Thermoremanence and Meissner effect in QMG and single-crystal YBCO

We compare flux pinning in a single crystal (twinned and detwinned) of YBa2Cu3O7-x (YBCO) with that in a quench-melt-growth (QMG) bulk YBCO sample using measurements of the thermoremanent magnetization and Meissner effect. For temperatures up to 50 K, there is practically no difference in the thermoremanent magnetization of the crystal in the twinned and detwinned states, while above 50 K the remanent flux in the twinned state is larger. The rate of decrease of thermoremanent magnetization with temperature is much lower for the OMG material. The OMG material has practically no Meissner effect over a wide range of applied fields, whereas a considerable difference in Meissner effect is seen between the twinned and detwinned states of the single crystal. (orig.)