The absorption spectra of Y3Fe5O12 and Y3Ga5O12:Fe3+ to 5.5 eV

The absorption spectrum of Y3Fe6012 (YIG) is obtained to 40000 cm−1 and analysed by Gaussian fitting to the spectrum of ε0 obtained from the absorption data and the known refractive index behaviour. The energies of the major components agree well with those obtained in Y3Ga5O12:Fe3+. Comparison of the spectra of Y3Fe0.09Ga5.O12 and YIG indicates that all transitions below 35000 cm−1 involve Fe3+ pairs and that the first charge transfer transition between the oxygen 2p band and the iron d‐like bands occurs at 35600 and 37400 cm−1 in YIG and Y3Fe0.09Ga4.91O12 respectively with an oscillator strength of approximately 0.1. An assignment is forwarded for the pair bands in terms of intersublattice Fe3+ charge transfer transitions with reasonable agreement between the expected and observed energies and intensities. An example of the use of the density of states plot, obtained from the analysis, to explain the features of impurity absorption spectra in YIG is given for YIG:Si.