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

The vortex-state Hall conductivity (sigma(xy)) 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 <(sigma)over tilde (xy)> is obtained as a function of the reduced temperature (T/T-c) and scaled magnetic field strength ((H) over tilde) for five samples with different densities and orientation of controlled defects. The transport scattering times (tau), derived from applying the model given by Feigel'man er 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 <(sigma)over tilde>(T/T-c, (H) over 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.