Magnetic Pinning Effect In High-Tc Superconductor Gdbacuo

The samples of GdBa2Cu3O7-delta and YBa2Cu3O7-delta were prepared by standard solid state reaction. Their pinning potentials were deduced from flux-creep studies. Despite the similarity of their microstructures, the pinning potentials of GdBaCuO are higher than that of YBCO at different applied magnetic field. In this paper we present our experimental results and discuss the physical mechanism of the differences based on the interaction between the isolated magnetic moments of gadolinium ions and flux lines in the sample. Theoretically, we argue that this interaction may be a new pinning mechanism in high T(c) superconductors with magnetic rare earth ions.