172 research outputs found
Non-resonant wave front reversal of spin waves used for microwave signal processing
It is demonstrated that non-resonant wave front reversal (WFR) of spin-wave
pulses caused by pulsed parametric pumping can be effectively used for
microwave signal processing. When the frequency band of signal amplification by
pumping is narrower than the spectral width of the signal, the non-resonant WFR
can be used for the analysis of the signal spectrum. In the opposite case the
non-resonant WFR can be used for active (with amplification) filtering of the
input signal.Comment: 4 pages, 3 figure
Field-induced transition from parallel to perpendicular parametric pumping for a microstrip transducer
Microstrip transducers used for the excitation of spin waves in magnetic
films possess two characteristic properties: high spatial localization of the
microwave magnetic field and the presence of field components parallel and
perpendicular to the bias field.
Here, the effects of these features on the process of parametric pumping are
presented. By microwave measurements of the spin-wave instability threshold a
transition from parallel pumping to perpendicular pumping at the critical field
with the minimal threshold is observed. This transition is
accompanied by a sharp threshold increase above the critical field due to the
spatial confinement of the pump region.Comment: 4 pages, 2 figure
Dispersion Characteristics of Spin-Electromagnetic Waves in Planar Multiferroic Structures with Coplanar Transmission Line
Introduction. The distinctive feature of a coplanar transmission line with thin ferrite and ferroelectric films is the absence of undesirable irregularities in dispersion for relatively low frequencies when the wavelength approaches the thickness of ferroelectric layer, in contrast to the open ferrite-ferroelectric wave-guiding structure without metallization.Aim. The purpose of this paper is twofold: (i) to develop a theory of the wave spectra in the multiferroic structures based on the coplanar lines; (ii) using this theory to find ways to enhance the electric tuning range.Materials and methods. The dispersion relation for spin-electromagnetic waves was derived through analytical solution of the full set of the Maxwell's equations utilizing a method of approximate boundary conditions.Results. A theory of spin-electromagnetic wave spectrum has been developed for the thin-film ferrite-ferroelectric structure based on a coplanar transmission line. According to this theory, dispersion characteristics of the spin-electromagnetic waves were described and analyzed for different parameters of the structure. The obtained results show that the investigated structure demonstrates a dual electric and magnetic field tunability of wave spectra. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the width of the central metal strip.Conclusion. The distinctive features of the proposed coplanar waveguides are the thin-film planar topology and dual tunability of the wave spectra. All these advantages make the proposed structures perspective for development of new microwave devices.Introduction. The distinctive feature of a coplanar transmission line with thin ferrite and ferroelectric films is the absence of undesirable irregularities in dispersion for relatively low frequencies when the wavelength approaches the thickness of ferroelectric layer, in contrast to the open ferrite-ferroelectric wave-guiding structure without metallization.Aim. The purpose of this paper is twofold: (i) to develop a theory of the wave spectra in the multiferroic structures based on the coplanar lines; (ii) using this theory to find ways to enhance the electric tuning range.Materials and methods. The dispersion relation for spin-electromagnetic waves was derived through analytical solution of the full set of the Maxwell's equations utilizing a method of approximate boundary conditions.Results. A theory of spin-electromagnetic wave spectrum has been developed for the thin-film ferrite-ferroelectric structure based on a coplanar transmission line. According to this theory, dispersion characteristics of the spin-electromagnetic waves were described and analyzed for different parameters of the structure. The obtained results show that the investigated structure demonstrates a dual electric and magnetic field tunability of wave spectra. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the width of the central metal strip.Conclusion. The distinctive features of the proposed coplanar waveguides are the thin-film planar topology and dual tunability of the wave spectra. All these advantages make the proposed structures perspective for development of new microwave devices
Theory for a dissipative droplet soliton excited by a spin torque nanocontact
A novel type of solitary wave is predicted to form in spin torque oscillators
when the free layer has a sufficiently large perpendicular anisotropy. In this
structure, which is a dissipative version of the conservative droplet soliton
originally studied in 1977 by Ivanov and Kosevich, spin torque counteracts the
damping that would otherwise destroy the mode. Asymptotic methods are used to
derive conditions on perpendicular anisotropy strength and applied current
under which a dissipative droplet can be nucleated and sustained. Numerical
methods are used to confirm the stability of the droplet against various
perturbations that are likely in experiments, including tilting of the applied
field, non-zero spin torque asymmetry, and non-trivial Oersted fields. Under
certain conditions, the droplet experiences a drift instability in which it
propagates away from the nanocontact and is then destroyed by damping.Comment: 15 pages, 12 figure
Generation of spin-wave dark solitons with phase engineering
We generate experimentally spin-wave envelope dark solitons from rectangular
high-frequency dark input pulses with externally introduced phase shifts in
yttrium-iron garnet magnetic fims. We observe the generation of both odd and
even numbers of magnetic dark solitons when the external phase shift varies.
