A5009324775- Magnetic properties of thin films
- Magneto-Optical Properties and Applications
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Magnetic Properties and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum optics and atomic interactions
- Mechanical and Optical Resonators
- Magnetic Properties and Synthesis of Ferrites
- Strong Light-Matter Interactions
- Electromagnetic Effects on Materials
- Nonlinear Dynamics and Pattern Formation
- Acoustic Wave Resonator Technologies
- Quantum, superfluid, helium dynamics
- Geophysics and Sensor Technology
- Photonic and Optical Devices
- Gyrotron and Vacuum Electronics Research
- Theoretical and Computational Physics
- Photonic Crystals and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Nonlinear Photonic Systems
- ZnO doping and properties
- Advanced Frequency and Time Standards
- Atomic and Subatomic Physics Research
- Metamaterials and Metasurfaces Applications
Taras Shevchenko National University of Kyiv
2012-2022
Simon Fraser University
2013
Northrop Grumman (United States)
2013
Oakland University
2013
Singulus (Germany)
2013
International Council on Mining and Metals
2013
University of Kaiserslautern
2009-2013
Institute of Electrodynamics
1997
Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in GHz-to-THz frequency range, utilization nonlinear nonreciprocal phenomena, compatibility with CMOS are just a few many advantages offered by magnons. Although magnonics is still primarily positioned academic domain, scientific technological challenges field being extensively investigated, proof-of-concept prototypes have already been realized...
We present spatially resolved measurements of the magnon temperature in a magnetic insulator subject to thermal gradient. Our data reveal an unexpectedly close correspondence between spatial dependencies exchange and phonon temperatures. These results indicate that if--as is currently thought--the transverse spin Seebeck effect caused by difference baths, it must be case spectrally nonuniform driven sparsely populated dipolar region spectrum.
The room-temperature dynamics of a magnon gas driven by short microwave pumping pulses is studied. An overpopulation the lowest energy level system following observed. Using sensitivity Brillouin light scattering technique to coherence degree magnons we demonstrate spontaneous emergence at level, if their density exceeds critical value. This finding clear proof quantum nature observed phenomenon and direct evidence Bose-Einstein condensation room temperature.
A general theory of collective spin-wave excitations in a two-dimensional array magnetic nanodots coupled by magnetodipolar interaction is developed. The allows one to analytically calculate spectra, damping rates, excitation efficiencies, and other characteristics spin waves both periodic aperiodic ground states an array. It demonstrated that all the properties existing any spatially state (e.g., ferromagnetic or chessboard antiferromagnetic) are determined same state-independent array's...
An ensemble of magnons, quanta spin waves, can be prepared as a Bose gas weakly interacting quasiparticles. Furthermore, the thermalization overpopulated magnon through magnon-magnon scattering processes, which conserve number particles, lead to formation Bose-Einstein condensate at bottom spin-wave spectrum. However, magnon-phonon significantly modify this scenario and new quasiparticles are formed---magnetoelastic bosons. Our observations parametrically populated in single-crystal film...
The thermalization of parametrically pumped magnons caused by nonlinear multimagnon scattering processes and leading to the magnon Bose-Einstein condensation is investigated experimentally with high temporal resolution. threshold pumping power necessary for determined. For powers above this time has been found decrease rapidly reaching value down 50 ns, which much smaller than lifetime.
Using a novel technique providing simultaneous resolution with respect to the wave vector and frequency of magnons, we observed formation Bose-Einstein condensate documented by narrowing magnon distribution in phase space. Based on measured width determined effective correlation length condensate, which appears be anisotropic, reflecting anisotropy dispersion spectrum.
It is demonstrated that collective spin waves (SWs) propagating in complex periodic arrays of dipolarly coupled magnetic nanopillars existing a saturated (single-domain) ground state zero bias field could be nonreciprocal. To guarantee the SW nonreciprocity, two conditions should fulfilled: (i) existence nonzero out-of-plane component pillars' static magnetization and (ii) periodicity array's with at least elements per primitive cell, if are different, three identical.
It was shown by micromagnetic simulation that a current-driven in-plane magnetized magnetic nanocontact, besides quasilinear propagating (``Slonczewski'') spin-wave mode, can also support nonlinear self-localized ``bullet'' mode exists in much wider range of bias currents. The frequency the bullet lies below spectrum linear spin waves, which makes this evanescent and determines its spatial localization. threshold current for excitation is substantially lower than but finite-amplitude initial...
