共查询到20条相似文献,搜索用时 15 毫秒
1.
The effect of an external magnetic field on the nonlinear interaction of S-polarized electromagnetic radiation incident on a S-polarized surface wave in a plasma layer was studied analytically. We have calculated the amplitudes of generated waves at combination frequencies. The generated waves are of P-polarization and can be either electromagnetic or surface waves, depending on the signal of the value=\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\chi '^2 = \frac{{k'^2 }}{{\varepsilon '}} - \frac{{\omega '^2 }}{{c^2 }} + k'\frac{\partial }{{\partial x}}\frac{{\varepsilon '_2 }}{{\varepsilon '\varepsilon '_1 }}} $\end{document}. 相似文献
2.
H. C. Hsieh 《International Journal of Infrared and Millimeter Waves》1981,2(1):131-147
The expression for free carrier Faraday rotation and for ellipticity , as the function of the applied parallel static electric field
and static magnetic field
for a given value of wave angular frequency and electron concentration N0, are obtained and theoretically analyzed with the aid of one-dimensional linearized wave theory and Kane's non-parabolic isotropic dispersion law. It is shown that the maximum Faraday rotation occurs near the cyclotron resonance condition, which can be expressed as
, where
,
, and
. Here m* and e denote the effective mass and charge of electron, respectively. g is the forbidden bandgap of semiconductor. v0 is the carrier drift velocity, which is a non-linear function of E0 in high field condition. A possibility of a simple way of determining the non-linear v0 vs E0 characteristics of semiconductors by the measurement of Faraday rotation is also discussed. 相似文献
3.
Hua Li Jianping Sang Chang Liu Hongbing Lu Juncheng Cao 《Central European Journal of Physics》2008,6(3):638-642
Single crystalline ZnO film is grown on GaN/sapphire (0001) substrate by molecular beam epitaxy. Ga2O3 is introduced into the ZnO/GaN heterostructure intentionally by oxygen-plasma pre-exposure on the GaN surface prior to ZnO
growth. The crystalline orientation and interfacial microstructure are characterized by X-ray diffraction and transmission
electron microscopy. X-ray diffraction analysis shows strong c-axis preferred orientation of the ZnO film. Cross-sectional
transmission electron microscope images reveal that an additional phase is formed at the interface of ZnO/GaN. Through a comparison
of diffraction patterns, we confirm that the interface layer is monoclinic Ga2O3 and the main epitaxial relationship should be and .
相似文献
4.
R. Orbach 《Hyperfine Interactions》1989,49(1-4):325-333
The excitation dynamics of site diluted magnets can be described at low energies (long length scales) by magnons, and above
a crossover frequency, ωc, (short length scales) by fractons. The density of fracton states is given by
, where
is the fracton dimensionality. Dilution gives rise to a characteristic length ξ∝(p−p
c)ν, wherep
c is the critical concentration for (magnetic) percolation. The crossover frequency ωc is proportional to ξ-1[1+(θ/2)], where θ is the rate at which the diffusion constant decays with distance for diffusion on an equivalent network. A fractal
dimensionD describes the density of magnetic sites on the infinite network, and
. For percolating networks,
for all dimensions ≥2. Neutron scattering structure factor measurements by Uemura and Birgeneau compare well with calculations
using fracton concepts.
Magnons are extended at low energies, while the fracton states are geometrically localized, with a wave function envelope
proportional to exp
. Here,
is the fracton length scale at frequency ω. The exponentd
ϕ lies between 1 andd
min, the chemical length index (of the order of 1.6 in three dimensions). The localization of the magnetic excitations causes
a spread in the NMR relaxation rates. A given nuclear moment will experience only a limited set of fracton excitations, resulting
in an overall non-exponential decay of the NMR relaxation signal. When strong cross-relaxation is present, the relaxation
will be exponential, but the temperature dependence will be strongly altered from the concentrated result. 相似文献
5.
