Repetition of the disordered pattern in successive solidifications of vortex matter observed by Bitter decoration

Repeated images of the vortex structure in YBa2Cu3O7-delta Single crystals have been obtained, using the Bitter technique. By removing the iron dots b etween each decoration experiment, it is possible to image the vortices in different cooldown runs done under the same field and temperature condition s. The images show that these different realizations of a disordered vortex state found in twinned crystals are very similar at long range and differ only in small-scale detail. This is unusual behavior in glassy systems, whe re expectations are that successive configurations will differ over many sc ales. In contrast, ordered vortex crystals in clean samples can form with d ifferent orientations in different runs, therefore differing at long ranges . Double-sided decorations have been performed in twinned samples, and the correlation between images in both sides of the sample is similar in magnit ude but slightly different qualitatively than that found in successive deco rations.