Control of the permeability loss-peak frequency of Ni₈₁Fe₁₉ thin films through laser ablation of triangular and square cluster geometries

Laser ablation arrays of triangular and square shaped clusters, comprised of 23 μm diam circular holes, are defined upon 100 nm thick Ni₈₁Fe₁₉ films used to control the rf permeability spectra. Cluster-to-cluster spacing is varied from 200 to 600 μm. For each geometry it is found that the loss peak frequency and permeability magnitude shift lower, in a step-wise fashion, at a cluster-to-cluster spacing between 275 and 300 μm. The nonlinear shift in the behavior of the permeability spectra correlates with a dramatic increase in domain wall density.