THE EFFECT OF RANDOM DISORDER ON INTRINSIC PINNING IN YBA(2)CN(3)O(7-X) SINGLE-CRYSTALS

The presence of lock-in oscillations in the magnetic hysteresis loops of YBa2Cu3O7-x (YBCO) single crystals, for applied fields parallel to the layered structure, is a unique tool in the study of intrinsic pinn ing. By using the lock-in oscillations we can obtain important conclus ions on the role of the point disorder in the CuO2 planes. We gain a r are insight of how point disorder competes with the layered structure in pinning the vortices. We also present the first experimental result s of the temperature dependence of the critical current in the quasi-2 D regime, which clearly deviates from the existing theoretical predict ions.