Micromagnetic Simulation Of Low-dimensional Magnetic Materials

Micromagnetic simulation is suitable for investigating the dynamic evolution and the magnetic reversal process of ferromagnetic materials.The dynamic susceptibilities of permalloy-like nanowires (20 nm×500 nm×20 nm) have been investigated using the Micromagnetic simulation. The investigated systems show two resonant peaks associated with a "bulk" and an "edge" mode, which are attributed to the local effective field relevant to the local magnetic moments. A local analysis for ferromagnetic resonance calculation has been developed. It handles the local magnetic moments at the edge and the middle of the nanowire, respectively. The resonant frequencies of the "edge" mode are directlyproportional to M_s or A^1/2 under the same fundamental length scale, i.e., the exchange length.The magnetic reversal of the antidots permalloy arrays, one of the candidates of potential high density storage media, have been also investigated using the Micromagnetic calculation. The pattern systems show very complicated magnetic performance. Antidots arrays process unique magnetic properties, such as their shaped-induced magnetic anisotropy, domain structure, and pinning in the laterally confined geometries. The investigated systems present domain wall during the magnetic reversal process. The domain wall structure transforms from Néel wall into Bloch wall as the film thickness increasing, and the coercive force increases when the magnetic reversal is dominated by Néel wall and then decreases while Bloch wall is dominative during the magnetic reversal. The holes are to be the center of nucleation when the separation distance between antidotes is small or to be the center of pinning while the separation distance between antidotes is large under the same film thickness. The coercive force increases/decreases when the holes are to be the center of nucleation/pinning.