Magnon Spin-Wave & Ferromagnetic Resonance
Exchange J:
1.0
Applied Field H:
0.5
Wavevector k:
3
Spin waves (magnons) in a ferromagnet obey a quadratic dispersion ω(k) = H + 4J·sin²(ka/2) ≈ H + Jk²a² for small k. The uniform precession mode (k=0) is the ferromagnetic resonance frequency ω_FMR = H.