We demonstrate that a microwave signal carried by packet of dipolar spin waves propagating in tangentially magnetized magnetic film can be stored the form standing dipole-exchange spin-wave modes and recovered means double-frequency parametric pumping mechanism. This mechanism is based on amplification (thickness) external pumping. The time recovery, duration, power pulse are controlled signal.
The damping of spin waves parametrically excited in the magnetic insulator Yttrium Iron Garnet (YIG) is controlled by a dc current passed through an adjacent normal-metal film. experiment performed on macroscopically sized YIG(100 nm)/Pt(10 nm) bilayer 4 × 2 mm2 lateral dimensions. spin-wave relaxation frequency determined via threshold parametric instability measured Brillouin light scattering spectroscopy. application to Pt film leads formation spin-polarized electron normal plane due Hall...
Parametric interaction of a propagating dipolar spin wave envelope soliton (carrier frequency ${\ensuremath{\omega}}_{s}$, duration ${\ensuremath{\tau}}_{s}$, and velocity ${\ensuremath{\nu}}_{s}$) with electromagnetic pumping (frequency ${\ensuremath{\omega}}_{p}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2{\ensuremath{\omega}}_{s}$), localized in spatial region width L, has been observed magnetic films for the first time. The necessary bandwidth was guaranteed by choosing...
It is shown that in a spin-torque microwave oscillator based on magnetic nanocontact, the nature of spin wave mode generated at threshold critically depends angle between external bias field and plane free layer. When rotating from normal to in-plane orientation, an abrupt transition propagating cylindrical with frequency higher than linear ferromagnetic resonance (FMR) self-localized standing nonlinear ``bullet'' lower FMR takes place certain intermediate...
Bose-Einstein condensation in a gas of magnons pumped by an incoherent pumping source is experimentally studied at room temperature. We demonstrate that the can be achieved bosons under conditions pumping. The critical transition point shown to almost independent frequency spectrum and solely determined density magnons. electromagnetic power radiated magnon condensate found scale quadratically with power. obtained results are good agreement theory quasiequilibrium
We show numerically that a ground state (ferromagnetic or chessboard antiferromagnetic) and microwave absorption frequency of dipolarly coupled two-dimensional array axially magnetized magnetic nano-dots can be switched by application bias field pulses (duration 30–70 ns). Switching to the ferromagnetic achieved applying rectangular pulse along dot axis while switching antiferromagnetic requires oriented in plane having sufficiently long trailing edge (tail). Our results prove arrays used as...
We analyze performance of a resonance-type spin-torque microwave detector (STMD) in the presence noise and reveal two distinct regimes STMD operation. In high-frequency regime, minimum detectable power Pmin is limited by low-frequency Johnson-Nyquist signal-to-noise ratio (SNR) proportional to input PRF. magnetic noise, SNR The developed formalism can be used for optimization practical noise-handling parameters STMD.
Thermalization of a parametrically driven magnon gas leading to the formation Bose-Einstein condensate at bottom spin-wave spectrum was studied by time- and wavevector-resolved Brillouin light scattering spectroscopy. It has been found that condensation is preceded conversion initially pumped magnons into second group frequency degenerated magnons, which appear due stimulated initial short-wavelength spectral region. In contrast first group, wavevectors are orthogonal lowest energy states,...
Nano-structuring can significantly modify the properties of materials. We demonstrate that size-dependent modification spin-wave spectra in magnetic nano-particles affect not only linear, but also nonlinear response. The discretization spectrum removes frequency degeneracy between main excitation mode a nano-particle and higher modes, having lowest damping reduces strength multi-magnon relaxation processes. This reduction magnon-magnon for leads to dramatic increase its lifetime amplitude,...
Nonlinear interactions of dipolar and dipole-exchange spin waves with microwave magnetic field parametric electromagnetic pumping were studied experimentally in thin permalloy (Py) films. It was demonstrated that Py films leads to efficient amplification the ``trace'' quasistanding created due two-magnon scattering by input signal pulse long-wavelength and, then, suppression amplified excitation short-wavelength exchange-dominated waves. was, also, shown nonlinear can be used for development...