ZrC-diluted NiFe₂O₄ spinel composites: interfacial anisotropy boost and tunable ferrimagnetism for EMI shielding

Nickel ferrite (NiFe₂O₄) and ZrC-based composites were synthesized and characterized through structural, morphological, spectroscopic, and magnetic analyses to investigate the influence of ZrC incorporation on their magnetic behaviour. X-ray diffraction (XRD) confirmed the formation of a cubic spinel NiFe₂O₄ phase along with a distinct ZrC phase without any detectable impurities, indicating successful composite formation. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) revealed uniform dispersion of ZrC within the ferrite matrix, leading to the formation of well-defined heterointerfaces. Raman spectroscopy further supported the composites' phase purity and the minor distortions brought on by the addition of ZrC. X-ray photoelectron spectroscopy (XPS) confirmed the increased oxygen vacancy concentration and interfacial charge redistribution, confirming strong electronic coupling at the NiFe₂O₄/ZrC interface. Vibrating sample magnetometer (VSM) measurements demonstrated ferrimagnetic behaviour for all samples, with a systematic reduction in saturation magnetization from 2.702 ± 0.135 to 0.978 ± 0.049µ_B per f.u. as ZrC content increases, attributed to the dilution of the ferromagnetic domains and A-O-B superexchange interactions. In contrast, the magnetocrystalline anisotropy constants (K) significantly increase from 0.52 ± 0.03 to 2.26 ± 0.11 J m^-3, indicating enhanced interfacial anisotropy. Langevin analysis further revealed a decrease in domain density from 2.33 ± 0.12 to 0.86 ± 0.04 cm^-3, suggesting fragmentation of magnetic domains due to interfacial effects, and the effective magnetic moment (M_eff) remained nearly constant (1.70 ± 0.09 and 1.77 ± 0.09µ_B). Element-specific X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) at the Ni and Fe L_2,3-edges confirm stable Ni²⁺ and Fe³⁺ valence states and reveal suppression of sublattice magnetic moments caused by interfacial spin disorder. The observed reduction in magnetizations, combined with enhanced anisotropy and interfacial characteristics, is consistent with reported ferrite-carbide systems, indicating potential suitability for electromagnetic-related applications. These findings provide new insights into tuning magnetic behaviour in ferrite-carbide composites through controlled interfacial engineering.