Structure-based magneto-dielectric response in Zn and V Co-doped NiFe2O4 for magnetic and spintronic applications

Abstract

This study implemented the sol-gel method to synthesize NiFe2O4 (NFO) and Ni0.6Zn0.4Fe1.94V0.06O4 (NZFVO) nanoparticles. X-ray diffraction (XRD) with Rietveld refinement confirmed cubic spinel structures, while FESEM and TEM showed that dopants caused lattice distortion, leading to larger grains and crystallites in NZFVO. First- principles calculations show a reduced direct bandgap and conduction band splitting in NZFVO, attributed to strong d–p orbital hybridization. Mulliken population analysis indicates off-center cationic displacements and increased covalency, further supporting the observed dielectric and magnetic behavior. Dielectric measurements confirmed lower permittivity and loss in NZFVO, indicating its suitability for low-loss spintronic devices. Magnetic characterization shows enhanced saturation magnetization, lower coercivity, and reduced Curie temperature (Tc) in NZFVO, resulting from optimized cation distribution and weakened anisotropy. Therefore, NZFVO, with high saturation magnetization (~72.4 emu/g) and low coercivity (~6.6 Oe), is well-suited for low-field detection, magnetic biosensing, and room-temperature sensing. Its reduced bandgap and strong d-p hybridization enable spin-dependent conduction, while moderate conductivity and low resistivity make it a promising channel material for spin-based transistors and logic devices.