Crossover from a three-dimensional to purely two-dimensional vortex-glass transition in deoxygenated YBa2Cu3O7-delta thin films

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    LATTICE-MELTING TRANSITION;    SOLID PHASE-TRANSITION;    THERMAL FLUCTUATIONS;    II SUPERCONDUCTORS;    BOSON LOCALIZATION;    UNIVERSALITY;    RESISTIVITY;    TRANSPORT;    DISORDER;   

DOI  :  10.1103/PhysRevB.60.15423

来源: SCIE

【 摘 要 】

Current-voltage (I-V) characteristics were used to investigate the response of the vortex-glass(VG) phase transition in high-quality epitaxial YBa2Cu3O7-delta films in magnetic fields up to 7 T. We show that varying the oxygen content, the scaling analysis reveals a crossover from three-dimensional (3D) to a pure 2D VG transition with T-g=0. At small oxygen deficiencies (7-delta=6.75), the rho-j curves scale according to the 3D VG model, which cannot be distinguished from a Bose-glass model from a scaling analysis with the magnetic field applied parallel to the c axis. At a lower oxygen content (7-delta=6.48), the VG phase transition behaves analogous to the highly anisotropic Bi2Sr2CaCu2O8 samples, showing a quasi-2D VG transition. For further deoxygenated samples (7-delta=6.4), the result is consistent with a pure 2D vortex-glass model similar to that observed in the even more anisotropic Tl2Ba2CaCu2O8 thin films. The estimated value of the anisotropy in high-quality oxygen-depleted samples is comparable to that of the highly anisotropic superconductors. [S0163-1829(99)05246-7].

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