Magneto-electric coupling and multifunctionality in BiFeO3–CoFe2O4 core-shell nano-composites

Abstract

The presence of magneto-electric composites in the form of core-shell nanostructures improves their multifunctional characteristics, which makes them suitable for use in diverse fields ranging from medicine to data storage industry. Among these composites, the perovskite/spinel combination has a huge potential. To explore the multifunctional response of this arrangement, we synthesised a series of (1-x)BiFe0.95Mn0.05O3/xCoFe2O4 (x = 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7) nano core-shells by a sonication-assisted sol-gel auto combustion method. Through structural analysis, the peaks corresponding to both perovskite and spinel phases were identified and the number of peaks belonging to each phase were found to vary according to their composition. Surface images captured using scanning tunnelling microscopy confirmed the formation of a CoFe2O4 core covered with Mn-doped BiFeO3 shells. The effect of increased concentration of CoFe2O4 on dielectric properties was analysed on the basis of the local charge transport mechanism in a broad frequency range. With the help of PE loops, energy density was calculated to investigate the potential of these compositions in energy storage devices. Magnetic response analysis revealed that saturation magnetisation increased as CoFe2O4 contents were increased while coercivity remained almost constant. The significant signal of the magneto-electric effect indicated that these composites have a potential for application in multistate memory devices.