THE EFFECT OF SAMPLE SHAPE ON THE MEASUREMENT OF INTERGRAIN CURRENTS IN YBACUO

The critical current density in sintered YBCO was found to vary by up to a factor of three in sintered material as the angle between the sample and the applied field was varied. Currents were always perpendicular to the field and the effect is attributed to the demagnetising effect of the sample. By defining H as the external field equilibrium with a flux density B the authors use classical electromagnetism to calculate the demagnetising effect. When Jc is plotted as a function of H or B in the material, rather than the external field, the anisotropy disappears. © 1990 IOP Publishing Ltd.