Field Dependence of Current Density in Strong Pinning YBCO Single Crystals with Different Microstructure

摘要

YBa_2Cu_3O_(7-δ) single crystals with high critical current densities and different micro-structure of the twin pattern were studied by means of torque magnetometry. Pinning contributions due to random point pinning and to con-elated disorder as well as the influence of thermal oscillations of the fluxlines within the pinning barriers arc discussed. Different collective pinning regimes of the fluxline lattice which are characterized by different power law behaviour of the form j(B_z) ∝ B_z~(p-1) could be identified.