Morphology Control of Self-Assembled Three-Phase Au-BaTiO₃–ZnO Hybrid Metamaterial for Tunable Optical Properties

Abstract

Microstructural control in metal-dielectric hybrid metamaterials presents enormous opportunities in tailoring the physical properties including the magnetic and optical properties. Here, we demonstrate a strong tunability achieved in the microstructure of self-assembled ordered three-phase Au-BaTiO 3 −ZnO hybrid metamaterial along with its optical properties, grown by a pulsed laser deposition method. Varying the growth temperature, deposition frequency, and template thickness evolves the microstructure by tuning the Au and ZnO pillar geometry as well as the shape and size of the Au nanoparticles capping the ZnO nanowires. The three-phase hybrid metamaterials exhibit unique optical properties, including enhanced nonlinear optical properties, hyperbolic dispersion in the visible and near-infrared wavelength region, and tuned epsilon-near-zero (ENZ) wavelength upon varying the deposition parameters. This study suggests that the three-phase hybrid metamaterials present great potential in the microstructure and optical property tuning that can also be applied to other two-phase and three-phase nanocomposite systems.

Design of 3D Oxide–Metal Hybrid Metamaterial for Tailorable Light–Matter Interactions in Visible and Near‐Infrared Region

“…Different from the typical “top‐down” techniques such as electron beam lithography (EBL), [ 20,21 ] focused ion beam (FIB), [ 22,23 ] and “bottom‐up” electrochemical templating methods, [ 24,25 ] the direct growth of self‐assembled oxide‐metal hybrid metamaterials in the vertically aligned nanocomposite (VAN) thin film form has been demonstrated as an alternative “bottom‐up” approach. [ 26–30 ] Interestingly, highly tunable optical properties such as localized surface plasmon resonance (LSPR) and hyperbolic dispersion shift in the UV–Vis–NIR wavelength region achieved by varying nanostructure aspect ratios, [ 31,32 ] pillar density, [ 32–34 ] and substrate selections [ 35,36 ] all present enormous potentials for these new class of hybrid thin films. Furthermore, by properly selecting the metal nanopillar phase and oxide or nitride matrix, other novel functionalities such as tunable ferroelectric, ferromagnetic, and magnetoelectric coupling and thermal stability can also be enabled.…”

Self‐Assembled Metal–Dielectric Hybrid Metamaterials in Vertically Aligned Nanocomposite Form with Tailorable Optical Properties and Coupled Multifunctionalities

“…[ 113 ] Therefore, due to the anisotropic nanostructure and lattice strain coupling at the pillar/matrix and film/substrate interfaces, the VAN hybrid thin films are expected to have enhanced SHG response compared with the pure NLO materials. [ 43,102,111 ] More interestingly, noncentrosymmetric and anisotropic nature has been demonstrated in the Au–TaN hybrid thin film with both phases of centrosymmetric crystal structures. [ 45 ] The comparison of the SHG intensity of TaN and Au–TaN films as a function of incident polarization angle fixed at 0° (P‐out) and 90° (S‐out) are shown in Figure a,b, respectively.…”

“…It is noted that the HMM transition wavelengths show a noticeable blue-shift from 868 nm for the Au-BTO film to 669 nm for Au x Ag 1Àx -BTO film, indicating higher electron density as other study reported. [46,102]…”

Recent Advances in Vertically Aligned Nanocomposites with Tunable Optical Anisotropy: Fundamentals and Beyond

“…All of these examples have shown great potentials in achieving various artificial metamaterial designs possessing relatively good periodicity, large-scale surface coverage, epitaxial quality, atomic-sharp interface, as well as tunable functionalities. Table 1 summarizes the recent ceramic-based wire metamaterials (or VANs) grown by physical vapor deposition technique, and their reported functionalities [51][52][53][54][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. The ultimate goal is to realize an alternative method in fabricating functional heterostructures or metamaterials for applications including sensing, high-temperature plasmonics, nonlinear optics, ultrafast switching, as well as fundamental explorations, including tunable plasmonics or coupled multifunctionalities, using these highly anisotropic media.…”