Contribution of Magnons to the Magnetic Properties of Fe/GaAs Thin Films

In this work, we investigate the magnetic properties of the Fe/GaAs superlattice for various thicknesses of the iron magnetic layer. The study was performed within the framework of the Heisenberg model. The excitation spectrum and the magnetization per spin were calculated using the retarded Green function method. We have highlighted that the excitation spectrum splits into two sub-bands of different characteristics, which we have attributed to surface and bulk magnons. Comparison between the calculations and the experimental measurements of magnetization per spin allowed us to obtain a very satisfactory estimation of the exchange integrals. The combined effects of surface anisotropy and dipolar interaction were also investigated through numerical analysis.