A study of the Faraday effect in yttrium aluminium garnets doped with cerium

Abstract

Calculations of the Faraday rotation (FR) and magnetic circular dichroism spectra in the wavelength region between 300 nm and 650 nm caused by the Ce3+ ions in the Ce substituted aluminium garnets (YAG) based on the quantum theory are presented. The Faraday effect contributed by the Ce3+ ions is caused mainly by the intraionic electrical dipole transitions between the 4f and 5d configurations. The effect of the crystal field (CF) and spin orbit coupling on the Faraday effect has been discussed. The CF upon the Ce3+ ions doped in garnets depends strongly on the nature of the next-nearest neighbors. The CF upon the Ce3+ ions in YAG is weaker than that in yttrium iron garnets (YIG). Therefore, compared with Ce: YIG, the anomalous rotatory dispersions occur at higher frequencies. The shape of the FR spectrum caused by the Ce3+ ions in YAG is different from that caused by the Ce3+ ions in YIG. An explanation of this difference is given. The influence of the mixing of different multiplets of the ground configuration on the Faraday effect is discussed. Such mixing is one of the causes which make the magneto-optical coefficient vary with temperature.