Mean interface magnon dispersion curves obtained by means of the matching procedure Original Research Article

A theoretical approach based on the matching procedure in the random-phase approximation has been developed to investigate the spin fluctuations dynamics on an interface of the Heisenberg biferromagnetic layers. The two ferromagnetic layers are considered directly coupled by magnetic exchange interactions. No electronic effects are considered. The analytical approach solves for the three-dimensional crystal spin field in the bulk and the interface domain, that arises owing to the reduced of magnetic translation symmetry for the system. The calculations presented here are an application of a theoretical method based on Green functions formalism discussed in previous work. Analytic expressions are obtained for the dispersion relations and spectral intensities of the localized spin-waves and the quantized bulk spin waves near an interface. The effects of varying the bulk-interface coupling exchange near the interface are studied. Also, the condition for the appearance of the acoustic and optical interface modes is discussed. Numerical examples of the modes are given and provide some indication of how the magnon spectrum is affected by interface parameters. These factors influence the energies of localized modes, as well as their frequency, intensity and attenuation.