Nanostructured Fe networks studied by ferromagnetic resonance

When a material is sputter-deposited on a nanoporous substrate a network-li ke film is formed on top of the walls that separate the nanochannels, We ha ve carried out an extensive study of the magnetic properties of Fe films de posited on 20 nm pore size nanochannel alumina. Films covering the thicknes s range 5 nm to 100 nm were characterized using ferromagnetic resonance. Fr om the experimental results it was inferred that thinner films are disconti nuous (probably due to the surface roughness) and composed of isolated, par tially oriented, anisotropic particles, The resonance field and linewidth h ave been used to estimate the effective anisotropy and hence an average par ticle aspect ratio of 1.5, which is very similar to what is actually observ ed by direct imaging. The effective anisotropy increases for thicker films and tends to saturate for films thicker than 75 nm.