O. V. Kibis 《Russian Physics Journal》1997,40(8):780-783
Taking the inelastic nature of the interaction of electrons with acoustic phonons into account is crucial in crystals having
a conduction band width Δɛ comparable to the maximum acoustic phonon energy
. In view of this, the laws of conservation of energy and wave vector impose stringent constraints on possible electron scattering
processes, and single-phonon scattering becomes impossible for
. The phonon contribution to the resistance may be negligible, therefore, in narrow-band conductors.
Novosibirsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, p. 78–82, August, 1997. 相似文献
6.
7.
The linear and nonlinear optical properties in non-centro-symmetric cubic
semiconductor GaX (X=As, Sb, P) are studied by using the first-principle
full potential linear augmented plane wave (FP-LAPW) and the linear
muffin-tin orbital (LMTO) methods. We present calculations of the
frequency-dependent complex dielectric function
and it zero-frequency limit
. A
simple scissor operator is applied to adjust the band gap from the
local-density calculations to match the experimental value. Calculations are
reported for the frequency-dependent complex second-order non-linear optical
susceptibilities
up to 6 eV and it
zero-frequency limit
. Comparison with available
experimental data shows good agreement. Our calculations show excellent
agreement between the two methods. 相似文献
8.
The product of two real spectral triples
and
, the first of which is necessarily even, was defined by A.Connes as
given by
and, in the even-even case, by
. Generically it is assumed that the real structure
obeys the relations
,
,
, where the
-sign table depends on the dimension n modulo 8 of the spectral triple. If both spectral triples obey Connes'
>-sign table, it is seen that their product, defined in the straightforward way above, does not necessarily obey this
-sign table. In this Letter, we propose an alternative definition of the product real structure such that the
-sign table is also satisfied by the product. 相似文献
9.
Fluctuation spectrum in an exactly solvable model with dissipation: A new model of the Flicker noise
O. Yu. Dinariev 《Russian Physics Journal》1990,33(10):821-826
A system is considered consisting of a harmonic oscillator and a field interacting with it. A quadratic Lagrangian is used, so that the model is exactly solvable. Under some conditions, the model exhibits a dissipative behavior of a selected oscillator. A canonical transformation is found which brings the Hamiltonian to a diagonal form, which is used to compute the quantum correlation and spectral functions of the oscillator fluctuations. It is found that the model allows for a low-frequency spectrum of the form
for the driving force, and
for the oscillator coordinate (Flicker noise).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 13–18, October, 1990. 相似文献
10.
M. L. Khodachenko V. M. Gubchenko H. O. Rucker 《Radiophysics and Quantum Electronics》1998,41(10):813-825
To explain self-consistently some energetic processes, radiation features, and the electromagnetic environment near the Io
satellite moving in the Jovian magnetospheric plasma, as well as a spacecraft body or a plasma probe, we consider, by means
of plasma kinetic theory, the process of electromagnetic interaction between a moving conducting body and the surrounding
hot magnetized plasma described by the tensorε
ij
(ω, k). We study the field structure in terms of the low-frequency, non-propagating, inductive electromagnetic mode, which is usually
ignored. We investigate the plasma dielectric properties for the frequency ranges
and
, showing the importance of the spatial dispersion connected with particle thermal motion for the behavior of inductive electromagnetic
fields. These fields are localized in the vicinity of the moving conducting body and decay in space due to collisionless energy
dissipation, forming some kind of local magnetosphere. Along with the influence of energy losses of the moving conducting
body, inductive fields could be responsible for the appearance near the body of electromagnetic structures where charged particles
will be effectively accelerated. The general analysis developed here is also applicable for the cases of any artificial spacecraft
body or tethered satellite system slowly (V0≪VA, Ve) moving in the magnetized plasma of the ionosphere and in a low earth orbit.
The materials of this paper were reported at the IIIrd International School on Space Plasma Physics.
Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia; Space Research Institute of the
Austrian Academy of Sciences, Graz, Austria. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41,
No. 10, pp. 1209–1225, October 1998. 相似文献
11.
A Dega-Dałkowska 《Pramana》1990,35(4):355-360
The temperature dependence of shear viscosity of the system nitrobenzene-n-heptane has been studied near the critical concentration. The critical exponent of the shear viscosity Φ was calculated from
the empirical formula
and compared with the theoretical and experimental results obtained for other critical systems. The shear viscosity satisfies
scaling law relations similar to those previously established for equilibrium properties. 相似文献
12.
