Spin waves span a broad range of frequencies from hundreds of MHz up to tens of GHz with the respective wavelengths ranging from micrometers to nanometers. Moreover, the spin wave spectrum can be tuned by external magnetic field and depends on the magnetization configuration. These properties are desirable for applications in microwave and information processing technologies, and are in focus of magnonics. We present results of our studies which show tailoring of the spin wave spectra in ferromagnetic thin films with periodicity along one and two directions. We describe basics of the magnonic band structure formation, opening magnonic band gaps, and selected methods of its induction in thin ferromagnetic films: by antidots etching, bi-component structures, magnetic domains or dynamic dipolar coupling. We pay attention on effect of nonreciprocity in the magnonic band structure and describe the mechanisms of its appearing. The described properties of magnonic crystals are used to propose directional couplers for spin waves.
We acknowledge the financial NCN project UMO-2012/07/E/ST3/00538 and the EU Horizon 2020 GA No 644348 (MagIC).
P. Graczyk and M. Krawczyk, Coupled-mode theory for the interaction between acoustic waves and spin waves in magnonic-phononic crystals: Propagating magnetoelastic waves, Phys. Rev. B 96, 024407 (2017).
C. Banerjee, P. Gruszecki, J. W. Klos, O. Hellwig, M. Krawczyk, and A. Barman, Magnonic band structure in a Co/Pd stripe domain system investigated by Brillouin light scattering and micromagnetic simulations, Phys. Rev. B 96, 024421 (2017).
M. Mruczkiewicz, P. Graczyk, P. Lupo, A. Adeyeye, G. Gubbiotti, M. Krawczyk, Spin wave nonreciprocity and magnonic band structure in thin permalloy film induced by dynamical coupling with an array of Ni stripes, Phys. Rev. B 96, 104411 (2017).
P. Graczyk, M. Zelent, and M. Krawczyk, Co- and contra-directional vertical coupling between ferromagnetic layers with grating for short-wavelength spin wave generation, New J. Phys. (2018). In press.