Vortex pinning and the decay of persistent currents in unsaturated superfluid helium films

Publisher Website
Google Scholar
Abstract
We investigate the role played by vortex pinning in modifying the predictions of the Kosterlitz-Thouless theory for thin helium films. We extend the analysis of Huberman, Myerson, and Doniach and of Ambegaokar et al. to include vortex pinning. We find that the presence of surface roughness can give rise to pinning sites and that the presence of the sites can modify the predictions of the above authors for the decay of persistent currents. We test these modifications by fitting our formulas to the data of Ekholm and Hallock, and find that the fits are much improved over the fits done without taking into account the effects of pinning.