PINNING, ANISOTROPY, AND THE HALL-EFFECT IN SUPERCONDUCTORS

We have studied the Hall effect in the mixed state of amorphous Mo3Si, an isotropic low-T-c superconductor, and the high-T-c superconductors Tl2Ba2CaCu2O8 (Tl2212), Nd1.85Ce0.15CuO4 (NCCO), and YBa2Cu3O7 (YBCO) , which have differing amounts of anisotropy. All of these superconduc tors display a sign reversal below T-c. In Mo3Si we reduce the effecti ve pinning with high current and find the Hall angle increases, yet th e Hall conductivity sigma(xy) is unchanged. We also demonstrate the pi nning independence of the Hall conductivity and its consequent scaling in terms of the anisotropy of Tl2212, NCCO, and YBCO. For all of thes e materials there is a vortex contribution sigma(xy)(v) similar to 1/B at low fields, while at high fields sigma(xy) similar to B.