Interplay between magnetism and superconductivity in the FeYSr2Cu2Oy iron substituted cuprate

We want to address the problem of a possible coexistence of superconductivity and magnetism in the FeSr2YCu2Oy cuprate by means of a combined ZF/TF-muSR study. This compound presents a laminar ordering of copper and iron along the crystallographic c axis, allowing the study of the iron oxidation state effect in the superconducting and magnetic properties of this material. We have observed a progressive evolution from a magnetic parent compound at low doping levels to a bulk superconducting phase after ozone treatment. We aim here to characterize by ZF-muSR the temperature and doping dependence of the magnetic interactions, in order to resolve whether these interactions precede or compete with superconductivity. For this purpose, the real superconducting volume fractions are to be also determined by a TF-muSR measurement of the magnetic penetration depth.