Using highly uniform and smooth Selenium colloids as low-loss magnetodielectric building blocks of optical metafluids

We systematically analyzed magnetodielectric resonances of Se colloids for the first time to exploit the possibility for use as building blocks of all-dielectric optical metafluids. By taking synergistic advantages of Se colloids, including (i) high-refractive-index at optical frequencies, (ii) unprecedented structural uniformity, and (iii) versatile access to copious quantities, the Kerker-type directional light scattering resulting from efficient coupling between strong electric and magnetic resonances were observed directly from Se colloidal suspension. Thus, the use of Se colloid as a generic magnetodielectric building block highlights an opportunity for the fluidic low-loss optical antenna, which can be processed via spin-coating and painting.