Incorporation of manganese in LPE-grown Mn, YIG films in the presence of Ca 2+ and Ge 4+ ions

Abstract

Abstract The incorporation of manganese into yttrium iron garnet has been investigated in the presence of Ca 2+ and Ge 4+ ions. From the electron probe micro-analysis it was observed that the incorporation of manganese is dependent on the presence of Ca 2+ ions in the melt, but is not influenced by the presence of Ge 4+. The addition of manganese oxide to a YIG melt results in a decrease of the saturation temperature, which is contrary to the expected rise of the saturation temperature on the basis of Van Erk's model on the solubility of garnets. This anomalous effect of manganese on the saturation temperature can be explained by the assumption that the manganese is tetravalent in the melt, so that when Mn 3+ ions are incorporated in the lattice and extra enthalpy term has to be introduced in order to account for the reduction process of the Mn 4+ ions. The absorption coefficients measured at 700 nm can be predicted on the basis of a model in which the total absorption is the sum of single ion contributions. From the absorption data it was also found that the lead ions are divalent in the presence of manganese ions. From the dependence of the lattice constant and the composition of the films the effective ionic radii of the different ions incorporated into the garnet lattice were calculated.