Composite Gold/Magnetite Plasmonic-Magnetic Media Based on Self-Organization

We report the fabrication and the optical characterization of a composite system featuring optically-coupled plasmonic and magnetic components consisting of a 2-dimensional layer of magnetite (Fe3O4) nanocrystals (NC) laid onto a self-organized planar array of Au nanoparticles (NP). The regular arrays of Au NPs were fabricated by deposition onto a LiF(110) insulating surface nanopatterned by self-organization methods. The magnetite NCs were deposited from colloidal suspension onto the Au array by dip-and-dry procedures. The Au NPs exhibit a sharp localized surface-plasmon resonance (SPR) in their optical response at wavelength of ≈550-600 nm. The SPR redshifts by ≈25 nm upon the deposition of the magnetite NC, due to the optical coupling between the plas- monic and the magnetic media. Optical modelling and atomic-force microscopy characterization suggest that a single, highly homogeneous monolayer of magnetite NC was formed on top of the Au NP array. The magnetite NC preserve their magnetic response following the deposition.