The resonance frequency of ferromagnetic particles with surface anisotropy was investigated by micromagnetic simulation. Two kinds of calculations were done: those with Aharoni surface anisotropy and those with Néel-Brown surface anisotropy. In Aharoni surface anisotropy, the relationship between the resonance frequency and particle size D was in agreement with Shilov's theory. In Néel-Brown surface anisotropy, the resonance frequency was proportional to 1/b, where b was the length of the short axis.
2008 The Magnetics Society of Japan