Physica C: Superconductivity and its applications

Scaling behavior at the vortex glass transition

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We find scaling behavior of the linear ac-impedence consistent with a phasetransition from a normal or vortex fluid state into a superconducting or vortex glass state in measurements on cuprate YBa2Cu3O7 superconducting thin films in strong fields (0.55 T). At the vortex glass transition temperature, Tg=86.1 K, as determined from dc IV-curves we find scaling with frequency of the impedance amplitude, | Z | ≈ ω 0.83, and a frequency independent phase, ø=74°. In addition a critical slowing down of the vortex dynamics consistent with a diverging correlation time is observed as Tg is approached, τ≈(T-Tg)-5.8. © 1991.