Determination of intrinsic FMR line broadening in ferromagnetic (Fe44Co56)77Hf12N11 nanocomposite films

Ferromagnetic nanocomposite (Fe44Co56)77Hf12N11 films were deposited to investigate their intrinsic damping mechanisms due to scattering of itinerant electrons, which carry the magnetic moment of the ferromagnetic transition elements. The films were produced by reactive r.f. magnetron sputtering using a 6 in. Fe37Co46Hf17 target. They were annealed at 400 °C in a static magnetic field, in order to induce in-plane uniaxial anisotropy. Subsequently, the films can be considered as uniformly magnetised. A ferromagnetic resonance frequency (FMR) of around 2.3 GHz could be attained, which was determined by measuring the real and imaginary parts of the frequency dependent permeability up to 5 GHz. The imaginary part, which represents a typical resonance curve, was utilised to obtain its full-width at half-maximum Δfeff (FWHM) for the total damping behaviour characterisation. Thereby, it is possible to extract the intrinsic Gilbert damping parameter αint, which in turn can be decomposed into two additional damping terms αsf and αos allocated to “spin-flip” and “ordinary scattering”, respectively. This result is correlated and discussed in terms of a verified theoretic model, to identify whether damping due to spin-flip scattering and/or ordinary scattering is dominant.