The effect of annealing on sputtered GdIG films

Polycrystalline and single crystal films of GdIG were produced on a variety of substrates by RF sputtering and subsequent annealing. The effects of this annealing on the film properties are discussed. The deviation of the lattice parameters from the ideal value of 12.47 Å was consistent with the strain produced by the mismatch in the thermal expansion coefficients. Optical absorption measurements indicated that the as-sputtered films contained both Fe
²⁺
and Fe
³⁺
ions. The coercive force (
T-T_{c}
) degrees above the compensation point did not depend upon the type of substrate or heat treatment. The temperature dependence of the Faraday rotation was consistent with the presence of a distribution in compensation points throughout the film. Films on YAG were subjected to varying heat treatments, and it was found that the average compensation temperature T
c
of a given film depended on the nature of the anneal. The behavior of the film upon annealing can be explained by a model in which the film successively experiences nucleation and grain growth, oxidation, and Al diffusion.