EFFECT OF MAGNETIC-FIELD AND TEMPERATURE ON THE VOLTAGE-CURRENT CHARACTERISTICS OF YBCO SUPERCONDUCTOR

Voltage-current characteristics of YBCO superconductor was studied und er magnetic field up to 0.4 T at different temperatures below T-c. The critical temperature decreases and the transition width broadens unde r magnetic field. V-I data below T-c were fitted to a power law expres sion V similar to I-beta(T,I-B) in which beta(T,B) is found to decreas e with increase of magnetic field and temperature, gradually approachi ng unity as T approaches T-c, being independent of magnetic field. Sim ilarly beta(T,B) approaches unity as magnetic field increases being in dependent of temperature.