Angular-dependent spin-wave modes observations and excitation origins in Yttrium iron garnet thin films

Abstract

We present a study of the dynamic magnetic properties of sputtered-grown YIG films that were subsequently annealed at various temperatures. Our investigation involved the use of the ferromagnetic resonance technique enabled the observation of multimode spin waves spectra. A noticeable increase in the visibility of the multimode spin-wave modes was observed. This finding is ascribed to the rise in surface roughness and anti-site defects in our YIG films as the annealing temperatures increased. We analyzed the correlation between spin-wave modes and the orientation of the magnetic field H. Results showed that a spectrum made up of a variety of spin-wave modes is seen when the applied field H is normal to the film plane. Once the H is tilted from the normal, a critical angle of only one uniform precession mode was detected for some orientations. A fourfold symmetry of the resonance field emerges as H is in the film plane, ascribed to the anisotropy along different crystal orientations of YIG film. Finally, we were able to determine the exchange stiffness constant and distortion parameter by analyzing the spin waves resonance spectra.