My watch list
my.chemeurope.com  
Login  

Self-assembly approach to engineer nanoscale metamaterials

09-Jan-2017

LANL

Schema of a self-assembled metamaterial

A research team has developed a novel self-assembly approach to fabricate nanoscale metamaterials made of metallic nanopillars in oxide matrices. This method enables control over the density, size, and alignment of nanopillars instead of a random distribution of particles in the oxide matrix. This control opens new possibilities for large scale, reliable development of nanoscale photonic materials that enhance light-matter interactions at the nanoscale for novel applications.

Significance of the work

Metamaterials are engineered to have a property that is not found in nature. They are made from assemblies of multiple elements fashioned from composite materials. The materials are usually arranged in repeating patterns, at scales that are smaller than the wavelengths of the phenomena they influence. Metamaterials derive their properties from their designed structures rather than the properties of the base materials.

These new materials exhibit exotic optical properties that have potential promising applications, such as super-resolution imaging, cloaking, hyperbolic propagation, and ultrafast phase velocities. Bottom-up template-assisted electroplating and top-down nanofabrication techniques have been examined to create these materials. However, most metamaterials require costly and tedious fabrication techniques with limited paths toward reliable large-scale production. This limits the applicability of the materials for useful applications.

The team developed a drastically different approach to fabricate large area nanostructured metamaterials. The one-step self-assembly process uses a pulsed laser deposition method to fabricate the nanoscale metamaterials. The researchers created films with vertically aligned gold nanopillars (approximately 20 nm in diameter) embedded in metal oxide matrices. Compared with other fabrication techniques, this self-assembly method enables control over the density, size, and alignment of the nanopillars. The nanomaterials have the same crystal structure as the underlying substrate. The results suggest that self-assembled metal-oxide nanostructures could be a promising new material platform to control and enhance optical response at nanometer scales for a variety of useful applications.

Achievements

The researchers discovered that the density of self-assembled gold nanopillars in the vertically aligned nanocomposite films could be easily tailored by controlling the content of gold in the composite target for the laser. The investigators determined the formation mechanism of the self-assembled structures. Gold atoms diffuse and nucleate as islands, while oxide atoms nucleate to form the overall matrix via layer-by-layer growth. After the initial nucleation, the gold and metal oxide atoms further diffuse and grow in the form of gold nanopillars embedded in a metal oxide matrix. The unique gold nanopillar-oxide matrix nanocomposite structure forms through the film thickness. Characterization measurements supported by full-wave simulations and theory demonstrated the unidirectional optical properties of the metamaterials. The team’s model predicted exotic properties, such as zero permittivity responses and topological transitions, which could enable useful applications.

Facts, background information, dossiers
  • new materials
  • composite materials
  • self-assembling particles
  • self assembly
More about Los Alamos National Laboratory
  • News

    Chemical treatment improves quantum dot lasers

    One of the secrets to making tiny laser devices such as opthalmic surgery scalpels work even more efficiently is the use of tiny semiconductor particles, called quantum dots. In new research at Los Alamos National Laboratory's Nanotech Team, the ~nanometer-sized dots are being doctored, or ... more

    How low-cost fuel cell catalysts work exactely

    In order to reduce the cost of next-generation polymer electrolyte fuel cells for vehicles, researchers have been developing alternatives to the prohibitively expensive platinum and platinum-group metal (PGM) catalysts currently used in fuel cell electrodes. New work at Los Alamos and Oak R ... more

    Perovskite edges can be tuned for optoelectronic performance

    In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating innovative 2D layered hybrid perovskites that allow greater freedom in designing and fabricating efficient optoelectronic devices. Ind ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE