Tuning magnetic storage properties through neodymium substitution in CoCr₂O₄ nanostructures: A chemical synthesis approach and DFT calculations

Neodymium-doped CoCr₂O₄ nanoparticles were synthesized via a chemical synthesis route to investigate their structural, microstructural, compositional, and magnetic properties. X-ray diffraction (XRD) analysis confirmed the formation of a single-phase cubic spinel structure with high crystallinity and slight lattice expansion due to neodymium doping. Scanning Electron Microscopy (SEM) revealed a quasi-spherical morphology with uniform particle distribution, while Energy Dispersive X-ray Analysis (EDAX) confirmed the elemental composition, showing the successful incorporation of neodymium without impurities. Fourier Transform Infrared (FTIR) spectroscopy highlighted characteristic metal-oxygen vibrational bands, with shifts in peak positions reflecting changes in the local bonding environment due to neodymium substitution. Magnetic studies, including field-cooled (FC) and zero-field-cooled (ZFC) measurements, indicated modifications in Curie temperature and magnetic transitions, with doped samples exhibiting enhanced superparamagnetic behavior. DFT calculations were conducted to complement the overall discussion, proving that Nd³⁺ (4f³) orbitals play a fundamental role on controlling the structural, electronic and magnetic properties of spinel chromites. This study is novel in its combined use of experimental characterization and first-principles DFT calculations to probe the role of Nd³⁺ doping in tuning the magnetic and structural behavior of CoCr₂O₄. The integration of low-temperature synthesis with theoretical modeling provides new insights into rare-earth-induced modulation of exchange interactions in spinel chromites, highlighting potential applications in magnetic storage and spintronic devices.