The Faraday effect at near infra-red wavelengths in rare-earth garnets

Abstract

Measurements are reported of the Faraday effect in five rare-earth garnets at wavelengths between 1 and 4 μm and in the temperature range 77-300°K. In this wavelength range the Faraday effect is associated both with absorption due to electron transitions of optical frequency and with exchange resonance absorption: the effects of the former can be isolated. The observations can be accounted for semi-quantitatively by assuming that the optical absorption band is to be ascribed to transitions pertinent to ferric ions on one crystallographic site, as has been suggested previously. There appears some evidence that the ions involved are in positions of octahedral symmetry.