Effect of surface spin pinning on the spin-wave propagation in yttrium iron garnet films

The effect of the surface spin pinning on the spin-wave dispersion and propagation characteristics of yttrium iron garnet (YIG) film was studied both experimentally and theoretically. Modification of the spin-wave amplitude frequency response due to the variations of the pinning conditions on the film surfaces and the bias magnetization direction was studied. Ion bombardment with low-energy H⁺ ions was used to control the surface spins pinning. Strong attenuation notches in the spin-wave amplitude-frequency response of ion processed YIG film was treated in terms of dipole hybridization of dispersion branches and appearance of the dipole “gaps” in spin-wave spectrum. The hybridization of spin-wave spectrum was studied for the case of arbitrary magnetization direction and arbitrary surface spin pinning. It has been found that for noninfinite pinning of surface spins, there are magnetization directions for which the gaps in the spectrum are smaller than relaxation frequency, and spin-wave response is smooth