Nonlocal Resistivity in the Fluctuation Region of Thin Superconducting Film

The nonlocal resistivity in fluctuation region of thin superconducting films is observed and investigated. It is supposed that the observed non-local resistivity is caused by a difference of distribution laws of normal and superconducting current density. The measurements show that the nonlocal resistivity is suppressed in low magnetic field. The obtained results are interpreted as the absence of a coherence in the fluctuation state called " vortex liquid ". 74.60.Ge Investigation of the fluctuation phenomena remains one of the most popular theme of the superconductor physics. A big number of works concerning this theme has appeared in last ten years after the discovery of high-temperature superconductors, HTSC, but many important questions do not have definitive answers for the present. Now it is obvious that the transition into the Abrikosov state does not occur in the second critical field, H c2. But it is not clear what is the fluctuation state existing above and below H c2 which is called often as " vortex liquid ". It is difficult to imagine this fluctuation state now. The widespread naive notion about the vortex liquid as a liquid of the vortexes gives rise to doubt. This notion supposes that the vortexes exist in the vortex liquid. Consequently a transition connected with a vortex disappearance must be above the vortex lattice melting. But no experiment evidence of such transition has been observed for the present. Moreover the experiment results above vortex lattice melting are described the same fluctuation theoretical dependence above and below H c2 [1,2]. Therefore the denomination " vortex liquid " is no quite good. This denomination supposes that the vortex is a particle. But the vortex is not so much a particle as a singularity. Therefore it may be that the " vortex lattice melting " is no a disappearance of a order in a particle distribution but a disappearance a medium in which the singularities exist. Now not only the adequate image of the vortex liquid is absent but also a universally recognized approach to the description of this state is absent. A great number of different theoretical approaches is consequence of a little number of experimental data. Therefore the experimental investigation is timely there. One of the most important question is a question about coherence in the " vortex 1