arXiv subjects

A. A. Serga

Publications and source records attributed to A. A. Serga.

45 records · Page 3Linked to original sources

arXiv2008

Probing of a parametrically pumped magnon gas with a non-resonant packet of traveling spin waves

The magnon gas created by spatially localized longitudinal parametric pumping in an yttrium-iron-garnet film is probed by a traveling packet of spin waves non-resonant with the pumping field. The analysis of the influence of the magnon gas on the amplitude and phase of the propagating spin waves allows to determine characteristic properties of the parametrically pumped magnon gas. A simple theoretical model is proposed from which the magnon density in the pumping region is calculated.

cond-mat.other↗

arXiv2008

Parametrically-stimulated recovery of a microwave signal using standing spin-wave modes of a magnetic film

The phenomenon of storage and parametrically-stimulated recovery of a microwave signal in a ferrite film has been studied both experimentally and theoretically. The microwave signal is stored in the form of standing spin-wave modes existing in the film due to its finite thickness. Signal recovery is performed by means of frequency-selective amplification of one of these standing modes by double- requency parametric pumping process. The time of recovery, as well as the duration and magnitude of the recovered signal, depend on the timing and amplitudes of both the input and pumping pulses. A mean-field theory of the recovery process based on the competitive interaction of the signal-induced standing spin-wave mode and thermal magnons with the parametric pumping field is developed and compared to the experimental data.

cond-mat.other↗

arXiv2008

Formation of guided spin-wave bullets in ferrimagnetic film stripes

The formation of quasi-2D nonlinear spin-wave eigenmodes in longitudinally magnetized stripes of a ferrimagnetic film, so-called guided spin-wave bullets, was experimentally observed by using time- and space-resolved Brillouin light scattering spectroscopy and confirmed by numerical simulation. They represent stable spin-wave packets propagating along a waveguide structure, for which both transversal instability and interaction with the side edges of the waveguide are important. The experiments and the numerical simulation of the evolution of the spin-wave excitations show that the shape of the formed packets and their behavior are strongly influenced by the confinement conditions. The discovery of these modes demonstrates the existence of quasi-stable nonlinear solutions in the transition regime between one-dimensional and two-dimensional wave packet propagation.

cond-mat.other↗

arXiv2008

Scattering of backward spin waves in a one-dimensional magnonic crystal

Scattering of backward volume magnetostatic spin waves from a one-dimensional magnonic crystal, realized by a grating of shallow grooves etched into the surface of an yttrium-iron garnet film, was experimentally studied. Rejection frequency bands were clearly observed. The rejection efficiency and the frequency width of the rejection bands increase with increasing groove depth. A theoretical model based on the analogy of a spin-wave film-waveguide with a microwave transmission line was used to interpret the obtained experimental results.

cond-mat.mtrl-sci↗

arXiv2008

Phase reciprocity of spin-wave excitation by a microstrip antenna

Using space-, time- and phase-resolved Brillouin light scattering spectroscopy we investigate the difference in phase of the two counterpropagating spin waves excited by the same microwave microstrip transducer. These studies are performed both for backward volume magnetostatic waves and magnetostatic surface waves in an in-plane magnetized yttrium iron garnet film. The experiments show that for the backward volume magnetostatic spin waves (which are reciprocal and excited symmetrically in amplitude) there is a phase difference of $π$ associated with the excitation process and thus the phase symmetry is distorted. On the contrary, for the magnetostatic surface spin waves (which are non-reciprocal and unsymmetrical in amplitude) the phase symmetry is preserved (there is no phase difference between the two waves associated with the excitation). Theoretical analysis confirms this effect.

cond-mat.other↗

arXiv2008

Microwave spectral analysis by means of non-resonant parametric recovery of spin-wave signals in a thin magnetic film

We report on the storage and non-resonant parametric recovery of microwave signals carried by a dipolar surface spin-wave pulse in a thin ferrimagnetic film. The information about the intensity of the spectral components of the signal within a narrow frequency band is saved due to the excitation of a dipolar-exchange standing spin-wave mode across the film thickness and is afterwards restored by means of parametric amplification of this mode. The intensity of the restored signal measured for varying shifts between the signal carrier frequency and half of the pumping frequency, which is equal to the frequency of the standing mode, reveals information about the entire frequency spectrum of the input microwave signal.

cond-mat.mtrl-sci↗

arXiv2007

Realization of XNOR and NAND spin-wave logic gates

We demonstrate the functionality of spin-wave logic XNOR and NAND gates based on a Mach-Zehnder type interferometer which has arms implemented as sections of ferrite film spin-wave waveguides. Logical input signals are applied to the gates by varying either the phase or the amplitude of the spin waves in the interferometer arms. This phase or amplitude variation is produced by Oersted fields of dc current pulses through conductors placed on the surface of the magnetic films.

cond-mat.other↗

arXiv2007

Resonant scattering of spin waves from a region of inhomogeneous magnetic field in a ferromagnetic film

The transmission of a dipole-dominated spin wave in a ferromagnetic film through a localised inhomogeneity in the form of a magnetic field produced by a dc current through a wire placed on the film surface was studied experimentally and theoretically. It was shown that the amplitude and phase of the transmitted wave can be simultaneously affected by the current induced field, a feature that will be relevant for logic based on spin wave transport. The direction of the current creates either a barrier or well for spin wave transmission. The main observation is that the current dependence of the amplitude of the spin wave transmitted through the well inhomogeneity is non-monotonic. The dependence has a minimum and an additional maximum. A theory was constructed to clarify the nature of the maximum. It shows that the transmission of spin waves through the inhomogeneity can be considered as a scattering process and that the additional maximum is a scattering resonance.

cond-mat.mtrl-sci↗

arXiv2007

Formation of quasi-solitons in transverse confined ferromagnetic film media

The formation of quasi-2D spin-wave waveforms in longitudinally magnetized stripes of ferrimagnetic film was observed by using time- and space-resolved Brillouin light scattering technique. In the linear regime it was found that the confinement decreases the amplitude of dynamic magnetization near the lateral stripe edges. Thus, the so-called effective dipolar pinning of dynamic magnetization takes place at the edges. In the nonlinear regime a new stable spin wave packet propagating along a waveguide structure, for which both transversal instability and interaction with the side walls of the waveguide are important was observed. The experiments and a numerical simulation of the pulse evolution show that the shape of the formed waveforms and their behavior are strongly influenced by the confinement.

nlin.PS↗