, suppressing Klein tunneling.

Abstract

The electronic tunneling properties of the two stable forms of trilayer graphene (TLG), rhombohedral ABC and Bernal ABA, are examined for pn and pnp junctions as realized by using a single gate (SG) or a double gate (DG). For the rhombohedral form, due to the chirality of the electrons, the Klein paradox is found at normal incidence for SG devices while at high energy interband scattering between additional propagation modes can occur. The electrons in Bernal ABA TLG can have a monolayer- or bilayer-like character when incident on a SG device. Using a DG however both propagation modes will couple by breaking the mirror symmetry of the system which induces intermode scattering and resonances that depend on the width of the DG pnp junction. For ABC TLG the DG opens up a band gap which suppresses Klein tunneling. The DG induces also an unexpected asymmetry in the tunneling angle for single valley electrons.