Dipole-dipole interaction in arrays of Fe/Fe$_x$O$_y$ core/shell nanocubes probed by ferromagnetic resonance

摘要

This paper represents a detailed theoretical study of the role of thelongrange magnetic dipole-dipole interaction evidenced by the ferromagneticresonance (FMR) spectra for the ordered arrays of cubic nanoparticles. We showthat the size of the array essentially controls the stability of the system,allowing to suppress the intermittent low-field excitations starting from thearrays formed by 6x6 nanoparticles. Our numerical simulations allow todetermine the threshold inter-particle distance (around 80 {\div} 100 nm),after which the dipole-dipole interaction becomes negligible so that the FMRspectrum of the nanoparticle arrays becomes the same as the spectrum featuredby a single nanoparticle. We also compare our simulations with experimentalFMR-spectra of 24 Fe/Fe$_x$O$_y$-nanocubes irregularly placed on a substrate.