Charge compensation and optimal stoichiometry in superconducting (Ca${}_x$La${}_{1-x}$)(Ba${}_{1.75-x}$La${}_{0.25+x}$)Cu${}_3$O${}_y$

Abstract

The superconductive and magnetic properties of charge$-$compensated (Ca${}_x$La${}_{1-x}$)(Ba${}_{1.75-x}$La${}_{0.25+x}$)Cu${}_3$O${}_y$ (normally denoted as CLBLCO) are considered through quantitative examination of data for electrical resistivity, magnetic susceptibility, transition width, muon$-$spin rotation, x$-$ray absorption, and crystal structure. A derivative of LaBa${}_2$Cu${}_3$O${}_y$, cation doping of this unique tetragonal cuprate is constrained by compensating La substitution for Ba with Ca substitution for La, where for 0 {\le} x {\le} 0.5 local maxima in T${}_C$ occur for y near 7.15. It is shown that optimum superconductivity occurs for 0.4 {\le} x {\le} 0.5, that the superconductivity and magnetism observed are nonsymbiotic phenomena, and that charge$-$compensated doping leaves the carrier density in the cuprate planes nearly invariant with x, implying that only a small fraction of superconducting condensate resides therein. Applying a model of electronic interactions between physically separated charges in adjacent layers, the mean in-plane spacing between interacting charges, {\ell} = 7.1206 Å, and the distance between interacting layers, ζ = 2.1297 Å, are determined for x = 0.45. The theoretical optimal T${}_{C0}$ {\propto} {\ell}${}^{-1}$ζ${}^{-1}$ of 82.3 K is in excellent agreement with experiment ({\approx} 80.5 K), bringing the number of compounds for which T${}_{C0}$ is accurately predicted to 37 from six different superconductor families (overall accuracy of {\pm}1.35 K).

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Cited by in corpus (5)

• Comment on "Superconductivity in electron-doped layered TiNCl with variable interlayer coupling"
• Superconducting interaction charge in thallium-based high-Tc cuprates: Roles of cation oxidation state and electronegativity
• On the isotope effect in compressed superconducting H${}_{\text{3}}$S and D${}_{\text{3}}$S
• Charge compensation and optimal stoichiometry in superconducting (Ca${}_x$La${}_{1-x}$)(Ba${}_{1.75-x}$La${}_{0.25+x}$)Cu${}_3$O${}_y$
• High-$T_{\text{C}}$ superconductivity in Cs${}_3$C${}_{60}$ compounds governed by local Cs-C${}_{60}$ Coulomb interactions