Gyrotropic sphere: Selected examples of resonance spectra

The formal solution to the interaction of a plane electromagnetic wave with a gyrotropic sphere, which was developed by Ford and Werner in the preceding paper, is carried out numerically. We discuss the resonance spectra of two free-carrier systems made gyrotropic by the presence of a dc magnetic field. The first system is a gyrotropic sphere consisting of a single-carrier n-type semiconductor with microwaves incident on the sphere. Such a system displays a series of magnetic and a series of electric dimensional resonances that are associated with all multipole orders of the scattering coefficients. The resonant internal magnetic and displacement field patterns are similar in some respects to their isotropic (Mie) sphere counterparts. The resonant internal electric field patterns, however, differ markedly from those of Mie resonances, since the electric fields in the gyrotropic sphere are restricted, for the most part, to planes perpendicular to the dc magnetic field. The presence of a space-charge density inside the gyrotropic sphere is another departure from the Mie situation, where no space-charge density exists. The second system considered, a compensated two-carrier magnetoplasma sphere (similar, in many respects, to electron-hole drops), represents a stark contrast to the single-carrier magnetoplasma. The structure of the spectra of electric and magnetic dimensional resonances of the compensated system differs in a qualitative manner from that of the single-carrier system. The internal field patterns also reflect this difference and emphasize the importance of the near-surface region in the resonant interaction of a compensated two-carrier magnetoplasma with electromagnetic fields. The disparity in the behavior of the resonance spectra of the two systems underscores the wide range of phenomena that can be described via the Ford and Werner solution of the gyrotropic-sphere problem.