Flux Creep and Pinning Potential in Melt-grown YBCO

At temperature 77K and magnetic field 1-5 T, measurement of voltage-current curve in the melt-grown YBCO has been performed. The characteristics of the curves were found to be of an exponential form for E < lμV/cm. The behaviour is consistent with the flux creep model. The flux pinning potential energy has been calculated.