The impact of 50% combined Fe and Mn ions at the B-sites on the structural, optical, magnetic and dielectric properties of double perovskite Nd₂FeMnO₆

Novel functional materials with competing degrees of freedom have potential breakthrough in the research and development of memory devices and spintronics. In this perspective, double perovskite provides flexible selection of cations and invoke keen interest for technological applications. In this report rare earth oxide material, Nd₂FeMnO₆ double perovskite have been investigated. Nd₂FeMnO₆ double perovskite was conventionally synthesized via solid state reaction method followed by sintering at high temperature of 1200 °C. Rietveld refined X-ray diffractograms establish the crystallization of the Nd₂FeMnO₆ system to be orthorhombic distorted structure having Pbnm space group and Fe/Mn cations being randomly arranged at B and B’ sites in the oxygen octahedra. The vibrational modes corresponding to the Fe and Mn cations in the Raman study substantiate the blending of NdMnO₃ and NdFeO₃ sublattices in Nd₂FeMnO₆ double perovskite. XPS measurement evidence the oxidation state of Fe and Mn ions in the oxygen octahedra to be + 3. Magnetic studies reveal room temperature antiferromagnetic ordering in Nd₂FeMnO₆ with a Neel transition at 505 K, are attributed to the Fe³⁺–O–Mn³⁺ and Mn³⁺–O–Mn³⁺ exchange integral chains. Low temperature ZFC/FC curves mark the appearance of thermomagnetic irreversibility at 90 K caused by the magnetic anisotropy of Jahn-Teller Mn³⁺ cations. Dielectric studies disclose an abrupt change in the dielectric constant at the vicinity of the Neel temperature for all measured frequencies, evidencing the existence of magnetodielectricity in Nd₂FeMnO₆ double perovskite.