MICROMAGNETIC CALCULATION OF APPLIED FIELD-EFFECT ON SWITCHING MECHANISM OF A HEXAGONAL PLATELET PARTICLE

The effect of the applied field on the switching mechanism of a hexagonal platelet particle was investigated by computer simulation. The fields were applied perpendicular to the platelet plane which is the easy axis direction of the platelet. As the applied field increases, the switching mechanism changes from the normal vortex mode (in which the magnetic moments in a hexagonal plane rotate about the center of the plane, and the moments in the top and bottom planes rotate in the same direction) to the crater mode (in which the moments do not form a vortex, and the moments at the center of the hexagon switch faster than the moments at the corners), then to the quasi-coherent rotation mode and finally to the twisted vortex mode (in which the moments in the top and bottom planes rotate in opposite directions).