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

Abstract

At total filling factor $ν_T=1$, 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.