Zero-Bias Anomalies in Narrow Tunnel Junctions in the Quantum Hall Regime

TL;DR

This paper investigates zero-bias anomalies in narrow tunnel junctions within the quantum Hall regime, revealing different conductance behaviors for filling factors above and below one, explained by Luttinger liquid models.

Contribution

It provides experimental evidence of zero-bias anomalies in quantum Hall edge states and explains their line shapes using Luttinger liquid theory, highlighting the transition near filling factor one.

Findings

Enhanced conductance for filling factors > 1

Suppressed conductance for filling factors < 1

Transition near filling factor 1

Abstract

We report on the study of cleaved-edge-overgrown line junctions with a serendipitously created narrow opening in an otherwise thin, precise line barrier. Two sets of zero-bias anomalies are observed with an enhanced conductance for filling factors $\nu > 1$ and a strongly suppressed conductance for $\nu < 1$. A transition between the two behaviors is found near $\nu \approx 1$. The zero-bias anomaly (ZBA) line shapes find explanation in Luttinger liquid models of tunneling between quantum Hall edge states. The ZBA for $\nu < 1$ occurs from strong backscattering induced by suppression of quasiparticle tunneling between the edge channels for the $n = 0$ Landau levels. The ZBA for $\nu > 1$ arises from weak tunneling of quasiparticles between the $n = 1$ edge channels.