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

Abstract

[Formula: see text]–[Formula: see text] samples have been synthesized at normal pressure at 860[Formula: see text]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 [Formula: see text]-axis length increases with increased Sr-doping. All the samples have shown metallic variations of resistivity [Formula: see text] 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 decoupling of conducting [Formula: see text] 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 [Formula: see text]-axis [Formula: see text], the inter-layer coupling [Formula: see text], the phase relaxation time of the carriers [Formula: see text] and the Fermi velocity [Formula: see text] 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 [Formula: see text], [Formula: see text] and [Formula: see text] 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 [Formula: see text] and the Ginzburg–Landau (GL) parameter [Formula: see text] 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.