Phase diagram of a current-carrying superconducting film in the absence of a magnetic field

Abstract

A phase diagram of the current states of superconducting films is produced on the basis of an experimental study of the resistive transitions induced by the transport current. It is found that a comparatively narrow film of width w<5λ⊥ (λ⊥ is the penetration depth of the magnetic field) never enters a vortex state, but undergoes a direct transition from the purely superconducting state into a resistive state with phase-slip centers as soon as the current exceeds the critical Ginzburg-Landau current IcGL. The Meissner current state of films with intermediate widths 5λ⊥(T)<w<10λ⊥(T) transforms, when I>0.8IcGL, into a vortex resistive state which exists at currents 0.8IcGL<I<Im, where the upper critical current is in good agreement with the theory. The vortex state of wide films with w>10λ⊥(T) exists for currents IcAL<U<Im, where IcAL is the current at the transition into the vortex state calculated for the limiting case w⪢λ⊥. When I>Im, films with widths w>5λ⊥(T) enter a vortex-free resistive state with phase-slip lines.