Correlation length and negative phase velocity in isotropic dielectric-magnetic materials

摘要

A composite material comprising randomly distributed spherical particles oftwo different isotropic dielectric-magnetic materials is homogenized using thesecond-order strong-property-fluctuation theory in the long-wavelengthapproximation. Whereas neither of the two constituent materials by itselfsupports planewave propagation with negative phase velocity (NPV), thehomogenized composite material (HCM) can. The propensity of the HCM to supportNPV propagation is sensitive to the distributional statistics of theconstituent material particles, as characterized by a two--point covariancefunction and its associated correlation length. The scope for NPV propagationdiminishes as the correlation length increases.