We have measured the transport critical current densityJ_cof sintered YBa₂Cu₃O₇, in various applied fields up to 185 Oe at 77 K. We find a sharp decay ofJ_cwith magnetic field. We show that this sharp decay is consistent with the low field hysteresis results of Groveret al. We argue that the observed field dependence is not caused by intragranular weak links.

We have studied the variation of low field magnetization hysteresis in YBa₂Cu₃O₇ as a function of the maximum magnetic field applied during a hysteresis cycle (1 G<H_max<7.3 G) and also as a function of temperature (77 K<T<95 K). The remnant magnetization is studied as a function ofH_max andT and the measured dependences are explained using the extended critical state model. The potential of this technique as a contactless method of probing the temperature dependence ofJ_c is discussed.