Biotemplate-assisted medium-entropy spinel ferrite: structure-property correlation of magnetic, electrical, and dielectric behaviour

Medium-entropy ferrites have emerged as a versatile class of materials with tunable multifunctional properties arising from configurational disorder. Herein, a biotemplate-assisted synthesis of a medium-entropy spinel ferrite, [Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 ]Fe 2 O 4 , is reported using albumen as a sustainable stabilizing agent. Structural analysis confirms the formation of a single-phase cubic spinel with homogeneous cation distribution. X-ray photoelectron spectroscopy reveals mixed valence states, facilitating charge transport and magnetic interactions. The material exhibits a saturation magnetization of 91.7 emu/g at 5 K and 68.34 emu/g at 300 K, governed by strong A-B super exchange interactions and cation disorder. Impedance spectroscopy indicates thermally activated conduction with an activation energy of ~ 0.4 eV, consistent with a polaron hopping mechanism. Dielectric analysis shows Maxwell-Wagner-type interfacial polarization, leading to high permittivity at low frequencies. The combined effects of entropy stabilization, cation disorder, and microstructure underpin the observed magnetic and dielectric responses, highlighting the potential of bio-templated medium-entropy ferrites for functional electronic materials.