M. Mruczkiewicz and M. Krawczyk

Phys. Rev. B 94, 024434 (2016)

We study the effect of surface-induced Dzyaloshinskii-Moriya interaction (DMI) on the ferromagnetic resonance (FMR) spectrum of thickness-modulated one-dimensional magnonic crystals and isolated stripes. The DMI is found to substantially increases the intensity of absorption peaks and shifts the frequencies of the laterally quantized modes. The role of the DMI is determined by analyzing the amplitude and phase distributions of dynamic magnetic excitations calculated with frequency- and time-domain calculation methods. We propose experimentally realizable magnonic crystals and confined structures with multiple FMR absorption peaks. The frequency or magnetic field separation between FMR lines is exploited to propose a method for estimation of the DMI strength.

Fig.1. FMR frequency spectrum of the studied magnonic crystal (Co film with modulated thickness); ${\mu }_0{H}_0=100$ mT. Results of FDTD simulations for $D=0$ mJ/$m^2$ (blue dashed line) and $D=1$ mJ/$m^2$ (green solid line). The vertical lines indicate the eigenmode resonance position calculated with FDFEM. Due to the symmetry of the modes in the structure with $D=0$ only one mode around 18 GHz is observed in FDTD simulations.