Observation of low-temperature magnetic ordering in mixed-phase Sr-Ca-Cu-O superconductors substituted by iron.

The series of unsubstituted Sr₂CaCu₂O₆ and iron-substituted Sr₂CaCu_2−xFe_xO₆ () materials were produced by a high-pressure synthesis route and characterized using X-ray diffraction and SQUID magnetometry. The change of contained phase ratio was found at different substituent concentrations in the samples synthesized under the same conditions: unexpected growth of 0201 and CuO phase with decrease of iron content was observed. Synthesis temperature-dependence of obtained phase fractions was found for the samples with . The superconductivity transition was found for all obtained samples and the highest critical temperature was around 103 K. From the SQUID measurements distortions of the magnetic susceptibility curves were found; these were explained by the magnetic ordering arising at low temperatures. This magnetic ordering was associated with the magnetic moment appearing in iron-doped 0201 phase. [ABSTRACT FROM AUTHOR]