Magneto-optical study of grain boundaries, in terfacesand grain boundary networks in YBaCuO

摘要

Using quantitative magneto-optics and an inv ersion scheme of Biot-Sav art's law the local current carrying capability of various types of grain boundaries (GB's) and interfaces in YBaCuO thin films and bulk material was inv estigated. In all GB's and interfaces a spatial variation of the local critical current density j_c was observed which, however, has different reasons, such as microstructural inhomogencities, magnetic field dependence of j_c and size effects in extended GB's and networks of lo wangle grain boundaries (LAGB's).