Mixed-state Hall-effect studies in high-Tc-superconducting (YBa2Cu3O7-δ)n/(PrBa2Cu3O7-δ)m superlattices

The mixed-state Hall conductivity behavior has been studied systematically on a series of superconducting (YBa2Cu3O7)n/(PrBa2Cu3O7)8 (here n=3,8,16,24,45,60) superlattices in three magnetic fields with H??c axis and H?J. It was found that the Hall sign anomaly diminishes and even disappears with the decreasing of the YBCO layer thickness, i.e., the increase of the anisotropy parameter ?, and the decrease of the pinning strength. The scaling relationship between the Hall resistivity ?xy and the longitudinal resistivity ?xx, i.e., ?xy??xx? holds for all of the samples with various ?. This indicates that the anomalous Hall sign reversal is independent of the scaling law between ?xy and ?xx. The present work supports the Wang, Dong, and Ting theory which suggested that the mixed-state Hall sign anomaly originated from the backflow current due to the pinning force and the thermal fluctuations. © 1996 The American Physical Society