Magnetic Properties of AOT Functionalized Cobalt-Ferrite Nanoparticles in Search of Hard-Soft Marginal Magnet

An in-depth magnetic characterization of Dioctyl sodium sulfosuccinate (AOT) functionalized cobalt-ferrite nanoparticles (CFNPs) with average sizes from 12 to 22 nm, synthesized by co-precipitation of metal precursors, are discussed here. The M-H hysteresis loop at room temperature for different particle size reveals that the coercivity (Hc) value reaches the maximum (4.1 kOe) at a critical size of 17.4 nm. Furthermore, magnetic relaxation (M versus time) measurements indicate relatively high value of magnetic relaxation time constant (τ) for AOT-assisted CFNPs. Therefore, high Hc, significant saturation magnetization coupled with high τ ensure the permanent magnetic characteristic of the material which have the potential to replace the expensive rare-earth-transition metal-based permanent magnetic materials. On the other hand, materials with comparatively low value of Hc, remanent magnetization will be useful for biomedical applications.