共查询到20条相似文献,搜索用时 31 毫秒
1.
Longhi S 《Optics letters》2006,31(12):1857-1859
The possibility of controlling discrete diffraction and refraction in a multiband waveguide array by periodic waveguide bending is theoretically demonstrated. Resonance effects, leading to the enhancement or inhibition of discrete diffraction, are found and related to the quantum analog of field-induced n-photon resonances in semiconductor superlattices. A very distinct behavior for light refraction is found for odd or even resonances. In particular, for even resonances, the two-band behavior of the straight binary array is quenched, resulting in the inhibition of double refraction. 相似文献
2.
K. V. Shandarova V. M. Shandarov E. V. Smirnov D. Kip Ch. Rüter Ya. Tan F. Chen 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(12):1617-1619
Some features of discrete diffraction of light, which manifest themselves in the possibility of its linear and nonlinear localization in one or several waveguide elements, in photorefractive photonic superlattices optically induced in lithium niobate crystals, and in planar optical waveguides based on this material, have been experimentally investigated. 相似文献
3.
The dependence of Co nanoparticle sizes on the ratio of surfactants and the influence of different crystal sizes on magnetic properties 总被引:1,自引:0,他引:1
Y.K. Su C.M. Shen T.Z. Yang H.T. Yang H.J. Gao H.L. Li 《Applied Physics A: Materials Science & Processing》2005,81(3):569-572
Monodisperse cobalt nanoparticles were synthesized by high-temperature reduction of solution-phase cobalt chloride in the presence of a pair of surfactants, oleic acid and triphenylphosphine. Highly ordered two-dimensional superlattices of passivated cobalt nanoparticles were formed by a self-assembly technique. Analysis by X-ray diffraction, UV-vis absorption spectroscopy and transmission electron microscopy demonstrated that the size of the cobalt nanocrystals could be tuned by tailoring the concentration ratio of the two surfactants. In addition, the influence of different crystal sizes on magnetic properties of Co nanocrystals was also investigated. PACS 75.60.Nt; 75.50.Tt 相似文献
4.
The formation and propagation of dipole domains in superlattices are studied both by the modified discrete drift model and by the nonlinear schroedinger equation,the spatiotemporal distribution of the electric field and electron density are presented.The numerical results are compared with the soliton solutions of the nonlinear Schroedinger equation and analysed.It is shown that the numerical solutions agree with the soliton solutions of the nonlinear Schroedinger equation.The dipole electric-field domains in semiconductor superlattices have the properties of solitons. 相似文献
5.
Specific features of magnetic properties of three-component magnetic superlattices based on Fe/Co/Mo
S. D. Antipov G. E. Goryunov A. P. Krasheninnikov V. A. Senina G. V. Smirnitskaya P. N. Stetsenko 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1613-1614
Synthesis of three-component magnetic superlattices based on the Fe/Co/Mo system by cathode sputtering in an electron-oscillating discharge and their complex investigations have been performed for the first time. The fields have been investigated by X-ray diffraction, vibrational magnetometry, and Mössbauer spectroscopy with the use of completely computerized systems. Oscillations of the main magnetic parameters with a change in the Mo thickness and giant spontaneous magnetization have been found. The properties of three-component superlattices are compared with those of the analogous system based on Fe/Mo. 相似文献
6.
A short account of a new unified interface response theory of composite systems is given. This theory applies as well to discrete as to continuous d-dimensional spaces and enables one to calculate the response function for any composite system from a new simple and general equation. With the help of this response function all the properties associated to a given operator and a composite system can be obtained. A short review of a few physical properties obtained with the help of response functions will be given for vibrational, electronic, magnetic, electromagnetic problems associated with surfaces, interfaces, adsorbates, superlattices,… As an illustration, it will be shown how the interface response theory enables one to solve the Schrödinger equation for free electrons in any composite material, and in particular superlattices. 相似文献
7.
