Metallic normal state of Y1Ba2Cu3O7−δ

Flux flow was studied over an entire temperature range down to T∼2%25 of Tc by using intense pulsed current densities to overcome flux-vortex pinning. The resistivity at high vortex velocities is proportional to B and roughly follows ρ∼ ρnB/Hc2, with a prefactor of order unity. Contrary to some speculation, ρn saturates to a finite residual value as T→0, indicating a metallic (ρ→finite) rather than insulating (ρ→∞) normal state, and the vortex dissipation continues to be conventional as T→0. © 2000 The American Physical Society.

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