Spin-wave resonance in Co/Pd magnetic multilayers and NiFe/Cu/NiFe three-layered films

The spectrum of standing spin waves has been detected by the ferromagnetic resonance method in NiFe(740 Å)/Cu/NiFe(740 Å) three-layered film structure in the perpendicular configuration for the copper thickness d _Cu ≤ 30 Å. At thicknesses d _Cu > 30 Å, the resonance absorption curve is a superposition of two spinwave resonance spectra from individual ferromagnetic NiFe layers. For Co/Pd multilayer films, united spinwave responance spectra have also been observed at thicknesses of the paramagnetic palladium layer up to d _Pd < 30 Å. The partial exchange stiffness has been calculated for a spin wave propagating across the Pd layer (A _Pd = 0.1 × 10⁻⁶ erg/cm). This value is always positive (up to the critical thickness of the palladium interlayer d _Pd < d _c) or equal to zero (d _Pd > d _c).