THE INFLUENCE OF INTERFACIAL EXCHANGE ON THE COERCIVITY OF ACICULAR COATED PARTICLE

The acicular coated magnetic particles are considered as magnetostatic interacting dual-component particles with interfacial exchange coupling. The calculations show that the coercivity varies with shell thickness and the relative magnetic properties between core and shell. When increasing the shell thickness, it is found that the initial slope of the increasing coercivity depends on the anisotropy energy of the shell, while the saturation level of the coercivity depends on the interfacial interaction. The calculated results show that a thin layer of shell is responsible for the increase of the coercivity. The best fitting curve for the available experimental data gives interfacial exchange coupling, A = 5.87 X 10(-8) erg/cm, and shell anisotropy constant, K = 0.52 X 10(6) erg/cm3.