A self-consistent study of vortex pinning/dynamics in single-crystal BSCCO-2212 platelet and prism specimen geometry

Predictions of a treatment, which includes specimen shape, vortex pinning a nd surface effects, are self-consistently fitted to experimental BSCCO-2212 magnetisation data for platelet and 'prism' single-crystal specimen geomet ries. The platelet specimen manifests, in accordance with theoretical expec tation, a sharp dimensional cross-over transition from 30 to quasi-2D (arro whead) behaviour at about the predicted cross-over field B-2D in the regime T less than or equal to 40 K. The magnetic hysteresis in this specimen is shown to be predominantly due to the shape/geometry effect and, respectivel y, to 3D small-bundle and large-bundle collective pinning behaviour above a nd below this transition. The prism specimen shows a 'diffuse' cross-over t ransition, and the hysteresis is shown to be dominated by surface vortex pi nning and a 'distributed surface-barrier' mechanism. (C) 2000 Elsevier Scie nce B,V. All rights reserved.