Complex Magnetic Behavior in the PrSr3(Fe1–xCox)3O10−δ n = 3 Ruddlesden–Popper-Type Solid Solution with High Valent Cobalt and Iron

Abstract

Ruddlesden–Popper-type solid solutions PrSr3(Fe1–xCox)3O10−δ (x ≤ 0.60, δ < 0.10; space group I4/mmm) were synthesized, and their structural, electrical, and magnetic properties were investigated as a function of temperature (mostly subambient) by neutron powder diffraction (NPD), Mössbauer spectroscopy, electrical-conductivity, and magnetization measurements. For the parent phase (x = 0.00), cooling leads to a partial charge disproportionation of Fe4+, formation of an imperfect or short-range magnetic order (evidenced in Mössbauer spectra and discernible in NPD as weak and broad magnetic reflections), and a resistivity increase by orders of magnitude upon a succession of conduction mechanisms. Substitution of Fe by Co introduces ferromagnetic interactions that dramatically increase the conductivity. The random Co distribution then results in a local magnetic frustration and possibly also in the formation of nanoscopic magnetic clusters evidenced by anomalous hysteresis loops in M(H) curves as well as by frequency-dependent ac susceptibilities.