Low field hysteresis and loss in sintered samples of YBa 2Cu 3O 7-x

Abstract

We have measured the ac susceptibility and the low field (H < 100 Oe) magnetization of sintered samples of YBa 2Cu 3O 7-x. A hysteresis loop is found to be superimposed on a linear reversible behavior. The temperature dependence of the width of this loop can be described by [1 - (T/T c) 2], where T c is the same as for the bulk material. We argue that the hysteresis is due to narrow, but superconducting, connections between the grains of the sintered sample. We also find indirectly that a single crystal does not show low field hysteresis.