Nature of magnetic interactions in [Formulaomitted]-Co(OH) sub(2) nanoparticles

Magnetic properties of [Formulaomitted]-Co(OH)[Formulaomitted] nanoparticles covering temperature range of 5-300K in magnetic field upto 50kG are studied. Zero-field-cooled and field-cooled susceptibility as a function of temperature curves in different applied magnetic fields are seen to bifurcate at [Formulaomitted]. Curie-Weiss fit of zero-field-cooled susceptibility curve well above [Formulaomitted] yields [Formulaomitted] and ionic magnetic moment [Formulaomitted]. Magnetization as a function of applied magnetic field curve below [Formulaomitted] shows a two-step transition to ferromagnetic state. Strength of three possible exchange interactions among Co[Formulaomitted] ions in [Formulaomitted]-Co(OH)[Formulaomitted] nanoparticles is also determined. We find that the present system orders antiferromagnetically at [Formulaomitted], with a dominant intralayer ferromagnetic coupling and a weaker interlayer antiferromagnetic coupling.