Given n2, we put r=min
. Let be a compact, C
r
-smooth surface in n which contains the origin. Let further
be a family of measurable subsets of such that
as
. We derive an asymptotic expansion for the discrete spectrum of the Schrödinger operator
in L
2(
n
), where is a positive constant, as
. An analogous result is given also for geometrically induced bound states due to a interaction supported by an infinite planar curve. 相似文献
13.
The structures of two phases of the (NH4)3Nb(O2)2F4 crystal, namely, the parent cubic phase and the most distorted low-temperature phase, have been determined from data of an
X-ray diffraction experiment performed for a powder sample. The profile and structural parameters have been refined according
to the procedure implemented in the DDM program. The results obtained have been discussed with invoking the group-theoretical
analysis of the complete order parameter condensate, which takes into account the critical and noncritical atomic displacements
and allows the interpretation of the obtained experimental data. It has been found that the most probable sequence of structural
transformations occurring in the crystal can be schematically represented in the following form:
_boxclose_boxclose_boxclose_boxclose_boxclose_boxclose_boxclose_boxclose] _5^ + (11 - 7)C2/mP2_1 /m | #xA; P2_1 /n. | #xA; |
#xA;\begin{gathered}
Fm\bar 3m\xrightarrow[{(\eta 1,\eta 1,\eta )}]{{\Gamma _5^ + (11 - 7)}}C2/m\xrightarrow[{(\eta 1,\eta 1,\eta )(0,0,0,0,0,\xi ,0 - \xi ,0,0,0,0)}]{{\Gamma _5^ + (11 - 7) \otimes \Sigma _2 (4 - 2)}}P2_1 /m \hfill \\
\xrightarrow[{(\eta 1,\eta 1,\eta )(0,0,0,0,0,\xi ,0 - \xi ,0,0,0,0)(0,0,0,0,0,\varepsilon ,0,\varepsilon ,0,0,0,0)}]{{\Gamma _5^ + (11 - 7) \otimes \Sigma _2 (4 - 2) \otimes \Sigma _3 (4 - 3)}}P2_1 /n. \hfill \\
\end{gathered}
相似文献
14.
The paper investigates the modification of the quasiparticle excitation spectrum of type‐II superconductors caused by the
formation of a flux‐line lattice and its effects on the tunnelling rate of light positively charged interstitial particles.
It is shown that near the upper critical field Bc2 the BCS–Gorkov equations predict for the spectral density J(\omega) (giving the probability of an energy exchange \hbar\omega
between particle and the electron system) “superohmic” behaviour \propto \omega3/2 at low frequencies with a prefactor that depends on the position of the tunnelling centre relative to the flux‐line lattice
and on the angle between jump vector and the flux‐lines. As in normal‐conducting metals, at higher frequencies J(\omega)=2Kel\omega, is predicted. At low temperatures T the superohmic J(\omega) leads to hopping rates \nu \propto T-2. At higher temperatures a crossover to the Kondo law (
) is expected.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
V. I. Al’shits N. N. Bekkauer A. E. Smirnov A. A. Urusovskaya 《Journal of Experimental and Theoretical Physics》1999,88(3):523-526
A constant magnetic field is found to have a substantial effect on the macroplasticity of NaCl crystals when they are being
actively strained at a constant rate
during magnetic treatment. We have measured the dependence of the yield point σ
y
on the magnetic induction B=0–0.48 T and the strain rate
. It is shown that this magnetic effect has a threshold character and is observed only for B>B
c
, where B
c
grows with increasing
as
. The lower the strain rate
, the larger the relative decrease in the yield point σ
y
(B)/σ
y
(0) at fixed field B>B
c
. At small enough strain rates
the threshold field B
c
ceases to depend on
and goes constant. A theoretical model is proposed which is in good agreement with the observed regularities. The model is
based on the competition between thermally activated and magnetically stimulated depinning of dislocations from paramagnetic
impurity centers.
