By combining micro-Hall probe and magneto-optical imaging techniques we have been able to examine vortex avalanches at different locations of the ridgelike magnetic topography of superconducting niobium samples as the external field is slowly increased. The avalanche size distributions are shown to be power laws for two decades with very similar critical exponents at all locations, thus demonstrating a remarkable robustness in the details of the flux penetration dynamics.

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We have fabricated highly resistive materials PrBa 2 (Cu 1-x M x ) 3 O 7 (M=Al, Ga, x = 0.20) by doping metals Ga and Al on PrBa 2 Cu 3 O 7 (PBCO). X-ray data indicated no significant second phases in substituting Cu by Al or Ga up to 20%.The electrical resistivity of these materials were three to four orders in magnitude higher than PBCO at 200K, which may give an effective potential barrier to YBCO in high T c S-I-S Josephson junction. Epitaxial thin films of these materials were grown using KrF excimer laser on LAO (110) single crystal substrates. X-ray diffraction (XRD) and atomic force microscopy (AFM) were deployed to study the crystal orientation, epitaxy and roughness of the single crystal thin films. Micro Raman spectroscopy was carried out to investigate the dopant site in PBCO.