Three-dimensional superconducting behavior and thermodynamic parameters of HgBa2Ca0.86Sr0.14Cu2O6- delta.

Abstract

This study measures the temperature dependence of reversible magnetization of grain-aligned HgBa{sub 2}Ca{sub 0.86}Sr{sub 0.14}Cu{sub 2}O{sub 6{minus}{delta}} high-{ital T}{sub {ital c}} superconductor with external magnetic fields parallel to the {ital c} axis. The magnetization is field independent at {ital T}{sup {asterisk}} = 114.5 K, which indicates strong thermal vortex fluctuations. From the vortex fluctuation model, the lower limit of coherence length along the {ital c} axis {xi}{sub {ital c}}(0){approx_equal} 2 and the anisotropy ratio {gamma}{le} 7.7 has been obtained, which implies that this sample is anisotropic three-dimensional (3D) superconductor as Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. These results are supported by good 3D scaling behavior of high-field magnetization around {ital T}{sub {ital c}}({ital H}) as a function of [{ital T}{minus}{ital T}{sub {ital c}}({ital H})]/({ital TH}){sup 2/3}. The thermodynamic critical field {ital H}{sub {ital c}}({ital T}) and the Ginzburg-Landau parameter {kappa} = 114.8 were extracted from the model of Hao {ital et} {ital al}. Also, the various thermodynamic parameters were obtained: the penetration depth {lambda}{sub {ital ab}}(0) = 1913 A, coherence length {xi}{sub {ital ab}}(0) = 13.9 A, and the zero temperature upper critical field {ital H}{sub {ital c}2}(0) = 170.4 T. {copyright} {ital 1996 The American Physical Society.}