Interplay between morphology, mechanical properties, and magnetic characteristics of permalloy coated aerogels

We investigate the growth of permalloy (Ni₈₀Fe₂₀, Py) magnetic thin films on polyurea crosslinked silica aerogels as well as Superelastic Shape Memory Polyurethane Aerogels (SSMPA). The impact of the substrate properties (Young’s modulus, surface roughness) on the magnetic coercivity and saturation fields of varying thicknesses of Py were investigated. Following deposition, the adhesion of the bilayer is evaluated, while microstructural properties and coverage area are determined by FE-SEM. We find that for Py thicknesses of 100 nm, a thin, uniform coating is formed for both aerogel samples. However, at 10 nm, the film exhibits similar morphology to the underlying aerogels. Further, the magnetic properties are evaluated by the Kerr effect. Scaling of the coercive field is observed with film thickness, as is traditionally observed in magnetic thin films. However, significant coercivity differences are observed between the two aerogels. We attribute this to the morphological and mechanical differences of the two aerogels.