Adjusted oscillator strength matching for hybrid magnetic and electric excitations in Dy3Fe5O12 garnet

Far-infrared spectra of magnetodielectric Dy3Fe5O12 garnet were studied using a combination of transmittance, reflectivity, and rotating analyzer ellipsometry. In addition to purely dielectric and magnetic modes, we observed several hybrid modes with a mixed magnetic and electric dipole activity. Using 4 x 4 matrix formalism for materials with mu(omega) not equal 1, we modeled the experimental optical spectra and determined the far-infrared dielectric and magnetic permeability functions. The matching condition mu(omega(h))S-e = epsilon(omega(h))S-m for the oscillator strengths S-e(m) explains the observed vanishing of certain hybrid modes omega(h) in reflectivity.