2003/12/31 by C. C. Homes, S. V. Dordevic, D. A. Bonn +4
Earth and Planetary Sciences · Materials Science · Physics and Astronomy · #High-pressure geophysics and materials #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.71.184515
published as Phys. Rev. B 71, 184515 (2005). · Six pages with four figures and one table
arxiv created 2005/03/04 · openalex publication_date 2005/05/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The optical properties of single crystals of YBa2Cu3O6+x have been examined along the c axis above and below the critical temperature (Tc) for a wide range of oxygen dopings. The temperature dependence of the optically determined value of the dc conductivity (\ensuremathσdc) in the normal state suggests a crossover from incoherent (hopping-type) transport at lower oxygen dopings (x\ensuremath\lesssim0.9) to more coherent anisotropic three-dimensional behavior in the overdoped (x\ensuremath≈0.99) material at temperatures close to Tc. The assumption that superconductivity occurs along the c axis through the Josephson effect yields a scaling relation between the strength of the superconducting condensate (\ensuremathρs,c, a measure of the number of superconducting carriers), the critical temperature, and the normal-state c-axis value for \ensuremathσdc just above Tc: \ensuremathρs,c\ensuremath∝\ensuremathσdcTc. This scaling relation is observed along the c axis for all oxygen dopings, as well as several other cuprate materials. However, the Josephson coupling model does not require incoherent transport, so that the observed agreement with this model does not conflict with the normal-state results which point to coherent behavior at high oxygen dopings.