Spin waves in magnetic double layers with strong antiferromagnetic interlayer exchange coupling: Theory and experiment

Abstract

We present a simple approach based on continuum theory to calculate spin-wave frequencies in thin magnetic multilayers taking into account both the nonuniform static and dynamic magnetizations, which are present in systems with strong interlayer exchange coupling. The calculation includes in-plane static magnetization, the canted and twisted state, bilinear and biquadratic interlayer exchange coupling, and the dynamic dipolar coupling. Therefore, we are able to compute accurate spin-wave frequencies in strongly antiferromagnetic coupled trilayers over a full hysteresis loop. We consider the field dependence of the spin-wave frequencies of an epitaxial Fe(001)/Si-wedge/Fe sample with strong antiferromagnetic coupling measured by Brillouin light scattering and find excellent agreement with the model calculation. The fits of the experimental curves verify the existence of the twisted state and allow determining the coupling constants with high precision.