  The inertial dynamics of magnetization in a ferromagnet is investigated
theoretically. The analytically derived dynamic response upon microwave
excitation shows two peaks: ferromagnetic and nutation resonances. The exact
analytical expressions of frequency and linewidth of the magnetic nutation
resonance are deduced from the frequency dependent susceptibility determined by
the inertial Landau-Lifshitz-Gilbert equation. The study shows that the
dependence of nutation linewidth on the Gilbert precession damping has a
minimum, which becomes more expressive with increase of the applied magnetic
field.
