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A theory is developed for dispersion characteristics of spin waves in ferromagnetic films taking into account both dipole-dipole and exchange interactions, crystallographic anisotropy and mixed exchange boundary conditions on the film surfaces. An arbitrary orientation of the external bias magnetic field with respect to the orientation of crystallographic axes and the film normal is assumed. The influence of crystallographic anisotropy on the spin wave spectrum of a ferromagnetic film is discussed. The theoretical results obtained are compared with the results of experiments performed in yttrium-iron garnet (YIG) and Mn-ferrospinel films.

Solitons are large-amplitude, spatially confined wave packets in nonlinear media. They occur in a wide range of physical systems, such as water surfaces, optical fibres, plasmas, Bose-Einstein condensates and magnetically ordered media. A distinguishing feature of soliton behaviour that is common to all systems, is that they propagate without a change in shape owing to the stabilizing effect of the particular nonlinearity involved. When the propagation path is closed, modes consisting of one or several solitons may rotate around the ring, the topology of which imposes additional constraints on their allowed frequencies and phases. Here we measure the mode spectrum of spin-wave solitons in a nonlinear active ring constructed from a magnetic ferrite film. Several unusual symmetry-breaking soliton-like modes are found, such as 'Möbius' solitons, which break the fundamental symmetry of 2pi-periodicity in the phase change acquired per loop: a Möbius soliton needs to travel twice around the ring to meet the initial phase condition.

A dual, electric and magnetic field tunable microwave phase shifter based on the propagation of hybrid spin-electromagnetic waves in a ferrite-ferroelectric bilayer is discussed. The bilayer consists of a single-crystal yttrium iron garnet film and a ceramic barium strontium titanate slab. The electrical tunability of the differential phase shift Δφ is achieved through the application of a voltage across barium strontium titanate. An insertion loss of 20dB and a continuously variable Δφ as high as 650° in the frequency range of 4.5–8GHz are measured.

An electric current controlled spin-wave logic gate based on a width-modulated dynamic magnonic crystal is realized. The device utilizes a spin-wave waveguide fabricated from a single-crystal Yttrium Iron Garnet film and two conducting wires attached to the film surface. Application of electric currents to the wires provides a means for dynamic control of the effective geometry of the waveguide and results in a suppression of the magnonic band gap. The performance of the magnonic crystal as an AND logic gate is demonstrated.

The self-generation of single, fundamental, stable, spin-wave-envelope black and gray dark solitons has been realized for the first time. These solitons were generated from microwave magnetostatic surface waves (MSSWs) propagated in an in-plane magnetized yttrium iron garnet film MSSW delay line in a resonant ring. These fundamental dark solitons were made possible by a new and general filtering technique for a high gain nonlinear resonant ring. The amplitude and phase profiles together with the power spectra of the self-generated microwave pulses confirm their fundamental dark soliton nature.

Formation of dipolar spin-wave (SW) (or magtietostatic wave) envelope solitons was observed in yttrium iron garnet films with unpinned surface spins under pulsed excitation. The solitons were formed in the spectral regions of relatively low dispersion from the short rectangular input pulses (T 4-50 ns). With the increase of the duration and/or amplitude of the input pulse, the multisoliton regime of SW propagation was registered. A theoretical interpretation of the observed nonlinear phenomena in terms of a nonlinear Schrodinger equation model with dissipation is given.(2tt/TV ) '(8'to/8k ') » to", I UI'»co, /(8to/8I UI'), (2) (3) where T is the duration of the in ut pulse, Vs 8at/8k is the wave group velocity, 8 co/8k is the wave dispersion, 8to/8IUI characterizes the wave nonlinearity, U is the dimensionless amplitude of the envelope of the propagating wave, and co"is the dissipation parameter of the propagating wave. For the case of spin-wave (SW) propagating in the ferromagnetic film (FF) the dimensionless amplitude of the SW envelope U is determined bywhere m",my are the components of the variable magnetization m and 4trMo (Mollz) is the equilibrium magnetization. The SW dissipation parameter is equal to to, 2try~k, where ) 2.8 MHz/Oe and AHk is the half-linewidth of ferromagnetic resonance in ferromagnetic film in Oe.It is worth noting that condition (3) in FF also means that the amplitude of the propagating SW should be greater than the threshold of the four-wave parametric decay process (second-order Suhl process ) toq+tol, =tot"+tot, "q;-(k;k) «k, i -1, 2, . . . , (5) which is responsible for the SW nonlinearity when the low-threshold three-wave decay processes (first-order Envelope solitons are stable nonlinear excitations that emerge during finite-amplitude wave pulse propagation in the dispersive media as a result of competition between the spreading effect of dispersion and the self-steepening effect of nonlinearity when both these effects are much stronger than the effect of dissipation. The conditions of envelope soliton formation in nonlinear dispersive media with dissipation are as follows:' (i) The Lighthill criterion which requires nonlinearity and dispersion to have opposite signs (8' N/8k')(8N/8 I UI') &0;(ii) the dissipation criteria that require the influence of dispersion and nonlinearity on the input pulse profile to be much greater than the influence of dissipation Suhl processes) COg COg, + Ng, (5a) are prohibited by conservation laws.There are two ways to satisfy the criterion (2): to find regions in the SW spectrum of the FF where dispersion 8 to/8k is sufficiently high, or to reduce the duration T of the input pulse when working in the spectral regions of relatively low dispersion.The first way was used in our work ' and led to the first experimental observation of dipole-exchange SW envelope solitons (T, 120 ns) in the regions of high dispersion near the dipole "gaps" in the dipole-exchange SW spectrum of a perpendicularly magnetized yttrium iron garnet (YIG) film with pinned sur...