The experimental results are in a good qualitative agreement with the theory of
the dark-soliton generation in magnetic films developed earlier [Phys. Rev.
Lett. 82, 2583 (1999)].Comment: 6 pages, including 7 figures, submitted to Phys. Rev.
Formation of Random Dark Envelope Solitons from Incoherent Waves
This letter reports experimental results on a new type of soliton: the random
temporal dark soliton. One excites an incoherent large-amplitude propagating
spin-wave packet in a ferromagnetic film strip with a repulsive, instantaneous
nonlinearity. One then observes the random formation of dark solitons from this
wave packet. The solitons appear randomly in time and in position relative to
the entire wave packet. They can be gray or black. For wide and/or very strong
spin-wave packets, one also observes multiple dark solitons. In spite of the
randomness of the initial wave packets and the random formation processes, the
solitons show signatures that are found for conventional coherent dark
solitons.Comment: 10 pages, 4 figures, double-spaced preprint forma
ΠΠ½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΠ΅ΠΎΡΠΈΡ Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΈ ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ Π²ΠΎΠ»Π½ ΡΠ΅Π³ΡΠ»ΡΡΠ½ΡΡ ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄ΠΎΠ²
A method for analysis of dispersion characteristics of guided optical modes propagating in the optical waveguides with small cross-sections is proposed. The method is based on introduction of a correction factor for a longitudinal wavenumber of propagating modes. The correction factor arises when a cross-section of the basic rectangular waveguide is subjected to perturbation. The electromagnetic field distributions along with the mode longitudinal wavenumber are found by means of variable separation method. The longitudinal wavenumber correction factor is analytically calculated in terms of coupled mode theory. The combined use of the complete set of equations of electrodynamics together with the concept of effective sources gives rise to the correction factor in the form of an intermodal coupling coefficient. It is pointed out that the coupling coefficient consists of two components, namely bulk and surface, owing to accurate account of the electrodynamics boundary conditions. Using the method proposed, the dispersion characteristics of the fundamental modes propagating in the practically employed optical waveguides having a trapezoidal cross-section are calculated. An impact of the waveguide cross-section shape to cladding dielectric constant ratio on the mode dispersion characteristics is analyzed. The necessity to take into consideration an imperfection of the waveguide cross-section in a wide range of operating wavelengths is demonstrated.Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½ ΠΌΠ΅ΡΠΎΠ΄ Π°Π½Π°Π»ΠΈΠ·Π° Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΎΠ½Π½ΡΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ Π½Π°ΠΏΡΠ°Π²Π»ΡΠ΅ΠΌΡΡ
ΠΌΠΎΠ΄ Π² ΡΠ΅Π³ΡΠ»ΡΡΠ½ΡΡ
ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π°Ρ
