Iron-Iron Exchange Resonance in Ga-Substituted EuIG

Abstract

The iron‐iron exchange resonance in the garnet system Eu₃Fe_5−xGa_xO₁₂ has been studied as a function of x at 4.2°K. In zero field, v=200 cm⁻¹ at x=0 and decreases to zero near the angular momentum compensation point x=1.2. It then rises to a maximum of 9 cm⁻¹ at x=1.35 and falls for larger x. Measurements in a magnetic field indicate a spin flop at the magnetic moment compensation point x=0.75, and an anomalous dispersion in the g factor near x=1.2. These results are in good agreement with a two sublattice model of EuIG for xB.