Three-dimensional superconducting behavior and thermodynamic parameters ofHgBa2Ca0.86

Abstract

This study measures the temperature dependence of reversible magnetization of grain-aligned HgBa 2 Ca 0.86 Sr 0.14 Cu 2 O 6Ϫ␦ high-T c superconductor with external magnetic fields parallel to the c axis. The magnetization is field independent at T* ϭ 114.5 K, which indicates strong thermal vortex fluctuations. From the vortex fluctuation model, the lower limit of coherence length along the c axis c (0)Ӎ 2 and the anisotropy ratio ␥р 7.7 has been obtained, which implies that this sample is anisotropic three-dimensional ͑3D͒ superconductor as Y 1 Ba 2 Cu 3 O 7Ϫ␦ . These results are supported by good 3D scaling behavior of high-field magnetization around T c (H) as a function of ͓TϪT c (H)͔/(TH) 2/3 . The thermodynamic critical field H c (T) and the Ginzburg-Landau parameter ϭ 114.8 were extracted from the model of Hao et al. Also, the various thermodynamic parameters were obtained: the penetration depth ab ͑0͒ ϭ 1913 Å, coherence length ab ͑0͒ ϭ 13.9 Å, and the zero temperature upper critical field H c2 ͑0͒ ϭ 170.4 T.

Scaling of the Equilibrium Magnetization in the Mixed State of Type-II Superconductors

“…This type of κ(T ) behavior resulted in practically all published analyses, in which the Hao-Clem model was applied to experimental magnetization data. [24][25][26][27][28][29][30][31][32][33][34][35][36] The standard explanation is that because of thermal fluctuations of vortices, which are not accounted for by the model, this approach is inapplicable at higher temperatures. Considering the data presented in Fig.…”

Comment on “Enhanced two-dimensional properties of the four-layered cuprate high-TcsuperconductorTlBa2Ca3Landau1, Ott2 2005Phys. Rev. B6050View full textAdd to dashboardCite

“…1, 4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 However, we recently demonstrated that the fluctuation induced corrections to the magnetization remain negligibly small up to temperatures very close to T c , 21 thus suggesting a more general inadequacy of the model. While on previous occasions we could only speculate on the origin of the failure of the model, we are now able to show that most likely it is the insufficient accuracy in the calculation of M (H, κ) using the Hao-Clem model.…”

“…1, 4,5,6,7,8,9,10,11,12,13,14,15,16,17,18 Instead of rising some doubts in the validity of the model, this feature was taken as evidence of a particularly strong influence of thermal fluctuations on the sample magnetization at temperatures still well below T c .…”

Angle dependence of the Hall effect inHgBa2CaCu2O6thin films

“…2 For the compounds of the Hg-Ba-Ca-Cu-O family, that have an intermediate anisotropy 6 between YBCO and BSCCO-2212, many fewer investigations have been performed regarding the angle-dependence of the transport properties. The resistivity of (Hg,Re)Ba 2 CaCu 2 O 6 was recently 7 studied under variation of the magnetic field orientation with respect to the c-axis, and the dependence of the depinning field on the tilt angle was inferred.…”