Photoresponse of YBa2Cu3O7-delta films in the flux-creep regime

We have studied the effect of continuous illumination with visible light on the Aux motion in an epitaxial YBa2Cu3O7-x film over a wide range of tempe ratures. A ring-shaped sample was used to obtain voltage-current (V-I) char acteristics without applying electrical contacts. It is shown that the illu mination is substantially altering d In V/dl at low temperatures and low cu rrents. This effect is practically independent of the light intensity betwe en 5 and 100 klux and it remains appreciable even for illuminations as weak as 30 lux. The effect weakens with increasing temperature and vanishes at approximately 35 K.