Localization of magnetic excitations in 1-D quasiperiodic chains: a semi-classical approach

A semi-classical theory is employed to investigate the spin wave spectra and the localization profile of linear quasiperiodic binary superlattices, where one of their components is a ferromagnetic material, the other one being an antiferromagnet. The calculations are carried out for the exchange-dominated regime within the framework of the Heisenberg model, considering a torque equation of motion for the magnetizations. For numerical calculations, we consider the antiferromagnetic material as MnF2, and Fe is the ferromagnetic one. The quasiperiodic arrangement gives rise to localized spin wave spectra, which were observed previously in analogous periodic structures, but only for higher dimensions. Such spectra is analyzed through evaluation of scaling exponents, explicitly demonstrating that our magnetic structure presents fractal features.