Zh. éksp. Teor. Fiz. 115, 951–958 (March 1999) 相似文献
16.
In this paper, we study the global regularity for the Navier-Stokes-Maxwell system with fractional diffusion. Existence and uniqueness of global strong solution are proved for \(\alpha \geqslant \frac {3}{2}\). When 0 < α < 1, global existence is obtained provided that the initial data \(\|u_{0}\|_{H^{\frac {5}{2}-2\alpha }}+\|E_{0}\|_{H^{\frac {5}{2}-2\alpha }}+\|B_{0}\|_{H^{\frac {5}{2}-2\alpha }}\) is sufficiently small. Moreover, when \(1<\alpha <\frac {3}{2}\), global existence is obtained if for any ε >?0, the initial data \(\|u_{0}\|_{H^{\frac {3}{2}-\alpha +\varepsilon }}+\|E_{0}\|_{H^{\frac {3}{2}-\alpha +\varepsilon }}+\|B_{0}\|_{H^{\frac {3}{2}-\alpha +\varepsilon }}\) is small enough. 相似文献
17.
Ashok Kumar 《Applied physics. B, Lasers and optics》2013,110(1):117-121
Terahertz radiation generation by second-order nonlinear mixing of laser $ (\omega_{1} ,\,\vec{k}_{1} ) $ and its frequency shifted second harmonic $ \omega_{2} = 2\omega_{1} - \omega ,\,\,\vec{k}_{2} \, $ $ (\omega \ll \omega_{1} ) $ in a plasma, in the presence of an obliquely inclined density ripple of wave number $ \vec{q} $ , are investigated. The lasers exert ponderomotive force on electrons and drive density perturbations at $ (2\omega_{1} ,\,2\vec{k}_{1} - \vec{q}) $ and $ (\omega_{1} - \omega_{2} ,\,\vec{k}_{1} - \vec{k}_{2} - \vec{q}) $ . These perturbations beat with the electron oscillatory velocities due to the lasers to produce a nonlinear current at $ \omega ,\,\vec{k} = 2\vec{k}_{1} - \vec{k}_{2} - \vec{q} $ , resonantly driving the terahertz radiation when $ \vec{q} $ satisfies the phase matching condition. The radiated THz intensity depends on the relative polarization of the lasers and scales as the square of intensity of the fundamental laser and linearly with the square root of the intensity of the second harmonic. The THz emission is maximized when the polarization of the lasers is aligned. These results are consistent with the recent experimental results. 相似文献
18.
M. Paulus P. Degen S. Schmacke M. Maas R. Kahner B. Struth M. Tolan H. Rehage 《The European physical journal. Special topics》2009,167(1):133-136
The adsorption of (maghemite) nanoparticles at the aqueous solution/gas interface was investigated by x-ray reflectivity. Two different concentrations
(0.07 g/L and 0.7 g/L) were probed. The x-ray reflectivities indicate the adsorption of nanoparticles at the liquid surface
for the highly concentrated solution, while no nanoparticle adsorption could be detected at the surface of the low concentrated
solution within several hours. The vertical electron density profile of the high concentration solution/gas interface indicates
the formation of a low ordered monolayer of nanoparticles occupying only 6% of the interfacial region. 相似文献
19.
Exact solutions of the D-dimensional Schrödinger equation for a ring-shaped pseudoharmonic potential
A new non-central potential, consisting of a pseudoharmonic potential plus another recently proposed ring-shaped potential, is solved. It has the form $ V(r,\theta ) = \tfrac{1} {8}\kappa r_e^2 \left( {\tfrac{r} {{r_e }} - \tfrac{{r_e }} {r}} \right)^2 + \tfrac{{\beta cos^2 \theta }} {{r^2 sin^2 \theta }}
20.
We use the recursion method to calculate the vibrational density of states
of site percolation clusters slightly above the percolation threshold. It is found that
is proportional to at long wavelengths. At shorter length scales,
is proportional to
, with the fraction dimension
. The cross-over from phonon to fraction regime is characterized by a rapid rise in
in agreement with effective medium calculations. 相似文献
|