Structural and magnetic properties and evidence of spin-glass behavior induced by Fe-doping in perovskite manganites B-site

AMn1-xFexO3 (A = La0.75Ca0.08Sr0.17 and x = 0-0.23) compounds, sintered at 700 deg. C, were characterized by X-ray diffraction (XRD) at room temperature. Rietveld refinement has shown that samples can be indexed in the orthorhombic (Pnma) structure for low Fe-content (x ≤ 0.046) and rhombohedral (R-3c) structure for high Fe-content (x ≥ 0.115). The transmission Moessbauer spectra have revealed the same isomer shift δ value assigned to Fe3+ ion for all compounds. The magnetization behavior and the Curie temperature TC have shown a large dependence on the fractional composition x. In fact, the M(T) curves have revealed the presence of a long-range ferromagnetic state below TC for compounds with x ≤ 0.115, and a spin-glass state (SGS) at low temperature for high Fe-content (x ≥ 0.177). Research Highlights: → La0.75Ca0.08Sr0.17Mn1-xFexO3 compounds undergo a transition ortho-rhombo at x=0.046. → On the rhombohedral phase, the magnetization is governed by the DE interaction → The magnetization undergoes a strong decrease at high x-values (x≥0.115). → Compounds show a strong AFM interaction with a spin-glass state at high Fe-content → Hysteresis loops, M(H) confirm this behavior.