Investigation of structural, electrical, and magnetic properties of La-doped Nd2FeMnO6 double perovskites

The Nd2-xLaxFeMnO6 double perovskite oxides, with compositions x = 0.0, 0.3, 0.6, and 0.9, were synthesized using a conventional solid-state reaction method in polycrystalline form, at 1100 C & ring; in air. The structural and vibrational analyses of synthesized samples were investigated through X-ray diffraction (XRD) and Raman spectroscopy. Rietveld refinement confirmed that all the samples exhibited typical double perovskite structures with Pbnm space group, belonging to the orthorhombic symmetry. X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of a + 3 oxidation state for Nd, La, Fe, and, Mn ions. The Raman spectra were deconvoluted using the Gaussian function revealing that for x = 0.0 and 0.6, nine first-order Raman modes, whereas ten modes were observed for x = 0.3 and 0.9. Further structural analysis was conducted using the Vesta and Gfourier programs. Morphological studies demonstrated well-formed grain and grain boundaries within the materials. Elemental confirmation (Nd, La, Fe, Mn, and O) was carried out via energy-dispersive X-ray spectroscopy (EDX). The electrical properties of all the samples were analyzed by investigating their dielectric behavior with varying frequencies and at fixed temperatures and vice versa. The ac conductivity of all the prepared samples was analyzed at room temperature with varying frequency. AC magnetization measurements at room temperature confirmed the dominant exchange interaction between Fe3+ and Mn3+ ions over Nd3+/La3+, indicating a complex interplay between antiferromagnetism (AFM) and ferromagnetic interactions (FM). Consequently, all the samples exhibited AFM behavior with weak FM interaction. The ZFC and FC curves reveal spin glass behavior for all the prepared samples. Thus, phase pure double perovskites, prepared at high temperatures, were comprehensively characterized for structural, electrical, and magnetic properties.