Photoresponse of YBa2Cu3O7-x films in the flux creep regime

We have studied the effect of illumination on the flux creep in an epitaxia l YBa2Cu3O7-x film in a wide range of temperatures. A ring-shaped film was used to obtain voltage-current (V-I) characteristics without applying elect rical contacts. It is shown that illumination substantially alters the deri vative d ln Y/dI. The effect is particularly strong at low temperatures whe re d ln V/dI for the illuminated sample is almost an order of magnitude sma ller than that without illumination. A temperature increase weakens the eff ect which vanishes at approximately 35 K. The effect of illumination on d l n V/dI is practically independent of the light intensity between 5 and 100 klux and it is still remarkable even for illuminations as weak as 30 lux. ( C) 2000 Elsevier Science B.V. All rights reserved.