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Anisotropic coherence lengths of YBa 2 Cu 3 O 7‐δ from specific heat measurements near T c
Author(s) -
Schnelle W.,
Ernst P.,
Wohlleben D.
Publication year - 1993
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.19935050202
Subject(s) - anisotropy , condensed matter physics , physics , coherence length , gaussian , coherence (philosophical gambling strategy) , crossover , specific heat , superconductivity , optics , quantum mechanics , artificial intelligence , computer science
We present a detailed analysis of high resolution measurements of the specific heat anomalies at the T c of three YBa 2 Cu 3 O 7‐δ ‐samples. The anomalies can be described by the sum of a mean field (MF) step and a contribution from gaussian fluctuations of the order parameter. These fluctuations are threedimensional (3D) near T c and show a crossover to 2D‐behaviour some K away from T c . By means of a Lawrence‐Doniach type description of the fluctuations we estimate the anisotropic coherence lengths ξ and ξ⊥. The values are consistent with data of the fluctuation contribution to the susceptibility above T c . We give data for Δ C MF and discuss the relevance of critical fluctuations. The influence of the oxygen content δ on the broadening and splitting of the transition is shown.