Paramagnetic moments in YBa₂Cu₃O_7-δ nanocomposite films

We report on magnetization studies in YBa₂Cu₃O_7-δ thin films with dispersed Ba₂YTaO₆ nanoparticles. The magnetization measurements were made using a superconducting quantum interference device (SQUID) and a vibrating sample magnetometer (VSM). Magnetic moments were measured as functions temperature using zero-field cooling (ZFC) and field-cooled (FC) prescriptions for magnetic fields up to 10 T applied parallel and perpendicular to the ab planes. A paramagnetic response related to the superconducting state was observed during the FC experiments. This effect, known as paramagnetic Meissner effect (PME), apparently increases when the magnetic field is increased. We discuss our PME results in terms of the strong pinning scenario modulated by Ba₂YTaO₆ nanoparticles dispersed into the superconducting matrix.