Magnons in Thin Films

Abstract

In Heisenberg ferromagnetic thin films with {100} surfaces, the spin waves are analyzed in an exact treatment. The bulk and surface modes are separated and discussed. When the number N of parallel layers is finite, space quantization and phase shifts due to the surface perturbation are precised. Magnon specific heat, ferromagnetic resonance and the contribution to the fluctuation of the surface magnetization from the bulk and surface modes are studied in a microscopical way for very thin films. Anomalous variations of specific heat at very low temperature are found to exist. The ferromagnetic resonance is demonstrated to give a detailed study of the surface perturbation. Bulk and surface contributions occur in catalytic effects such as ortho-para conversion.