TEMPERATURE-DEPENDENCE OF THE PINNING POTENTIAL IN THE HIGH-TEMPERATURE SUPERCONDUCTOR Y1BA2CU3O7-X

Combining the results of magnetization decay and microwave absorption experiments the logarithmic flux decay in twinned YBaCuO crystals was studied over a wide temperature range (Kelvin = 0.1 to 0.8) under conditions of small applied external fields (B = 2.4 mT). The resulting quasi exponential temperature dependence of the pinning potential can be modelled satisfactorily by assuming a structural limitation for the shielding current, resulting from S-N-S barriers. The temperature dependence in the crystalline material is similar to j(cr) (Kelvin) observed for epitaxic YBaCuO films, and leads to an estimate of the barrier width of the order of 10 nm.