Irradiation effect on the pinning potential of YBCO single crystal

The results of the magnetization measurements of single crystal of Yba2Cu3Oy with Tc equals 91K are adduced. The temperature, field and time dependencies of the remnant magnetization Mr(T, B, t) were obtained using VSM method for the temperature range from 4.2 K to 75 K for Hc configuration. The single crystal has been irradiated by the fast electrons with fluences up to 2 X 1018 cm-2. The relaxation of Mr(t) obeys to the logarithmic law for the time interval t equals 1 h for whole temperature range except the approximately 30-50 K interval for starting and irradiated states. After irradiation the Jc decease despite the flux creep reduction. The irradiation become less effective at high temperatures. The results are discussed in frame of conventional flux creep theory and of the interaction model of radiation defects with the background ones.