The importance of the polycrystalline microstructure of Co layer on the swi
tching mechanism of permalloy/Co composite film was investigated by the mic
romagnetic simulation. The grain texture effect of Co element significantly
influences the switching processes as the diameter of grain size is larger
than the magnetization coherent length. The random anisotropy crystallite
of Co grain causes the irregularity of the magnetic reversal and rotation a
nd induces the Barkhausen noise during reversal.