In-plane dissipation maxima and vortex-line distortions in the resistive transitions of oxygen-doped Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} single crystals

Measurements of the in-plane resistive transition of ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathrm{\delta }}$ single crystals in perpendicular magnetic fields reveal that in oxygen-reduced samples a giant resistance maximum evolves with field. This is not seen in oxygenated samples with similar metallic normal resistivities. As the peak resistivity may exceed the normal resistivity, it cannot arise from ordinary vortex-motion dissipation. We propose a model where the excess resistance results from nonrigid vortex motion coupling the out-of-plane dissipation to the in-plane resistance at temperatures where pinning effects are negligible.