Effect of disorder studied with ferromagnetic resonance for arrays of tangentially magnetized sub-micron Permalloy discs fabricated by nanosphere lithography

摘要

Tangentially magnetized trigonal arrays of sub-micron Permalloy discs arecharacterized with ferromagnetic resonance to determine the possiblecontributions to frequency and linewidth from array disorder. Each array isfabricated by a water-surface self-assembly lithographic technique, andconsists of a large trigonal array of 700 nm diameter magnetic discs. Eacharray is characterized by a different degree of ordering. Two modes are presentin the ferromagnetic resonance spectra: a large amplitude, `fundamental' modeand a lower amplitude mode at higher field. Angular dependence of the resonancefield in a very well ordered array is found to be negligible for both modes.The relationship between resonance frequency and applied magnetic field isfound to be uncorrelated with array disorder. Linewidth is found to increasewith increasing array disorder.