Flux-flow and phase-slip resistivity in two-phase polycrystalline Bi1.6Pb0.4Sr1.7Ca2Cu3Ox

Abstract

Using a contact‐less microwave technique, with an applied magnetic field varying to a maximum of 1.9 T, flux‐flow and phase‐slip resistivity are observed in a microsyntactically intergrown two‐phase superconductting sample of nominal composition Bi1.6Pb0.4Sr1.7Ca2 Cu3Ox. “Stretched exponential” response with β = 1/3 is observed in the phase‐slip resistivity. The onset temperature for the hightemperature phase is 106.5 K, while the lower‐temperature phase manifests itself at 71 K. Flux‐flow is observed superimposed on an isotropic background phase‐slip resistivity, and is locally maximal several degrees below each transition temperature. Flux‐flow resistivity, a consequence of the Lorentz force on a fluxoid, varies as sin2 (Ψ), where Ψ is the angle between the applied magnetic field and the r.f. current.