Interplay of the Aharonov-Bohm effect and Klein tunneling in graphene

TL;DR

This study numerically explores how Klein tunneling influences Aharonov-Bohm oscillations in graphene rings, revealing that interface smoothness significantly affects transmission and oscillation behavior.

Contribution

It demonstrates the impact of interface smoothness on Klein tunneling effects in graphene rings and their influence on quantum interference patterns.

Findings

Sharp junctions show symmetric amplitude profiles around charge neutrality.

Smooth junctions suppress Aharonov-Bohm oscillations in Klein tunneling.

Transmission depends strongly on the smoothness of $pn$-interfaces.

Abstract

We numerically investigate the effect of Klein tunneling on the Aharonov-Bohm oscillations in graphene rings using a tight-binding model with nearest-neighbor couplings. In order to introduce Klein tunneling into the system, we apply an electrostatic potential to one of the arms of the ring, such that this arm together with the two adjacent leads form either a $nn'n$- or $npn$-junction ($n,n'$: conduction band transport, $p$: valence band transport). The former case corresponds to normal tunneling and the latter case to Klein tunneling. We find that the transmission properties strongly depend on the smoothness of the $pn$-interfaces. In particular, for sharp junctions the amplitude profile is symmetric around the charge neutrality point in the gated arm, whereas for smooth junctions the Aharonov-Bohm oscillations are strongly suppressed in the Klein tunneling as compared to the normal tunneling regime.