Size effects in the nonlinear resistance and flux creep in a virtual Berezinskii-Kosterlitz-Thouless state of superconducting films

Abstract

We show that the size effects radically affect the electric field-current (E-I) relation of superconducting films. We calculate E(J) due to thermally-activated hopping of single vortices driven by current I across the film in a magnetic field H, taking into account interaction of free vortices with their antivortex images and peaks in the Meissner currents at the film edges. Unbinding of virtual vortex-antivortex pairs not only mimics the transport uniform BKT behavior, it can dominate the observed E(J) and result in the field-dependent ohmic resistance at small I. We show that E(I) can be tuned by changing the film geometry and propose experimental tests of this theory.