Verba R. Microwave properties of artificial magnonic crystals based on arrays of magnetic nanoelements

The thesis is devoted to the investigation of the eigenoscillations and microwave properties of artificial magnonic crystals (MC) based on arrays of magnetic nanoelements. The theory of collective eigenoscillations of an array of magnetodipolarly coupled magnetic nanodots was generalized to the case of an arbitrary nanodots and lattice geometry. The orthogonality relation for MC's eigenmodes was derived. The theory allows one to calculate spin waves (SW) spectra of MC, the dissipation rates of eigenmodes and the spectra of electromagnetic radiation absorption by MC. The influence of diverse kind of defects on resonance properties of MC was investigated; it was shown, that a point defect may lead to the appearance of several localized in its vicinity modes. The necessary conditions for the frequency nonreciprocity of SWs propagating in MC was derived. The possibility of controllable switching of the stationary state of MC, consisting of identical nanodots, by magnetic field pulses with typical duration about several tens of nanoseconds was demonstrated; the relalation between statistic and microwave properties of MC and field pulse parameters was found.