MAGNETIC HYSTERESIS IN HIGH-TEMPERATURE CUPRATES

Hysteretic behaviour of high-T-c superconducting ceramics at weak and moderate magnetic fields is studied theoretically and numerically in t erms of the two-level magnetic system, consisting of superconducting d omains (grains) and weak link network forming a quasi-continuous super conducting intergranular medium, both treated as type II superconducto rs. We present a new concept of magnetization of a granular supercondu ctor. Influence of the geometry of both the grains and the sample is i nvolved, and relevance of the model to experimental measurement of mag netization as well as transport critical current is studied. (C) 1998 Elsevier Science B.V. All rights reserved.