Pinning and the intrinsic magnetic-field dependence of the mixed-state Hall conductivity in amorphous and

We have investigated the pinning and magnetic-field dependence of the mixed-state Hall conductivity (Formula presented) in thin films of two superconductors, amorphous (Formula presented) and (Formula presented) The effects of pinning were varied by measuring at different current densities (Formula presented). In both superconductors, (Formula presented) is independent of (Formula presented) (and, therefore, pinning) in support of theory. The magnetic-field dependence of (Formula presented) at large and small magnetic fields strongly supports calculations based on time-dependent Ginzburg-Landau theory. In addition, we find sample inhomogeneities can cause a fictitious current dependence of (Formula presented) We argue this explains the conflicting reports of the pinning and magnetic-field dependence of (Formula presented) found in the literature. © 1997 The American Physical Society.