title: Self-Assembled Epitaxial Au-Oxide Vertically Aligned Nanocomposites for Nanoscale Metamaterials.
abstract: Metamaterials made of nanoscale inclusions or artificial unit cells exhibit exotic optical properties that do not exist in natural materials. Promising applications, such as super-resolution imaging, cloaking, hyperbolic propagation, and ultrafast phase velocities have been demonstrated based on mostly micrometer-scale metamaterials and few nanoscale metamaterials. To date, most metamaterials are created using costly and tedious fabrication techniques with limited paths toward reliable large-scale fabrication. In this work, we demonstrate the one-step direct growth of self-assembled epitaxial metal-oxide nanocomposites as a drastically different approach to fabricating large-area nanostructured metamaterials. Using pulsed laser deposition, we fabricated nanocomposite films with vertically aligned gold (Au) nanopillars (∼20 nm in diameter) embedded in various oxide matrices with high epitaxial quality. Strong, broad absorption features in the measured absorbance spectrum are clear signatures of plasmon resonances of Au nanopillars. By tuning their densities on selected substrates, anisotropic optical properties are demonstrated via angular dependent and polarization resolved reflectivity measurements and reproduced by full-wave simulations and effective medium theory. Our model predicts exotic properties, such as zero permittivity responses and topological transitions. Our studies suggest that these self-assembled metal-oxide nanostructures provide an exciting new material platform to control and enhance optical response at nanometer scales.
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Leigang
authors.initials: L
authors.lastname: Li
authors.forename: Liuyang
authors.initials: L
authors.lastname: Sun
authors.forename: Juan Sebastian
authors.initials: JS
authors.lastname: Gomez-Diaz
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Nicki L
authors.initials: NL
authors.lastname: Hogan
authors.affiliation: Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.forename: Fauzia
authors.initials: F
authors.lastname: Khatkhatay
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Wenrui
authors.initials: W
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Jian
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Jijie
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Qing
authors.initials: Q
authors.lastname: Su
authors.forename: Meng
authors.initials: M
authors.lastname: Fan
authors.forename: Clement
authors.initials: C
authors.lastname: Jacob
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Xinghang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Quanxi
authors.initials: Q
authors.lastname: Jia
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.|Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Matthew
authors.initials: M
authors.lastname: Sheldon
authors.forename: Andrea
authors.initials: A
authors.lastname: Alù
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wang
keywords: BaTiO3; Nanoscale metamaterial; gold nanopillar; plasmonic property; self-assembled metamaterial; vertically aligned nanocomposite (VAN)