Nanoporous FePd alloy as multifunctional ferromagnetic SERS-active substrate

Nanoporous materials represent a unique class of materials, given to their unforeseen magnetic, mechanical, optical and catalytic properties arising from their network of pores and ligaments. Here a polycrystalline thin film of FePd is considered as a starting system, in which the porosity is induced via dealloying. This process determines the removal of iron from the alloy and the diffusion of palladium on the surface, which in turn influences the evolution of the material's composition, magnetic properties and optical properties. In addition, from the magnetic point of view, the material acquires a more isotropic behaviour while the magnetic moment decreases due to the removal of iron. In the same way, there is an improvement of the surface enhanced Raman scattering as the dealloying proceeds, due to the formation of clusters of palladium on the surface. This mixture of optical and magnetic properties, combined with its high corrosion resistance and biocompatibility, gives the system a strong multifunctional connotation, paving the way for new applications, ranging from magnetic trapping to detection of low concentration of molecules.