Scaling behavior and mixed-state Hall effect in epitaxialHgBa2CaCu2O6+δsthin films

Abstract

We have measured the mixed-state Hall effect in superconducting ${\mathrm{HgBa}}_{2}$ ${\mathrm{CaCu}}_{2}$ ${\mathrm{O}}_{6+\mathrm{\ensuremath{\delta}}}$ thin films. We found that the Hall resistivity ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xy}}$ shows a double sign reversal in low fields, then shifts to positive without changing the general shape in higher fields. At the higher field region, the Hall conductivity ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xy}}$ is observed to be the sum of two terms, ${\mathrm{C}}_{1}$ /H and ${\mathrm{C}}_{2}$ H, where ${\mathrm{C}}_{1}$ and ${\mathrm{C}}_{2}$ are field independent. The scaling behavior between ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{xy}}$ and ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xx}}$ (longitudinal resistivity) shows a strong dependence on fields. The scaling exponent \ensuremath{\mathrm{B}} in ${\mathrm{\ensuremath{\rho}}}_{\mathrm{xy}}$ =A${\mathrm{\ensuremath{\rho}}}_{\mathrm{xx}}^{\mathrm{\ensuremath{\mathrm{B}}}g}$ increases from 1.5\ifmmode\pm\else\textpm\fi{}0.1 to 1.9\ifmmode\pm\else\textpm\fi{}0.1 as field increases from 1 to 5.5 T. The field dependence of tangent of the Hall angle is linear only in the flux-flow regime, different from Bi- and Tl-based cuprates.