Magnetic field and current distributions in melt-textured YBa2Cu3O7-x withan artificial grain boundary

Using a magneto-optical (MO) technique, magnetic field distributions have b een measured in a melt-textured YBa2Cu3O7-x bulk superconductor. joined to form an artificial grain boundary (GB), in an external magnetic field perpe ndicular to the sample surface, The magnetic field at a weak section of the GB shows different values between the field increasing up to 150mT and dec reasing down to 0T after zero-field-cooling. Namely, the magnetic field in increasing field is higher than that in decreasing field, even in the same external field. This result supports a model in which such differences in m agnetic field at the weak-link GB give rise to the hysteresis behavior in t he field dependence of transport critical current density in polycrystallin e samples, The field distributions across a well-joined region of the CB be have similarly to the adjoining bulk material and this result indicates the possibility of creating useful artifacts provided that the strongly couple d sections can be reproduced on a larger scale.