Charge compensation and optimal stoichiometry in superconducting (Ca xLa 1-x)(Ba 1.75-xLa 0.25+x)Cu 3O y

Document Type

Article

Publication Date

10-31-2012

Abstract

The superconductive and magnetic properties of charge-compensated (Ca xLa 1-x)(Ba 1.75-xLa 0.25+x)Cu 3O 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 2Cu 3O y, cation doping of this unique tetragonal cuprate is constrained by compensating La substitution for Ba with Ca substitution for La, where for 0≤x≤0.5 local maxima in T C occur for y near 7.15. It is shown that optimum superconductivity occurs for 0.4≤x≤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, =7.1206 , and the distance between interacting layers, ζ=2.1297Å, are determined for x=0.45. The theoretical optimal T C0 -1ζ -1 of 82.3K is in excellent agreement with experiment (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 ±1.35 K). © 2012 American Physical Society.

Identifier

84869041400 (Scopus)

Publication Title

Physical Review B Condensed Matter and Materials Physics

External Full Text Location

https://doi.org/10.1103/PhysRevB.86.144533

e-ISSN

1550235X

ISSN

10980121

Issue

14

Volume

86

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