G. B. Galiev E. A. Klimov R. M. Imamov G. V. Ganin S. S. Pushkarev P. P. Maltsev O. M. Zhigalina A. S. Orekhov A. L. Vasil’ev M. Yu. Presniakov I. N. Trunkin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2016,10(3):495-509
InAlAs/InGaAs/InAlAs nanoheterostructures with different structures of metamorphic buffer layer and quantum well, which were grown by means of molecular-beam epitaxy on GaAs and InP substrates, are investigated. The laboratory technology of the growth of the given nanoheterostructures with predicted properties is perfected. The potential of an approach based on the comprehensive analysis of experimental data obtained via different techniques, namely, X-ray diffractometry, electron diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and atomic-force microscopy is studied. The metamorphic buffer layer design is improved on the basis of the results of the performed investigations. A method whereby balanced-mismatched superlattices are introduced directly inside the metamorphic buffer layer is proposed. It is established that the technological parameters of the growth of nanoheterostructures affect their structural perfection and electrophysical properties. 相似文献
8.
Short period InAs(4ML)/GaSb(SML) superlattices (SLs) with InSb- and mixed-like (or Ga1-xInxAs1-ySby- like) interfaces (IFs) are grown by molecular-beam epitaxy (MBE) on (001) GaSh substrates at optimized growth temperature. Raman scattering reveals that two kinds of IFs can be formed by controlling shutter sequences. X-ray diffraction (XRD) and atomic force microscopy (AFM) demonstrate that SLs with mixed-like IFs are more sensitive to growth temperature than that with InSb-like IFs. The photoluminescence (PL) spectra of SLs with mixed-like IFs show a stronger intensity and narrower line width than with InSb-like IFs. It is concluded that InAs/GaSb SLs with mixed-like IFs have better crystalline and optical properties. 相似文献
9.
O. V. Borovkova V. E. Lobanov A. K. Sukhorukova D. A. Chuprakov A. P. Sukhorukov 《Moscow University Physics Bulletin》2008,63(6):430-432
The features of anisotropic discrete diffraction in a cascade-induced lattice formed by two crossed pump waves in a quadratically nonlinear medium have been studied. The transition from the diffraction of a signal beam in free space to discrete diffraction with the further capture in a waveguide in a defocusing lattice by the increasing of the pump wave intensity has been traced. 相似文献
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在Si(100)衬底上用分子束外延在不同的温度下生长了不同组份的GexSi1-x/Si应变层超晶格。用反射式高能电子衍射、X射线双晶衍射、卢瑟福背散射、透射电子显微镜以及Raman。散射等测试方法研究了GexSi1-x/Si超晶格的生长及其结构特性。结果表明,对不同合金组份的超晶格,其最佳生长温度不同。x值小,生长温度高;反之,则要求生长温度低。对于x为0.1—0.6,在400—600℃的生长温度范围能够长成界面平整、
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12.
O. V. Borovkova V. E. Lobanov A. K. Sukhorukova A. P. Sukhorukov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(5):718-720
Regularities of anisotropic discrete diffraction in a cascade-induced lattice formed by two crossed pump waves in a quadratically nonlinear medium have been studied. The transition from diffraction of a signal beam in free space to discrete diffraction with further capture into a waveguide in a defocusing lattice with an increase in the pump wave intensity has been traced. Diffraction-free propagation of a tilted beam is described. 相似文献
13.
The properties of [Pb(Zr(1-x(1))Ti(x(1)))O(3)](n)/[Pb(Zr(1-x(2))Ti(x(2)))O(3)](n) superlattices, with a 2n period, are simulated using an ab initio based approach. The x(1) and x(2) compositions are chosen to be located across the morphotropic phase boundary of the corresponding disordered alloys, while the (x(1)+x(2))/2 average composition lies inside this boundary. These superlattices exhibit an unusual thermodynamic phase transition sequence, including a triclinic ground state. They also have the kind of peculiar free-energy landscape yielding nonergodicity. The effects responsible for these anomalies are discussed. 相似文献
14.
