Tuning the superconducting state in the magneticMoSr2YCu2O8−δmaterials

Abstract

The properties of ${\mathrm{MoSr}}_{2}{\mathrm{YCu}}_{2}{\mathrm{O}}_{8\ensuremath{-}\ensuremath{\delta}}$ materials are found to systematically change with the oxygen concentration determined by the sintering and annealing conditions. The as-prepared (asp) sample is antiferromagnetically ordered at 16 K. The magnetic features are related to the ${\mathrm{Mo}}^{5+}$ sublattice. Annealing under an oxygen atmosphere induces superconductivity (SC) in the Cu-O planes, and the ${\mathrm{T}}_{\mathrm{C}}$ and the shielding fraction values obtained depend strongly on the oxygen concentration. Annealing the asp material at $1030\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ under ambient oxygen atmosphere yields ${\mathrm{T}}_{\mathrm{C}}$ of 18 K, whereas further annealing at $650\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ under 92 atm. of oxygen, shifts ${\mathrm{T}}_{\mathrm{C}}$ to 32 K. The antiferromagnetic ordering, which coexists with SC state through effectively decoupled subsystems, is not affected by the presence or absence of the SC state. In all samples studied, ${\mathrm{T}}_{\mathrm{N}}<{\mathrm{T}}_{\mathrm{C}}.$ This behavior resembles most of the inter-metallic magneto-superconductors, but is in sharp contrast to the iso-structural ${\mathrm{RuSr}}_{2}{\mathrm{GdCu}}_{2}{\mathrm{O}}_{8}$ system where ${\mathrm{T}}_{\mathrm{N}}>{\mathrm{T}}_{\mathrm{C}}.$