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

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 $\hat{I}½>1$ and a strongly suppressed conductance for $\hat{I}½<1$. A transition between the two behaviors is found near $\hat{I}½\approx 1$. The zero-bias anomaly (ZBA) line shapes find explanation in Luttinger liquid models of tunneling between quantum Hall edge states. The ZBA for $\hat{I}½<1$ occurs from strong backscattering induced by suppression of quasiparticle tunneling between the edge channels for the $n=0$ Landau levels. The ZBA for $\hat{I}½>1$ arises from weak tunneling of quasiparticles between the $n=1$ edge channels.

version with edits for clarity