Temperature dependence of ferromagnetic resonance in permalloy/NiO exchange-biased films

The temperature dependencies of the ferromagneticresonance (FMR) linewidth and the resonance field-shift have beeninvestigated for NiO/NiFe exchange-biased bilayers from 78 K to 450 K. A broad maximum in the linewidth of 500 Oe, solely due to theexchange-bias, is observed at ≈150 K when the magneticfield is applied along the film plane. When the magnetic field isapplied perpendicular to the film plane, the maximum in thelinewidth is less pronounced and amounts to 100 Oe at the sametemperature. Such a behavior of the FMR linewidth is accompaniedwith a monotonic increase in the negative resonance field-shiftwith decreasing temperature. Our results are compared with theprevious experimental FMR and Brillouin light scattering data forvarious ferromagnetic/antiferromagnetic (FM/AF) structures, andsuggest that spin dynamics (spin-wave damping and anomalousresonance field-shift) in the FM/AF structures can be described ina consistent way by a single mechanism of the so-calledslow-relaxation.