Manifestation of chiral tunneling at a tilted graphene pn junction

TL;DR

This paper demonstrates that chiral tunneling effects at tilted graphene pn junctions can be observed through junction resistance measurements, revealing the angular dependence of electron transmission and the influence of edge scattering.

Contribution

It provides a theoretical framework linking junction resistance to chiral tunneling at tilted graphene interfaces, supported by experimental evidence and analysis of edge effects.

Findings

Junction resistance increases with tilt angle, consistent with theory.

Edge scattering can reverse angular transmission effects, but is not dominant in experiments.

Chiral tunneling effects are observable and significant in tilted graphene pn junctions.

Abstract

Electrons in graphene follow unconventional trajectories at PN junctions, driven by their pseudospintronic degree of freedom. Significant is the prominent angular dependence of transmission, capturing the chiral nature of the electrons and culminating in unit transmission at normal incidence (Klein tunneling). We theoretically show that such chiral tunneling can be directly observed from the junction resistance of a tilted interface probed with separate split gates. The junction resistance is shown to increase with tilt in agreement with recent experimental evidence. The tilt dependence arises because of the misalignment between modal density and the anisotropic transmission lobe oriented perpendicular to the tilt. A critical determinant is the presence of edge scattering events that can completely reverse the angle-dependence. The absence of such reversals in the experiments indicates that these edge effects are not overwhelmingly deleterious, making the premise of transport governed by electron `optics' in graphene an exciting possibility.