Frequency- and time-resolved measurements of FeTaN films with longitudinal bias fields

The high frequency characteristics of 100 nm FeTaN films have been studied by using both time-resolved inductive techniques and frequency-resolved permeability measurements. Experiments performed as a function of longitudinal bias fields from 120 to 2400 A/m (1.5-30 Oe) showed precessional frequencies from 1.3 to 2.5 GHz, initial permeabilities from 1600 to 500, and damping constants alpha=0.013 to 0.0045. It is illustrated that the magnetization precessional data obtained from the time-resolved inductive technique can be Fourier transformed to the frequency domain to give the real and imaginary components of a permeability spectrum; this spectrum compares well with data obtained from frequency-resolved permeability measurements. It is also demonstrated that accurate values of the damping constant alpha can only be determined from permeameters whose bandwidth is two to three times the ferromagnetic resonance frequency of the material to be measured. (C) 2000 American Institute of Physics. [S0021-8979(00)87808-1].