Paramagnetic Meissner Effect and Strong Time Dependence at High Fields in Melt-Textured High-T_C Superconductors

In this work we report on systematic field-cooled magnetization experiments in melt-textured YBa₂Cu₃O_7−δ samples containing Y211 precipitates. Magnetic fields up to 14 T were applied either parallel or perpendicular to the ab planes and a strong paramagnetic response related to the superconducting state was observed. This effect is known as paramagnetic Meissner effect (PME). The magnitude of the PME increases when the field is augmented. This effect shows a strong paramagnetic relaxation, such that the paramagnetic moment increases as a function of the time. The pinning by the Y211 particles plays a crucial role in the explanation of this effect and our results suggest that the pinning capacity can produce a strong flux compression into the sample, originating the PME and the strong time dependence.