Magnons in the ferromagnetic Kondo-lattice model

The magnetic properties of the ferromagnetic Kondo-lattice model (FKLM) are investigated. Starting from an analysis of the magnon spectrum in the spin -wave regime, we examine the ferromagnetic stability as a function of the o ccupation of the conduction band n and the strength J of the coupling betwe en the localised moments and the conduction electrons. From the properties of the spin-wave stiffness D the ferromagnetic phase at zero temperature is derived. Using an approximate formula the critical temperature T-c is calc ulated as a function of J and n.