Angular dependence of the coercivities of Ba ferrite particulate samples: A comparison between theory and experiments

Abstract

We measured the angular dependence of coercivity Hc and remnant coercivity Hr of oriented, Co-Ti substituted, plate-like barium ferrite particulate samples. The experimental results were compared to those modelled by a chain of two oblate ellipsoids. By including the effects of the uniaxial magnetocrystalline anisotropy, the shape anisotropy, and the interaction anisotropy of the ellipsoids, the model of a chain of oblate ellipsoids can explain the magnetization reversal mechanism of the barium ferrite samples. In an individual particle, the magnetic moment tends to reverse coherently because of it large uniaxial magnetocrystalline anisotropy, while in the oriented particulate samples the magnetization reversal of the stacked assembly occurs by symmetrical fanning, consistent with the larger uniaxial magnetocrystalline anisotropy and stronger interaction anisotropy.