Abstract
A vortex crossing a thin-film superconducting strip from one edge to the other, perpendicular to the bias current, is the dominant mechanism of dissipation for films of thickness on the order of the coherence length and of width much narrower than the Pearl length . At high bias currents the heat released by the crossing of a single vortex suffices to create a belt-like normal-state region across the strip, resulting in a detectable voltage pulse. Here is the critical current at which the energy barrier vanishes for a single vortex crossing. The belt forms along the vortex path and causes a transition of the entire strip into the normal state. We estimate to be roughly . Furthermore, we argue that such “hot” vortex crossings are the origin of dark counts in photon detectors, which operate in the regime of metastable superconductivity at currents between and . We estimate the rate of vortex crossings and compare it with recent experimental data for dark counts. For currents below , that is, in the stable superconducting but resistive regime, we estimate the amplitude and duration of voltage pulses induced by a single vortex crossing.
- Received 10 February 2011
DOI:https://doi.org/10.1103/PhysRevB.83.144526
©2011 American Physical Society