It is generally accepted that the magnetic component of light has a minor role in the lightmatter interaction. The recent discovery of metamaterials has broken this traditional understanding, as both the electric and the magnetic field are key ingredients in metamaterials. The top-down technology used so far employs noble metals with large intrinsic losses. Here we report on a bottom-up approach for processing metamaterials based on suspensions of monodisperse full dielectric silicon nanocavities with a large magnetic response in the near-infrared region. Experimental results and theory show that siliconcolloid-based liquid suspensions and photonic crystals made of two-dimensional arrays of particles have strong magnetic response in the near-infrared region with small optical losses. Our findings might have important implications in the bottom-up processing of large-area low-loss metamaterials working in the near-infrared region.

A straightforward synthetic route to produce colloidal photonic crystals containing dielectric planar defects of controlled thickness (see Figure) is presented. Allowed states that arise within the stop band as a result of this doping greatly modify the reflectance properties of the crystals, in good agreement with theoretical predictions.

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Raman signal enhancement induced by silicon nanoparticles.

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Several configurations of colloidal wires are obtained by infiltration of charge‐stabilized polystyrene spheres into cylindrical pores of a silicon membrane (see figure). As channel dimensions are comparable to those of particles, wirelike arrangements are governed by the ratio between the pore diameter and the particle diameter. Also, Coulomb repulsion between particles plays a very important role in the particle ordering.

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