Metamaterials are a new type of manufactured substance. They have been defined by Rodger M. Walser of the University of Texas as “macroscopic composites having a manmade, three-dimensional, periodic cellular architecture designed to produce an optimized combination, not available in nature, of two or more responses to specific excitation”.
Metamaterials are composite materials that are not found in nature.
Man made or engineered metamaterials are electromagnetic composites, only discovered in 1999. Engineered metamaterials are initially designed using computer models. When a computer model indicates a chemical structure and composition that may give a material with the desired properties, the metamaterial can then be synthesized in the laboratory.
Superatoms and Making Metamaterials
Metamaterials are made from clusters of superatoms. Superatoms themselves are sometimes referred to as metamaterials but they are the building blocks of metamaterials. A superatom is a structured cluster of several atoms that behaves as if it is a single atom. The structure of the superatom imparts characteristic properties unlike that associated with any single element.
In order for metamaterials to be effective they need to have physical features at least as small as the wavelength of the electromagnetic radiation they will interact with.
Properties of Metamaterials
The primary reason metamaterials are of interest is that they have unusually enhanced properties. These properties tend to be enhanced or tailored electromagnetic properties and can include negative refractive indexes, ‘left handed’ materials and transparent materials that would otherwise be opaque.
Although Harry Potter had a special cloak to render himself invisible, it may be metamaterials that lead to real life cloaking devices. Such cloaking devices would interfere with the passage of light near an object. Researchers have already used metamaterials to create a cloaking device that works with microwaves. Other applications for metamaterials include super lenses, next generation handheld electronic devices, advanced solar energy generation, smart window materials and advanced antennas.