The dynamic susceptibility and spin waves in layered structures

Abstract

The dynamic susceptibility and spin waves in systems composed of ferromagnetic layers separated by nonmagnetic or nearly nonmagnetic ones are investigated within the framework of tight-binding and random phase approximations. Calculations are based on the multiband model. Layered structures are simulated by changes of the model parameters in the interfilm. The thickness of the spacer is also changed. A reduction of the Coulomb integral in the interfilm as well as an increase in a number of nonmagnetic spacer layers lead to a significant lowering of the effective coupling between magnetic sublayers and therefore strongly influence the spectrum and amplitudes of spin waves. Pairs of modes with very close values of energy are found in the spectrum for low values of U and thick enough nonmagnetic spacer. A distance between two energy levels which correspond to such a pair increases with the energy. The results are well consistent with the ones obtained within the framework of the Heisenberg model.