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.

• Received 23 May 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.246801