INFLUENCE OF WEAK VISIBLE-LIGHT ON FLUX-CREEP IN YBCO FILM AT LOW-TEMPERATURES

We present an experimental study of flux creep in YBCO film. A ring-sh aped film was used to directly obtain voltage-current characteristics of the film in a flux creep regime. It is shown that the flux creep ca n be described in terms of quantum tunneling of vortices up to tempera tures of 10-15 K. We have also investigated the influence of weak illu mination on flux creep rate. It is shown that visible light with inten sity less than 1 mW/cm(2) drastically accelerates the flux creep at li quid helium temperatures. The influence of light is completely differe nt to that caused by the temperature rise. We propose a simple qualita tive model to explain the high sensitivity of the flux creep to weak i llumination.