Origin of the Intrinsic Coercivity Field Variations and Magnetic Study of ε-Fe₂O₃

Origin of the intrinsic coercivity field variations observed by hysteretic measurements established by Nikolic et al. was investigated in detail by ZFC/FC measurements. In this study, magnetic behavior of the samples is further examined by calculation of the ZFC $M_n\left(T\right)$ and $M_n\left(H\right)$ first derivatives. Performed study showed that the main contribution to the measured coercivity comes from the ε-Fe₂O₃ particles, characterized by $Hci=24\text{kOe}$, although both samples posses $\text{SPM}$ ε-Fe₂O₃ fraction. As a result, Hci values of the samples are differed dependent on the quantity of the SPM ε-Fe₂O₃ particles in the sample. Mechanism of the intrisic coercivity field variations is discussed.