Anisotropy, pinning, and the mixed-state Hall effect

We have studied the mixed-state Hall effect of the high-Tc superconductors Nd1.85Ce0.15CuO4 (NCCO), Tl2Ba2CaCu2O8 (Tl2212), and YBa2Cu3O7 (YBCO), and the isotropic low-Tc superconductor amorphous Mo3Si (a-Mo3Si). We demonstrate the pinning independence of the Hall conductivity xy and its consequent scaling in terms of the anisotropy of NCCO, Tl2212, and YBCO. In YBCO and a-Mo3Si the Hall angle is enhanced as we reduce the effective pinning, yet xy is unchanged. For all of these materials there is a vortex contribution xy1/H at low fields while at high fields xyH. These results provide evidence that beneath the effects of pinning and anisotropy a relatively simple and universal behavior of the mixed-state Hall effect exists.