INFLUENCE OF VISIBLE-LIGHT ON FLUX-CREEP IN HTS FILMS

We present an experimental study of the flux creep rate in YBCO film a t low temperatures. It is shown that the flux creep can be described i n terms of quantum tunneling of vortices up to temperatures of 10-15 K . We have investigated also the influence of a weak illumination on a flux creep rate. It is shown that a visible light with intensity as we ak as 1 mW/cm(2) drastically changes the flax creep rate at liquid hel ium temperatures. We propose a simple model to explain this extreme se nsitivity of the flux creep to a weak illumination.