Perfect transmission at oblique incidence by trigonal warping in graphene P-N junctions

TL;DR

This paper introduces an analytical mode-matching technique for graphene P-N junctions that reveals perfect electron transmission at oblique angles due to trigonal warping, differing from the normal incidence Klein tunneling.

Contribution

It presents a new analytical method combining simplicity and accuracy for tight-binding models and uncovers a novel perfect transmission phenomenon at oblique angles.

Findings

Disappearance of Klein tunneling at normal incidence.

Emergence of perfect transmission at oblique angles.

Effect is due to conservation of generalized pseudospin.

Abstract

We develop an analytical mode-matching technique for the tight-binding model to describe electron transport across graphene P-N junctions. This method shares the simplicity of the conventional mode-matching technique for the low-energy continuum model and the accuracy of the tight-binding model over a wide range of energies. It further reveals an interesting phenomenon on a sharp P-N junction: the disappearance of the well-known Klein tunneling (i.e., perfect transmission) at normal incidence and the appearance of perfect transmission at oblique incidence due to trigonal warping at energies beyond the linear Dirac regime. We show that this phenomenon arises from the conservation of a generalized pseudospin in the tight-binding model. We expect this effect to be experimentally observable in graphene and other Dirac fermions systems, such as the surface of three-dimensional topological insulators.