GIANT OUT-OF-PLANE MAGNETORESISTANCE IN BI-SR-CA-CU-O - A NEW DISSIPATION MECHANISM IN COPPER-OXIDE SUPERCONDUCTORS

We have measured the anisotropic magnetoresistivity tensor of single-crystal Bi2Sr2CaCu2O8 in the normal and mixed states. For magnetic fields applied perpendicular to the Cu-O (a-b) planes, the out-of-plane (c-axis) resistivity displays a huge magnetic enhancement, and a large apparent depression in the resistively measured transition temperature T(c)(c axis). No such depression is observed in T(c)(a-b plane). Although these results suggest a field-induced anisotropy in T(c), we propose an alternate model of novel Lorentz-force-independent fluctuation-induced dissipation in the mixed state. The model may also account for the anomalous anisotropic magnetoresistance seen in layered low-T(c) superconductors.