2,662 research outputs found
On the internal modes in sine-Gordon chain
We address the issue of internal modes of a kink of a discrete sine-Gordon
equation. The main point of the present study is to elucidate how the
antisymmetric internal mode frequency dependence enters the quasicontinuum
spectrum of nonlocalized waves. We analyze the internal frequency dependencies
as functions of both the number of cites and discreteness parameter and explain
the origin of spectrum peculiarity which arises after the frequency dependence
of antisymmetric mode returns back to the continuous spectrum at some nonzero
value of the intersite coupling.Comment: 5 pages, 3 figure
Radiation Pressure Quantization
Kepler's observation of comets tails initiated the research on the radiation
pressure of celestial objects and 250 years later they found new incarnation
after the Maxwell's equations were formulated to describe a plethora of
light-matter coupling phenomena. Further, quantum mechanics gave birth to the
photon drag effect. Here, we predict a novel universal phenomenon which can be
referred to as quantization of the radiation pressure. We develop a microscopic
theory of this effect which can be applied to a general system containing
Bose-Einstein-condensed particles, which possess an internal structure of
quantum states. By analyzing the response of the system to an external
electromagnetic field we find that such drag results in a flux of particles
constituting both the condensate and the excited states. We show that in the
presence of the condensed phase, the response of the system becomes quantized
which manifests itself in a step-like behavior of the particle flux as a
function of electromagnetic field frequency with the elementary quantum
determined by the internal energy structure of the particles.Comment: Manuscript: 4 pages, 3 figure
First-principles calculation of spin-orbit torque in a Co/Pt bilayer
The angular dependence of spin-orbit torque in a disordered Co/Pt bilayer is
calculated using a first-principles non-equilibrium Green's function formalism
with an explicit supercell averaging over Anderson disorder. In addition to the
usual dampinglike and fieldlike terms, the odd torque contains a sizeable
planar Hall-like term whose contribution to
current-induced damping is consistent with experimental observations. The
dampinglike and planar Hall-like torquances depend weakly on disorder strength,
while the fieldlike torquance declines with increasing disorder. The torques
that contribute to damping are almost entirely due to spin-orbit coupling on
the Pt atoms, but the fieldlike torque does not require it.Comment: 11 pages, 5 figure
Theory of spin loss at metallic interfaces
Interfacial spin-flip scattering plays an important role in magnetoelectronic
devices. Spin loss at metallic interfaces is usually quantified by matching the
magnetoresistance data for multilayers to the Valet-Fert model, while treating
each interface as a fictitious bulk layer whose thickness is times the
spin-diffusion length. By employing the properly generalized circuit theory and
the scattering matrix approaches, we derive the relation of the parameter
to the spin-flip transmission and reflection probabilities at an
individual interface. It is found that is proportional to the square
root of the probability of spin-flip scattering. We calculate the spin-flip
transmission probability for flat and rough Cu/Pd interfaces using the
Landauer-B\"uttiker method based on the first-principles electronic structure
and find in reasonable agreement with experiment.Comment: 5 pages + supplementary material, 3 figures, version accepted in
Phys. Rev. Let
Planning the forest transport systems based on the principles of sustainable development of territories
The article identifies a new method of dynamic modeling in the design of the transport system in the forest fund (TSFF), which is based on economic and mathematical modeling and fuzzy logic tools. The combination of the indicated methods is designed to reduce the disadvantages of their use and increase the benefits. The article substantiates the choice of assessing the forecast level of the impact of risks on the activities of forestry enterprises (the method of expert assessments), using the methodological tools of fuzzy logic. The indicated method makes it possible to take into account a large variety of risk factors of the internal and external environment. At the same time, methodological aspects of fuzzy logic make it possible to formulate a quantitative assessment of qualitative indicators. The article substantiates the choice of tools for economic and mathematical modeling in order to state the design problem of the planned TSFF. Since the indicated method enables the formalization of the functioning of the timber transport system in the given conditions. The article presents a developed model that correctly takes into account the influence of risk factors when planning a TSFF, through the combination of fuzzy logic methods and economic and mathematical modeling. The advantages of the developed model include: considering the multivariance of material flows, vehicles, points of overload, etc.; automated processing of input parameters and effective data; using the model for forecasting, i.e. the possibility of deriving a fuzzy estimate of the efficiency of the timber transport system by identifying cause-effect relationships between the modeling object and the influence of risk factors on its functioning. © 2019 IOP Publishing Ltd
Rashba plasmon polaritons in semiconductor heterostructures
We propose a concept of surface plasmon-polariton amplification in the
structure comprising interface between dielectric, metal and asymmetric quantum
well. Due to the Rashba spin-orbit interaction, mimina of dispersion relation
for electrons in conduction band are shifted with respect to the maximum of
dispersion dependence for holes in -point. When energy and momentum
intervals between extrema in dispersion relations of electrons and holes match
dispersion relation of plasmons, indirect radiative transition can amplify the
plasmons; excitation of leaky modes is forbidden due to the selection rules.
Efficiency of the indirect radiative transition is calculated and design of the
structure is analysed.Comment: Published (4 pages + 3 figures), 2nd proof versio
- …