Changes in optical absorption in iron garnet films due to impurity incorporation

Abstract

The incorporation of impurities in films of Bi-substituted iron garnets grown by liquid phase epitaxy has been studied by successively adding small amounts of SiO2 and CaCO3 to the melt before film growth. It is found that very small additions of CaCO3 to the melt profoundly influences the optical absorption coefficient and the electrical properties. The impurity absorption ofn-type YIG doped with Si4+ and Pb2+ ions is investigated and its wavelength dependence compared to that ofp-type YIG. The optical transitions involved in the impurity absorption of iron garnets are discussed in terms of transition reaction, photon energy and dependence on the impurity concentration. Depending on the photon energy, one or several transitions may give rise to impurity absorption.