| dc.description |
We present detailed measurements of the in-plane magnetoresistivity, , around the average superconducting transition in inhomogeneous (Y-123) and (Bi-2212) crystals with small -inhomogeneities non-uniformly distributed in the sample volume, associated with small oxygen-content inhomogeneities. In zero applied magnetic field, our results confirm the presence in these inhomogeneous Y-123 crystals of sharp resistivity peaks just above the average , and they also show for the first time the presence of similar anomalies in inhomogeneous Bi-2212 crystals. Our measurements for magnetic fields, H, applied perpendicularly or parallel to the (ab-) planes show that in these inhomogeneous superconductors the so-called magnetoresistivity excess, , is negative and very anisotropic near the average . By using two-dimensional electrical resistor networks, this behaviour is explained, simultaneously and consistently for both directions of the applied magnetic field, in terms of temperature dependent current density redistributions associated with the presence of non-uniformly distributed -inhomogeneities in the crystals. |
