2 INTERACTING CUBIC PARTICLES - EFFECT OF PLACEMENT ON SWITCHING FIELD AND MAGNETIZATION REVERSAL MECHANISM

The Landau-Lifshitz-Gilbert equation was used to investigate the effect of interparticle interactions on the remauent states and magnetisation reversal mechanisms of interacting cubic particles. The cubic particle had a uniaxial anisotropy constant in the z direction, K(uz), of 1.96 x 10(5) erg/cc. Interparticle interactions were varied by considering different placements of the second particle. Reversal mechanisms were determined at an applied field of 1.05 x switching field. The reversal mechanism of the isolated cubic particle was also determined. Interparticle interactions were found to have a drastic effect on the switching field. Positive interactions were observed when the particles were separated in the z direction. The reversal mechanisms for the isolated particle and the positively interacting pair were very similar, despite a large difference in the switching field. When the particles were displaced in the x direction the switching field of the interacting pair was reduced from that of the isolated particle. The reversal mechanism for this particle configuration was very complex and asymmetric, due to the non-uniformity of the interaction field. An interesting feature was observed when the particles were separated in the x and z direction. The switching field for this arrangement was also lower than that of the isolated particle, indicating a net negative interaction effect. This simulation result may help to explain the experimental observation of net negative interactions for acicular particles.