Effect of Annealing Temperature and Preparation Condition on Magnetic Anisotropy in Nanocrystalline Cobalt Ferrite

Nanocrystalline cobalt ferrite (CoFe
₂
O
₄
) materials have been synthesized by citrate precursor and co-precipitation method. Samples are annealed at different temperatures to obtain the different nanocrystallite-size materials. All the samples crystallize to
Fd3̅m
space group in cubic symmetry. Magnetic hysteresis loops measurement has been carried out at room temperature using a vibrating sample magnetometer (VSM). The magnetic data in the saturation region have been analyzed by employing the law of approach (LA) to saturation technique. The anisotropy constant (
K
₁
) is found to be higher in citrate precursor derived samples. The saturation magnetization (
M
_s
), coercivity (
H
_c
) , remanent magnetization (
M
_r
) and anisotropy constant (
K
₁
) increases with the increase of crystallite size.