FINE-STRUCTURE IN A HIGH-RESOLUTION VORTEX DISSIPATION STUDY OF YBA2CU3O7-DELTA

Using high-Q double-torsional silicon oscillators vibrating at extreme ly low amplitude, numerous fine minima and maxima have been observed i n the dissipation vs temperature data for certain characteristic field s perpendicular to the c axis in single crystal YBa2Cu3O7-delta. These features are mirrored in the frequency shift vs temperature data. An intrinsic pinning model in which the dissipation minima correspond to conditions of commensureability between the interlayer spacing and bot h the coherence length and Abrikosov lattice spacing is suggested to e xplain these features.