Angular dependence of magnetoresistivity and Hall effect in a YBa2Cu3Ox thin film

In this paper we present the magnetoresistivity and the Hall effect measurements we have performed on a YBCO epitaxial film varying the angle curly theta between the external magnetic field and the ab-planes. The measurements are analyzed and discussed in terms of the scaling approach proposed by Blatter and co-workers [13,20]. We concentrate our attention on an apparent failure of the scaling. This behaviour allows one to distinguish two regions where dissipation is dominated, respectively, by thermal activation of the vortices pinned to extrinsic pinning centers and by the motion of free vortices and quasi-particles. The same identification of the dissipation regimes is obtained from the analysis of the Hall conductivity data. When the applied magnetic field direction is tilted towards the nb-planes, the structure of the vortices changes, fitting the layered structure of the lattice. The resistivity in this region is analyzed in the light of the passage from tilted to undulated vortex lattice.