Structural, chemical, and magnetic properties of Mn-substituted La0.6Ga0.4Fe1−xMnxO3 perovskites

Abstract

Mn-substituted La0.6Ga0.4Fe1-xMnxO3 ceramics were synthesized by solid-state reaction and investigated using Rietveld-refined x-ray diffraction, x-ray photoelectron spectroscopy (XPS) and room-temperature magnetometry. All compositions crystallize in the orthorhombic Pnma structure, while Mn incorporation induces anisotropic lattice variations and local modifications of the (Fe, Mn)–O octahedral environment. XPS analysis reveals composition-dependent changes in near-surface Fe, Mn and O chemical environments associated with mixed-valence-like contributions and oxygen-related surface components. Magnetic measurements show weak ferromagnetic-like behavior superimposed on an antiferromagnetic background, with a decrease in saturation magnetization from 5.79 to 3.33 emu g−1 and composition-dependent horizontal and vertical hysteresis-loop shifts. The magnetic response is discussed within a hierarchical structural framework consisting of micrometer-scale sintered grains containing smaller coherent diffraction domains (approximately 117–221 nm) previously reported for the same composition series. This multiscale organization, together with Mn-induced lattice distortion and near-surface chemical heterogeneity, provides a basis for understanding the evolution of magnetic interactions in the substituted perovskite ceramics. The results highlight the importance of correlating coherent-domain structure, local chemical environments and magnetic properties in functional oxide materials.