Fluctuation conductivity along the c-axis and parallel to the ab-planes in melt-textured YBa2Cu3O7−δ samples doped with Y211 phase

• Published in: Physica. B, Condensed matter Vol. 404; no. 19; pp. 3106 - 3108
• Main Authors: Teixeira Dias, Fábio, Vieira, Valdemar das Neves, Pureur, Paulo, Rodrigues, Pedro, Obradors, Xavier
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier B.V 15-10-2009; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Fluctuation conductivity; Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.); Granular, melt-textured, amorphous and composite superconductors; Inhomogeneous superconductors and superconducting systems; Physics; Scaling regimes; Superconductivity; Fluctuation conductivity; Superconductivity; Scaling regimes; Fluctuations; Electrical conductivity; Superconducting transitions; Doping; Magnetic field effects; Order parameters; XY model; Low field; Phenomenological model; Scaling laws; High-Tc superconductors; Melt texturing; Barium Copper Yttrium Oxides Mixed
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2009.07.058

We report measurements of in-plane and out-of-plane fluctuation conductivity under low applied magnetic fields up to 500Oe in two melt-textured YBa2Cu3O7−δ (YBCO) samples. 3D-Gaussian and genuine critical 3D-XY-E fluctuation regimes were identified in the conductivity parallel to the ab plane. In addition, a regime beyond 3D-XY was observed in the immediate vicinity of the superconducting transition of the in-plane fluctuation conductivity. The 3D-XY-E scaling was also identified in the fluctuation conductivity along the c-axis in the sample with smaller content of the Y2BaCuO5 (Y211) phase. This result indicates that the superconducting state in YBCO has a three-dimensional character, in contradiction to some studies suggesting that critical phenomenology is fundamentally distinct in orientations parallel or perpendicular to the Cu–O2 planes of the high-temperature superconductors. However, the results suggests the presence of a sub-dominant order-parameter component in YBCO that has an appreciable projection along the c-axis.