Decoupling of the CuO2 plane and superconductivity in Cu0.5Tl0.5Ba2(Ca2-ySry)Cu3O10-δ(y=0-0.4) samples

Cu0.5Tl0.5Ba2(Ca2-ySry)Cu3O10-delta(y = 0-0.4) samples have been synthesized at normal pressure at 860 degrees C. The main objectives of these experiments to study the role of inter-plane decoupling in suppressing the superconductivity of high temperature superconductors (HTSC). These samples have shown orthorhombic crystal structure and the c-axis length increases with increased Sr-doping. All the samples have shown metallic variations of resistivity (rho) from room temperature down to the onset of superconductivity. The magnitude of the superconductivity is suppressed and the apical oxygen modes are hardened with Sr-doping. These studies have shown that Sr-doping promotes de coupling of conducting CuO2 planes which suppress the superconducting properties of final compound. The excess conductivity analyses have shown increases in the width of two-dimensional (2D) Lawrence-Doniach (LD) regime with Sr-doping. The coherence length along the c-axis xi(c(0)), the inter-layer coupling J, the phase relaxation time of the carriers tau(phi) and the Fermi velocity v(F) of superconductor carriers is suppressed. The underlying reason for the suppression of superconductor properties is the decrease in the density of carriers in the superconductor planes. However, the values of B-c0(T), B-c1(T) and J(c)(0) have been found to increase with the increased Sr-doping, which is suggested to be originating from the enhancement in the flux pinning character which is induced by Sr-doping. The values of magnetic field penetration depth lambda(p.d) and the Ginzburg-Landau (GL) parameter kappa decrease with Sr-doping and it is also suggested to be originating from the increase of flux pinning character of the samples with Sr-doping.