Quantum mechanical calculations based on an extended Heisenberg model are compared with ferromagnetic resonance experiments on prototype trilayer systems ${\mathrm{Ni}}_7/{\mathrm{Cu}}_n/{\mathrm{Co}}_2/\mathrm{Cu}(001)$ in order to determine and separate for the first time quantitatively the sources of the temperature dependence of interlayer exchange coupling. Magnon excitations are responsible for about 75% of the reduction of the coupling strength from zero to room temperature. The remaining 25% are due to temperature effects in the effective quantum well and the spacer-magnet interfaces.

• Received 6 July 2006

DOI:https://doi.org/10.1103/PhysRevLett.98.057205