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We investigated the magneto-optical response of chemically synthesized iron oxide magnetic nanocrystals, optically coupled with ordered planar arrays of plasmonic nanoparticles. We compare the signals from two classes of systems, featuring either Au or Ag as the plasmonic counterpart. The localized surface plasmon resonance of the Ag and Au nanoparticles arrays were superimposed or detuned, respectively, with respect to the dominant magneto-optical transitions of the magnetic material. Under resonance, a significant enhancement of the magneto-optical signal was observed. In both cases, we could separate the purely plasmonic and the magnetic contributions in the magneto-optical spectrum of the optically coupled composite based on their different magnetic-field dependence.

We report the fabrication of 2-dimensional arrays of Au nanoparticles (NPs) with flexibly tunable shape and arrangement, realized by deposition onto self-organized ridge-valley structures at the LiF(110) surface. Tuning the array fabrication conditions, the NP mean size, spacing, and aspect ratio could be controllably varied, allowing us to achieve a variety of 2-dimensional array morphologies. We discuss the consequences of the morphological tuning on the plasmonic response focusing on two particularly instructive cases: in-plane circular NPs arranged on a rectangular array and coherently aligned elongated ellipsoidal NPs laid on a square lattice. Comparing the data with model calculations allowed us to ascribe the optical birefringence of the arrays to the interplay of intrinsic and collective effects. The remarkably narrow width of the plasmonic resonance in these arrays is shown to arise as a consequence of the partial compensation of the dipolar coupling fields between neighboring nanoparticles.

We report a spectroscopic ellipsometry investigation of the interaction of nanoporous cluster-assembled Au films with pure ethanol in a liquid environment. The Au films were first characterized in atmosphere in terms of the mean size of the constituent clusters and their porosity. Upon immersion in liquid, a clear correlation between the relative density of the films and the corresponding fraction of pores that could be filled by ethanol molecules was observed. Low-density porous Au structures exhibit abundant open pores, accessible by molecules from the ambient, whereas for higher-density structures the fraction of accessible pores sharply drops. We found evidence that the pore accessibility in cluster-assembled films with pore dimension in the sub-10 nm range is strongly dependent on fine morphological details of the solid scaffold.

The surface magnetism of an iron film grown on a MgO(100) substrate has been studied by means of spin polarized metastable de-excitation spectroscopy (SPMDS) as a function of the exposure to oxygen. The O2pstates are magnetically coupled to the iron film and exhibit a splitting in energy ΔEO2pbetween the majority and the minority components. The behavior of ΔEO2pwith oxygen exposure demonstrates that the magnetic coupling of the O2pstates is strongly dependent on the local environment of the adsorbed oxygen atoms and provides a clear indication of the magnetic shielding induced by oxygen diffusion in sub-surface sites.