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

• NiFe 2 O 4 (NFO) and Ni 0.6 Zn 0.4 Fe 1.94 V 0.06 O 4 (NZFVO) nanoparticles are crystallized at 900 ℃ into the cubic mixed spinel structure with larger lattice size and grain growth in NZFVO. • First-principles calculations reveal a reduced direct bandgap (∼1.18 eV in NZFVO vs ∼2.63 eV in NFO) and conduction band splitting due to d–p orbital hybridization, enhancing spintronic potential. • Mulliken population analysis indicates off-center cation displacements and increased covalency in NZFVO, supported by lower effective atomic charges and stronger Ni–O and Fe–O bonding. • NZFVO exhibits significantly lower dielectric constant and loss, higher AC conductivity, and lower resistivity, making it ideal for low-loss spintronic device integration. • NZFVO shows enhanced saturation magnetization (∼72.4 emu/g), reduced coercivity (∼6.6 Oe), lower Curie temperature (320 °C), and weakened magnetic anisotropy, indicating suitability for room-temperature magnetic and spintronic applications. This study implemented the sol-gel method to synthesize NiFe 2 O 4 (NFO) and Ni 0.6 Zn 0.4 Fe 1.94 V 0.06 O 4 (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 ( T c ) 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.