Dipolar Standing Waves Excited in Ferromagnetic Wire Arrays

Abstract

Recently, unique multiple microwave absorption has been observed in ferromagnetic Ni₈₀Fe₂₀ wire arrays with lateral periodicity. As the origin of this phenomenon, we have proposed the excitation of dipolar standing waves arising from a novel collective motion of giant magnetic moments. In the present study, the dependence of the microwave absorption characteristics on the wire spacing, width, and number of wires was investigated to confirm our model. The intensity of the absorption with higher wave number decreased as wire spacing increased. Complex spectra were observed in arrays with wider wires, suggesting an overlap of main and multiple absorption. No change was obtained in the microwave absorption characteristics when the number of wires was varied between 50 and 500. These results imply the validity of the dipolar standing wave model.