SCATTERING AND LOCALIZATION OF SPIN WAVES IN QUASI-2D HEISENBERG FERROMAGNETS WITH EXTENDED FLAT INTERFACE BOUNDARIES

Abstract

The influence of extended flat interface boundaries on the scattering and localization of spin waves in disordered quasi-two-dimensional Heisenberg ferromagnets is studied. The two ferromagnets are considered as two dissimilar semi-infinite slabs in contact, joined together at an extended flat interface between two adjacent planes. The mathematical framework of the matching method is used to analyze both the localization and the scattering phenomena on the extended flat interface boundaries in the harmonic approximation with nearest neighbor magnetic exchange interactions. The energy of spin-wave-localized modes arising from the absence of magnetic translation symmetry in the direction normal to the interface boundaries is determined. The transmission and reflection probabilities, as well as the average transmittance of magnetic excitations across the interface, are calculated in full accordance with the Landauer–Büttiker description of electron transport, and numerical results are presented for the most representative sets of system parameters in a large range of scattering energies. Results show that there are several localized modes, which may be either optical or acoustical modes (depending on the system parameters), and the scattering properties of the system are a strong function of scattering energy and model parameters, which are assumed to be different at the interface compared with those of the bulk.