Direct evidence of Klein-antiKlein tunneling of graphitic electrons in a Corbino geometry

TL;DR

This paper provides direct experimental evidence of Klein and anti-Klein tunneling phenomena in graphene p-n junctions using a Corbino geometry, revealing unique angular transmission features and their dependence on doping and magnetic fields.

Contribution

It demonstrates the first direct signatures of Klein and anti-Klein tunneling in a Corbino geometry, with detailed experimental data matching theoretical predictions.

Findings

Angular Brewster angles minimize head-on transmission in bilayer graphene.

Magnetoconductance maxima shift to higher fields with increased doping.

Experimental results align well with numerical simulations and analytical models.

Abstract

Transport measurement of electron optics in monolayer graphene p-n junction devices has been traditionally studied with negative refraction and chiral transmission experiments in Hallbar magnetic focusing set-ups. We show direct signatures of Klein (monolayer) and anti-Klein (bilayer) tunneling with a circular 'edgeless' Corbino geometry made out of gated graphene p-n junctions. Noticeable in particular is the appearance of angular sweet spots (Brewster angles) in the magnetoconductance data of bilayer graphene, which minimizes head-on transmission, contrary to conventional Fresnel optics or monolayer graphene which shows instead a sharpened collimation of transmission paths. The local maxima on the bilayer magnetoconductance plots migrate to higher fields with increasing doping density. These experimental results are in good agreement with detailed numerical simulations and analytical predictions.