Superspin-glass dynamics and magnetic memory in ZnFe₂O₄ nanoparticles synthesized via a green egg-white-assisted...

ZnFe₂O₄ nanoparticles were successfully synthesized using a simple and eco-friendly egg-white-assisted route, offering a cost-effective approach for producing spinel ferrite nanomaterials. X-ray diffraction and Rietveld refinement confirm the formation of a single-phase cubic spinel structure (Fd3̄m), while transmission electron microscopy reveals nearly uniform nanoparticles with an average size of ∼40 nm. X-ray photoelectron spectroscopy suggests partial cation redistribution at the surface, which can influence the magnetic behavior. Magnetic studies show superparamagnetic-like characteristics at higher temperatures with a blocking temperature of T _B ≈ 67 K and irreversibility below T _irr ≈ 70 K. The observed non-saturating magnetization and finite coercivity indicate the presence of interparticle interactions. AC susceptibility measurements exhibit a frequency-dependent freezing temperature (T _f ≈ 90 K), and dynamic scaling analysis yields a relaxation time τ ₀ ≈ 10^-7 s and critical exponent zν ≈ 7, suggesting superspin-glass behavior associated with interacting nanoparticles. This is further supported by Vogel-Fulcher fitting and magnetic memory measurements. The combined effects of particle size, surface spin disorder, and dipolar interactions are responsible for the observed magnetic behavior. The present study demonstrates that green synthesis routes can effectively produce ZnFe₂O₄ nanoparticles with tunable magnetic properties, making them promising for potential applications in magnetic devices and sensing technologies.