Anisotropy, pinning, and the mixed-state Hall effect

We have studied the mixed-state Hall effect of the high-{ital T}{sub {ital c}} superconductors Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4} (NCCO), Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (Tl2212), and YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO), and the isotropic low-{ital T}{sub {ital c}} superconductor amorphous Mo{sub 3}Si ({ital a}-Mo{sub 3}Si). We demonstrate the pinning independence of the Hall conductivity {sigma}{sub {ital xy}} and its consequent scaling in terms of the anisotropy of NCCO, Tl2212, and YBCO. In YBCO and {ital a}-Mo{sub 3}Si the Hall angle is enhanced as we reduce the effective pinning, yet {sigma}{sub {ital xy}} is unchanged. For all of these materials there is a vortex contribution {sigma}{sub {ital xy}}{similar_to}1/{ital H} at low fields while at high fields {sigma}{sub {ital xy}}{similar_to}{ital H}. 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.