Generation of Nanometer Wavelength Acoustic Waves

The possibility of acoustic wave generation of nanometer range in plates is shown. The experimental results that show the possible reconfiguring of the generator frequency in YFeO3 with a constant magnetic field are given

Method for the Determination of Magnetoelastic and Elastic Constants of Weak Ferromagnets

Excitation of flexible vibrations in weak ferromagnets plaes in an external magnetic field is experimentally investigated. It is proposed to use dependence of resonant frequencies on a magnetic field for tunable source of flexural vibrations. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3367

Interaction of Lamb Waves with Domain Walls in an Iron Borate Plate

This work presents the calculation results of the Lamb wave spectra in a plate of iron borate. Experimental data on how flexural vibrations in a borate plate influence its domain structure are provided

Dynamics of Domain Walls in Iron Borate and Yttrium Orthoferrite in Alternating and Constant Magnetic Fields

The velocity of domain wall in iron borate and yttrium orthoferrite as a function of a driving alternat-ing magnetic field with a constant magnetic field present is experimentally investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3635

Generation of Nanometer Wavelength Acoustic Waves

The possibility of acoustic wave generation of nanometer range in plates is shown. The experimental results that show the possible reconfiguring of the generator frequency in YFeO3 with a constant magnetic field are given

Weakly-Bound Three-Body Systems with No Bound Subsystems

We investigate the domain of coupling constants which achieve binding for a 3-body system, while none of the 2-body subsystems is bound. We derive some general properties of the shape of the domain, and rigorous upper bounds on its size, using a Hall--Post decomposition of the Hamiltonian. Numerical illustrations are provided in the case of a Yukawa potential, using a simple variational method.Comment: gzipped ps with 11 figures included. To appear in Phys. Rev.

The “Horizon-T” Experiment: Extensive Air Showers Detection

Horizon - T is a n innovative detector system constructed to study Extensive Air Showers (EAS) in the energy range above 10 16 eV coming from a wide range of zenith angles (0 o - 85 o ). The system is located at Tien Shan high - altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. It consists of eight charged particle detection points separated by the distance up to one kilometer as well as optical detector subsystem to view the Vavilov - Cherenkov light from the EAS. The time resolution of charged particles and Vavilov - Cherenkov light photons passage of the detector system is a few ns. This level of resolution allows conducting research of atmos pheric development of individual EAS

The helium trimer with soft-core potentials

The helium trimer is studied using two- and three-body soft-core potentials. Realistic helium-helium potentials present an extremely strong short-range repulsion and support a single, very shallow, bound state. The description of systems with more than two helium atoms is difficult due to the very large cancellation between kinetic and potential energy. We analyze the possibility of describing the three helium system in the ultracold regime using a gaussian representation of a widely used realistic potential, the LM2M2 interaction. However, in order to describe correctly the trimer ground state a three-body force has to be added to the gaussian interaction. With this potential model the two bound states of the trimer and the low energy scattering helium-dimer phase shifts obtained with the LM2M2 potential are well reproduced.Comment: 15 pages, 3 figures, submitted to Few-Body System

Impact of the carrier relaxation paths on two-state operation in quantum dot lasers

We study InGaAs QD laser operating simultaneously at ground (GS) and excited (ES) states under 30ns pulsed-pumping and distinguish three regimes of operation depending on the pump current and the carrier relaxation pathways. An increased current leads to an increase in ES intensity and to a decrease in GS intensity (or saturation) for low pump range, as typical for the cascade-like pathway. Both the GS and ES intensities are steadily increased for high current ranges, which prove the dominance of the direct capture pathway. The relaxation oscillations are not pronounced for these ranges. For the mediate currents, the interplay between the both pathways leads to the damped large amplitude relaxation oscillations with significant deviation of the relaxation oscillation frequency from the initial value during the pulse

The effect of slow passage in the pulse-pumped quantum dot laser

In recent years, quantum-dot (QD) semiconductor lasers attract significant interest in many practical applications due to their advantages such as high-power pulse generation because to the high gain efficiency. In this work, the pulse shape of an electrically pumped QD-laser under high current is analyzed. We find that the slow rise time of the pulsed pump may significantly affect the high intensity output pulse. It results in sharp power dropouts and deformation of the pulse profile. We address the effect to dynamical change of the phase-amplitude coupling in the proximity of the excited state (ES) threshold. Under 30ns pulse pumping, the output pulse shape strongly depends on pumping amplitude. At lower currents, which correspond to lasing in the ground state (GS), the pulse shape mimics that of the pump pulse. However, at higher currents the pulse shape becomes progressively unstable. The instability is greatest when in proximity to the secondary threshold which corresponds to the beginning of the ES lasing. After the slow rise stage, the output power sharply drops out. It is followed by a long-time power-off stage and large-scale amplitude fluctuations. We explain these observations by the dynamical change of the alpha-factor in the QD-laser and reveal the role of the slowly rising pumping processes in the pulse shaping and power dropouts at higher currents. The modeling is in very good agreement with the experimental observations