Normal mode splitting in interacting arrays of cylindrical permalloy dots

Brillouin light scattering has been exploited to study the dependence of the spin-wave spectrum on the interdot distance in squared arrays of circular permalloy dots with radius R=100 nm, thickness L=50 nm, and interdot spacing (s) variable in the range between 50 and 800 nm. The experimental data have been satisfactorily reproduced using a micromagnetic approach which solves the discretized Landau-Lifshitz-Gilbert equation over a 3x3 matrix of differently spaced circular dots and performing a local Fourier transform. This approach enabled us to clarify that, on reducing the s/R ratio, some of the normal modes existing within each isolated dot increase their frequency retaining their own character. The fundamental mode, instead, splits into three modes characterized by different profiles of the dynamic magnetization. For all these modes, hybriditazion effects have also been observed. (C) 2006 American Institute of Physics.