Phase‐glass scaling near the coherence transition in granular HoBa₂Cu₃O_7–δ superconducting thin films

Abstract

Systematic measurements of electrical magnetoconductivity near the coherence transition of granular HoBa 2 Cu 3 O 7 -δ thin films are reported. Experiments performed in magnetic fields ranging from 0 to 2500 Oe reveal that close to the coherence transition temperature T c0 (H), the correlation length scales as a power law of temperature with a thermal-dependent critical exponent, ν . In low external fields the corresponding value of ν is consistent with the two-dimensional phase-glass model, which is in the same dynamical universality class of the so-called vortex-glass model. At applied fields H > 1000 Oe, the vortex dynamics becomes stronger and the coherence transition is not observed.