Candidates for mu < 0, epsilon < 0 nanostructures

Recent interest has been generated in composite materials for which both th e dielectric constant and the magnetic permeability are negative. These com posites behave as if they possess a negative index of refraction, although the broader, less specific adjective "left-handed" has also been applied to them. Such composites possess two sets of structures which axe separately responsible for the negative epsilon and mu. However, materials having a ne gative mu are common in the microwave frequency range and such a material c an replace one set of structures in the composite. An example of a simple c omposite is a YIG medium (mu <0) penetrated by sets of metallic strips or w ires which give rise a negative dielectric constant in the appropriate freq uency range. The index of refraction of the composite can be modulated by a djusting the applied magnetic field.