High-aspect-ratio mushroom-like silica nanopillars immersed in air: epsilon-near-zero metamaterials mediated by a phonon-polaritonic anisotropy.

ABSTRACT: Epsilon-near-zero metamaterials offer opportunities for intriguing electromagnetic-wave phenomena. Here we experimentally demonstrate that silica perpendicular nanopillars immersed in air exhibit a uniaxial epsilon-near-zero response mediated by phonon polaritons in the mid-infrared range. Unique mushroom-shaped heads on nanopillars play a crucial role to realize SiO₂ metamaterials over a large area in our self-assembled fabrication process with block copolymers, polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS). SiO₂ nanopillars having heights of 80 nm, 200 nm, and 300 nm (aspect ratios up to ∼13) are obtained after calcination at 450 °C and the electromagnetic responses are evaluated using a mid-infrared ellipsometric apparatus. For nanopillars with

SUBMITTER: Ito K 

PROVIDER: S-EPMC9064425 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature