THE CURRENT DEPENDENCE OF THE EFFECTIVE PINNING POTENTIAL IN HIGH-TC SUPERCONDUCTORS

Within the framework of thermally activated flux creep, we propose a method that directly combines the magnetic relaxation curves or the transport current-voltage (I- V) characteristics in the whole temperature range, and yields the current dependence of the effective pinning potential U(eff)(j). This method allows us to extend the time range of the magnetic relaxation or the voltage range of the I-V characteristics. A successful application of this method to the high-T(c) superconductors demonstrates that the fundamental mechanism of dissipation in these materials is thermally activated flux creep.