Abstract
Localized surface plasmons are under intensive study since long ago because they play a very important role in the optical properties of metallic systems. In particular, they become especially relevant in the optical properties of nanostructures, such as tiny particles embedded in dielectric matrices. The intensity as well as the spectral position of these resonances strongly depends on a variety of parameters such as the size, the shape, the concentration of the metallic particles or the refractive index of the matrix. The vast majority of the studies have been so far devoted to study noble metal particles since their free electron contribution to the optical properties in the infrared and visible spectral range is predominant, exhibiting also a low damping constant. In other metals such as palladium, platinum, cobalt, nickel or iron, the free electron contribution to the optical properties is smaller, and have a higher damping constant, therefore their surface plasmon resonances appear broader and less defined. On the other hand, some of these metals like Fe, Co and Ni, possess spontaneous magnetization which enables them to present magneto-optical properties, which are absent in noble metals. This characteristic can be used to design new kind of plasmonic structures. Moreover, different theoretical works have suggested that surface plasmon resonance of magnetic metallic nanoparticles could enhance the magneto-optical activity with respect to that of a continuous medium. However, the size of the nanoparticles under consideration is always much smaller than the wavelength of light and the interaction between the particles was rarely not considered. But the particle size and the radiative coupling between nanoparticles strongly modify the optical properties of the system and, therefore, it may also modify its magneto-optical response. This is precisely the scope of this work, where we analyze the dependence of the magneto-optical properties on the size and on the dielectric enviromnent of a system consisting on periodically arranged Ni nanowires embedded in a dielectric enviromnent. Such system has already shown to exhibit interesting effects, such as an enhancement of the magnetooptical Kerr rotation, whose origin will be pointed out here. We will show that the enhancement is due to a surface plasmon resonance of the Ni nanowires, its spectral position depending on the wire diameter.
© 2007 IEEE
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