Ac magnetic susceptibility and microwave absorption study of GdBa2−xLaxCu3O7 high temperature superconductors

Abstract The GdBa 2− x La x Cu 3 O 7 series has been prepared and studied by XRD, magnetic a.c. susceptibility and microwave absorption. The transition temperature T c , as a function of the doping level, shows a nonlinear variation in two steps indicating a hole filling phenomenon joined to an oxygen reorganization between a and b axis. Microwave absorption study confirms the decrease of the dephasing field H d of the Josephson junctions as increasing the La ratios. The irreversible domain studied by a.c. susceptibility is reduced and the Ba substitution by La does not constitute a defect for pinning the vortices into the structure.