STRONG MAGNETOOPTICAL ENHANCEMENT IN HIGHLY CE-SUBSTITUTED IRON-GARNET FILMS PREPARED BY SPUTTERING

Faraday rotation and ellipticity spectra were measured at photon energies hv = 0.9-4.0 eV for R3-xCexFe5O12 (R = Y, Gd, Yb) films with substitutions up to x = 2.5, expitaxially grown by rf sputtering. The Ce substitution prominently enhances the Faraday effect not only in the IR region at hv = 1.4 eV but also in the UV region at hv = 3.1 eV. Both transitions have a paramagnetic dispersion relation, which are nearly equal in magnitude but opposite in sign. Optical absorption is also induced by a new transition due to Ce3+ at hv = 2.1 eV, which does not enhance Faraday rotation. These electronic transitions may be attributed to charge transfer transition Ce3+ (4f)-Fe3+ (tet.).