FLUX-FLOW HALL-EFFECT IN SUPERCONDUCTING TL2BA2CACU2O8 FILMS

In both high-T(c) and low-T(c) superconductors, the Hall effect in the mixed state often shows a sign reversal below T(c) that contradicts standard theories for flux-vortex motion. We have measured the mixed-state Hall effect in high-quality superconducting films of Tl2Ba2CaCu2O8, and find that the Hall angle alpha below T(c) consists of two components: A field-independent component exhibits a complicated temperature dependence, including a sign change near T(c), while a second component with very weak temperature dependence is linear in field and resembles the normal-state Hall angle. The field independence of the sign-reversing component is evidence for vortex motion, and can be understood in terms of simple drag forces acting on vortices.