Anisotropy dispersion effects on the high frequency behavior of soft magnetic Fe–Co–N thin films

The high frequency behavior beyond 1 GHz of a Fe–Co–N film and a NiFe\Fe–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 NiF\Fe–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 NiFe\Fe–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 pea...