Temperature Variation of the Spin-Wave Dispersion Relation

This is the authors' abstract. We don't add key points for this paper.

The spin-wave dispersion relation, including the quartic term, has been measured at 61.8 Gc/sec between 4° and 300°K by spin-wave resonance in Permalloy films. Both the quadratic and the quatric terms vary as T52 up to 80°K and approximately as T32 up to room temperature. This is the same behavior previously reported for the quadratic term using a different Permalloy film at 10 Gc/sec. The long-range exchange interaction 〈ρ2〉=ΣJ(r)r4/ ΣJ(r)r2, where J(r) is the exchange integral between spins a distance r apart, has been obtained as a function of temperature from the ratio of the coefficient of the quatric term to the coefficient of the quadratic term.