Quantitative description of Josephson-like tunneling in $\nu_T=1$ quantum Hall bilayers

TL;DR

This paper investigates Josephson-like tunneling in quantum Hall bilayers at total filling factor 1, showing experimental agreement with a fluctuation-based theory and exploring effects of tunneling amplitude and critical currents.

Contribution

It provides a quantitative theory matching experimental tunneling conductance data and discusses effects of large tunneling amplitudes and critical currents in quantum Hall bilayers.

Findings

Tunneling conductance peak height and width depend on sample area, tunneling amplitude, magnetic field, and temperature.

Experimental data aligns with a phenomenological fluctuation theory.

Qualitative changes occur at larger tunneling amplitudes, explaining observed critical currents.

Abstract

At total filling factor $\nu_T=1$, interlayer phase coherence in quantum Hall bilayers can result in a tunneling anomaly resembling the Josephson effect in the presence of strong fluctuations. The most robust experimental signature of this effect is a strong enhancement of the tunneling conductance at small voltages. The height and width of the conductance peak depend strongly on the area and tunneling amplitude of the samples, applied parallel magnetic field and temperature. We find that the tunneling experiments are in quantitative agreement with a theory which treats fluctuations due to meron excitations phenomenologically and takes tunneling into account perturbatively. We also discuss the qualitative changes caused by larger tunneling amplitudes, and provide a possible explanation for recently observed critical currents in counterflow geometry.