The high frequency behavior beyond 1 GHz of a Fe–Co–N film and a NiFeFe–Co–N film [NiFe stands for Ni81Fe19(wt. %)], shown as promising magnetic write head materials previously, has been investigated using a pulse inductive microwave magnetometer in this work. The NiFFe–Co–N film, which has a smaller dispersion angle (∼0.8°) than the Fe–Co–N film (∼2°), shows a smaller damping parameter and a higher ferromagnetic resonance frequency when longitudinally biased. When the Fe–Co–N film is transversely biased, the damping parameter of the Fe–Co–N film shows a diffuse peak at a transverse field of 1.76 kA/m (22 Oe), and its ferromagnetic resonance frequency shows a small local maximum at 1.76 kA/m (22 Oe). In contrast, the damping parameter of the NiFeFe–Co–N film shows a sharp peak at a transverse field of 1.4 kA/m (18 Oe), and its ferromagnetic resonance frequency displays a sharp local maximum also at a transverse field of 1.4 kA/m (18 Oe) too, which is very close to the dc anisotropy field. The sharp peak in the ferromagnetic resonance frequency and the damping parameter of the NiFeFe–Co–N film is due to the generation of a higher order (very close to the second order) ferromagnetic absorption when the ac field is large compared to the net in-plane dc magnetic field. © 2003 American Institute of Physics.