ΠΌΠ°Π»ΠΎΠ³ΠΎ ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ. ΠΠ΅ΡΠΎΠ΄ ΠΎΡΠ½ΠΎΠ²Π°Π½ Π½Π° Π²Π²Π΅Π΄Π΅Π½ΠΈΠΈ ΠΏΠΎΠΏΡΠ°Π²ΠΎΠΊ ΠΊ ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½ΠΎΠΌΡ Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠΌΡ ΡΠΈΡΠ»Ρ ΠΌΠΎΠ΄ ΠΏΡΡΠΌΠΎΡΠ³ΠΎΠ»ΡΠ½ΠΎΠ³ΠΎ Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π°, Π²ΡΠ±ΡΠ°Π½Π½ΠΎΠ³ΠΎ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π±Π°Π·ΠΎΠ²ΠΎΠ³ΠΎ, ΠΏΡΠΈ ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΠΈ ΡΠΎΡΠΌΡ Π΅Π³ΠΎ ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ. Π Π°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ»Ρ ΠΈ ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½ΠΎΠ³ΠΎ Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ³ΠΎ ΡΠΈΡΠ»Π° Π±Π°Π·ΠΎΠ²ΠΎΠ³ΠΎ Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π° ΡΠ°ΡΡΡΠΈΡΡΠ²Π°ΡΡΡΡ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΡΠ°Π·Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
. ΠΠΎΠΏΡΠ°Π²ΠΊΠ° ΠΊ ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½ΠΎΠΌΡ Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠΌΡ ΡΠΈΡΠ»Ρ ΡΠ°ΡΡΡΠΈΡΡΠ²Π°Π΅ΡΡΡ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΈ Π² ΡΠ΅ΡΠΌΠΈΠ½Π°Ρ
ΡΠ΅ΠΎΡΠΈΠΈ ΡΠ²ΡΠ·Π°Π½Π½ΡΡ
ΠΌΠΎΠ΄. Π£ΠΊΠ°Π·Π°Π½Π½Π°Ρ ΠΏΠΎΠΏΡΠ°Π²ΠΊΠ° Π² Π²ΠΈΠ΄Π΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° ΠΌΠ΅ΠΆΠΌΠΎΠ΄ΠΎΠ²ΠΎΠΉ ΡΠ²ΡΠ·ΠΈ Π²ΠΎΠ·Π½ΠΈΠΊΠ°Π΅Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠΎΠ²ΠΌΠ΅ΡΡΠ½ΠΎΠ³ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠ»Π½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ ΡΡΠ°Π²Π½Π΅Π½ΠΈΠΉ ΠΠ°ΠΊΡΠ²Π΅Π»Π»Π° ΠΏΡΠΈ Π²Π²Π΅Π΄Π΅Π½ΠΈΠΈ ΠΏΠΎΠ½ΡΡΠΈΡ ΠΎΠ± ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠ°Ρ
. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΠΎΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΡΠΉ ΡΡΠ΅Ρ Π³ΡΠ°Π½ΠΈΡΠ½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΠΉ ΡΠ»Π΅ΠΊΡΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΡΠΎΡΠΌΠ΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° ΡΠ²ΡΠ·ΠΈ, Π²ΠΊΠ»ΡΡΠ°ΡΡΠ΅ΠΉ ΠΎΠ±ΡΠ΅ΠΌΠ½ΡΡ ΠΈ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΡΡ ΡΠΎΡΡΠ°Π²Π»ΡΡΡΠΈΠ΅. Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π½ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ Π΄Π»Ρ ΡΠ°ΡΡΠ΅ΡΠ° Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΎΠ½Π½ΡΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ Π½ΠΈΠ·ΡΠΈΡ
Π²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π½ΡΡ
ΠΌΠΎΠ΄, ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½ΡΡΡΠΈΡ
ΡΡ Π² ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π°Ρ
ΡΡΠ°ΠΏΠ΅ΡΠΈΠ΅Π²ΠΈΠ΄Π½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ, ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΡ
Π½Π° ΠΏΡΠ°ΠΊΡΠΈΠΊΠ΅. ΠΡΠΎΠ΄Π΅ΠΌΠΎΠ½ΡΡΡΠΈΡΠΎΠ²Π°Π½ΠΎ Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π° Π½Π° Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΎΠ½Π½ΡΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΠΌΠΎΠ΄ Π² Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΎΡ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΡ ΡΡΠΎΡΠΎΠ½, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΎΡ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΡ Π·Π½Π°ΡΠ΅Π½ΠΈΠΉ Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠΎΠ½ΠΈΡΠ°Π΅ΠΌΠΎΡΡΠ΅ΠΉ ΡΠ΅ΡΠ΄ΡΠ΅Π²ΠΈΠ½Ρ ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π° ΠΈ Π΅Π³ΠΎ ΠΎΠ±ΠΎΠ»ΠΎΡΠΊΠΈ. ΠΠΎΠΊΠ°Π·Π°Π½Π° Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡ ΡΡΠ΅ΡΠ° Π²Π»ΠΈΡΠ½ΠΈΡ ΡΠΎΡΠΌΡ ΠΌΠΈΠΊΡΠΎΠ²ΠΎΠ»Π½ΠΎΠ²ΠΎΠ΄Π° Π½Π° Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΎΠ½Π½ΡΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΠΌΠΎΠ΄ Π² ΡΠΈΡΠΎΠΊΠΎΠΌ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ Π·Π½Π°ΡΠ΅Π½ΠΈΠΉ ΡΠ°Π±ΠΎΡΠΈΡ
Π΄Π»ΠΈΠ½ Π²ΠΎΠ»Π½ ΠΈ ΠΏΡΠΈ ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡΡ
Π΄ΠΈΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠ½ΠΈΡΠ°Π΅ΠΌΠΎΡΡΠΈ Π²ΠΎΠ»Π½ΠΎΠ²Π΅Π΄ΡΡΠ΅ΠΉ ΡΡΡΡΠΊΡΡΡΡ
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