Propriedades Magnéticas do Supercondutor YBa2Cu3O7-δ na forma de filmes finos e monodomínios texturizados

Abstract

An experimental study of magnetic properties of the YBa2Cu3O7-δ superconductor grown in the form of thin films and in melt-textured monodomain is presented in this work. The thin films were provided by the Institut de Ciència de Materials de Barcelona (ICMAB), located in the Universitat Autònoma de Barcelona, Spain. The melt-textured sample used in this study was provided by the Departamento de Ciencia de los Materiales e Ingenieria Metalúrgica, located in Universitat de Barcelona, Spain, through collaboration with the company Diopma, also Spain. The magnetization measurements were performed according to the ZFC and FCC magnetization procedures. Magnetic fields from zero up to 50 kOe were applied parallel to the ab planes and along the c-axis. In some cases, the FCC magnetization results reveal the occurrence of the paramagnetic Meissner effect (PME), whose properties depend on the magnitude of the applied field. At low magnetic fields the effect reduces in intensity as magnetic field is increased. Moreover, in high fields the magnitude of paramagnetic moment increases when the field is augmented. The effect was observed both in the thin films and the melt-textured sample. We discuss our results in terms of models based on ideas from flux magnetic compression inside the superconductor. We investigated the behavior of the magnetic irreversibility line in the three samples, with the magnetic field applied along the ab planes and the c-axis. In all cases, the irreversible magnetic behavior is described by the power law predicted in accordance with the giant flux creep model for flux dynamics inside a superconductor. The comparative results lead us to believe that melt-textured sample exhibit better vortex pinning potential than thin films.