Universal vortex-state Hall conductivity of YBa2Cu3O7 single crystals with differing correlated disorder

The vortex-state Hall conductivity (σxy) of YBa2Cu3O7 single crystals in the anomalous-sign-reversal region is found to be independent of the density and orientation of the correlated disorder. After the anisotropic-to-isotropic scaling transformation is carried out, a universal scaled Hall conductivity σ-tildexy is obtained as a function of the reduced temperature (T/Tc) and scaled magnetic field strength (H-tilde) for five samples with different densities and orientation of controlled defects. The transport scattering times (τ), derived from applying the model given by Feigel'man et al (Feigel'man M V, Geshkenbein V B, Larkin A I and Vinokur V M 1995 Pis. Zh. Eksp. Teor. Fiz. 62 811 (Engl. Transl. 1995 JETP Lett. 62 835)) to the universal Hall conductivity σ-tilde(T/Tc, H-tilde), are consistent in magnitude with those derived from other measurements for quasiparticle scattering, and are much smaller than the thermal relaxation time of vortex displacement and than the vortex-defect interaction time. Our experimental results and analyses therefore suggest that the anomalous sign reversal in the vortex-state Hall conductivity is associated with the intrinsic properties of type-II superconductors, rather than extrinsic disorder effects. (author)