FMR in the anisotropy field consider a spherical specimen of a uniaxial ferromagnetic crystal with an anisotropy energy density of the form U K K sin 2 , where is the angle between the magnetization and the z axis We assume that K is positive Show that the ferromagnetic resonance frequency in an ex...

For small 9 we have U KO Now the magnetic energy density UBM cos 0 BM ...

FMR in the anisotropy field consider a spherical specimen of a uniaxial ferromagnetic crystal with an anisotropy

Question:

FMR in the anisotropy field consider a spherical specimen of a uniaxial ferromagnetic crystal with an anisotropy energy density of the form U_K = K sin² θ, where θ is the angle between the magnetization and the z axis. We assume that K is positive. Show that the ferromagnetic resonance frequency in an external magnetic field B₀z is w₀ = γ(B₀ + B_A), where B_A = 2K/M_s.