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

Abstract

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 ( $H_{c}$ ) 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 ( $\tau$ ) for AOT-assisted CFNPs. Therefore, high $H_{c}$ , significant saturation magnetization coupled with high $\tau $ 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 $H_{c}$ , remanent magnetization will be useful for biomedical applications.