Conductivity fluctuation in the high temperature superconductor with planar weight disparity Y0.5Sm0.5Ba2Cu3O7−δ

Abstract

AbstractThe synthesis of the Y0.5Sm0.5Ba2Cu3O7–δ superconducting material by the standard solid state reaction is reported. DC resistivity measurements reveal the improvement of the critical temperature (Tc) when substitution of exact 50‐50 mix of Yttrium and Samarium is performed. A bulk Tc = 101 K was determined by the criterion of the maximum in the temperature derivative of electrical resistivity. Structure characterization by means the x‐ray diffraction technique shows the crystalline appropriated distribution of Yttrium and Samarium to create substantial planar weight disparity (PWD) in alternating layers. This PWD increases Tc in copper‐oxide superconductors. In order to examine the effect of PWD on the pairing mechanism close to Tc, conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. We found the occurrence of Gaussian and genuinely critical fluctuations. Our results are in agreement with reports on YBa2Cu3O7–δ, but an enhancement of the Gaussian fluctuation regimes was experimentally detected as a result of the PWD. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov‐Larkin theory. The genuinely critical exponent is interpreted by the 3D‐XY model as corresponding with the dynamical universality class of the E‐model. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)