《Superlattices and Microstructures》1998,24(3):239-247
The quantitative characterization of the interface roughness of Fe/Cr superlattices is necessary for the understanding of the transport properties of such structures. This must include both vertical and lateral roughness components. The information can be obtained by specular and off-specular X-ray diffraction and conversion electron Mößbauer spectroscopy. We show how models describing specular and diffuse X-ray diffraction can be applied to extract quantitative data. The robustness of such data can be further enhanced using anomalous scattering, leading to an enhanced material contrast for Fe/Cr. Similarity and complementarity of the X-ray diffraction results with the Mößbauer data are discussed. 相似文献
15.
《Superlattices and Microstructures》1998,23(1):41-47
Neutron diffraction experiments on short-period EuTe/PbTe superlattices with a [111] growth axis reveal distinct magnetic correlations between the EuTe layers across up to 55 Â of non-magnetic PbTe spacers, even though EuTe is antiferromagnetic and there are not enough carriers to support RKKY interactions. With increasing in-plane external magnetic field we observe a decrease of the antiferromagnetic interlayer interactions. This decrease depends very strongly on whether the superlattices are cooled down through the Néel point in zero or non-zero field. 相似文献
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通过化学气相沉积法在一种典型的高指数面铜(410)-氧上制备出了一维石墨烯超晶格,并利用拉曼光谱(Raman)、低能电子衍射(LEED)、扫描隧道显微术(STM)等方法研究了氢原子在该超晶格上的吸附.实验结果揭示了由于超晶格的调制作用所引起的无缺陷石墨烯区域的选择性吸附,氢原子优先吸附在石墨烯超晶格一维周期中的相同部位.这一发现为进一步通过一维超晶格调控石墨烯的性质提供了更多可能.在石墨烯上的吸附氢原子除了单个或成对存在之外,实验还首次观察到一种新的三氢原子位型. 相似文献
18.
Electronic band gap and transport in graphene superlattice with a Gaussian profile potential voltage 下载免费PDF全文
We study the electronic properties for the graphene-based one-dimensional superlattices, whose potential voltages vary according to the envelope of a Gaussian function. It is found that an unusual Dirac point exists and its location is exactly associated with a zero-averaged wave number (zero-re) gap. This zero-k gap is less sensitive to incident angle and lattice constants, properties opposing those of Bragg gap. The defect mode appearing inside the zero-l gap has an effect on transmission, conductance, and shot noise, which will be useful for further investigation. 相似文献
19.
L. A. Chernozatonskiĭ P. B. Sorokin E. É. Belova J. Brüning A. S. Fedorov 《JETP Letters》2007,85(1):77-81
The structures and electron properties of new superlattices formed on graphene by adsorbed hydrogen molecules are theoretically described. It has been shown that superlattices of the (n, 0) zigzag type with linearly arranged pairs of H atoms have band structures similar to the spectra of (n, 0) carbon nanotubes. At the same time, superlattices of the (n, n) type with a “staircase” of adsorbed pairs of H atoms are substantially metallic with a high density of electronic states at the Fermi level and this property distinguishes their spectra from the spectra of the corresponding (n, n) nanotubes. The features of the spectra have the Van Hove form, which is characteristic of each individual superlattice. The possibility of using such planar structures with nanometer thickness is discussed. 相似文献
20.
The diffraction characteristics of a dual-periodicity superlattice—a diffraction grating whose unit cell contains two different regions, one homogeneous and the other periodically nonhomogeneous—were numerically simulated. After choosing the second region to have sinusoidally varying permittivity, the widely used rigorous coupled-wave approach was applied to compute the reflection and transmission efficiency spectrums. An extensive parametric study revealed that the dual-periodicity superlattice exhibits anomalies in the long-wavelength regime which can be considered to be resonance anomalies (RAs), which are distinct from the Rayleigh–Wood anomalies. Also, double-periodicity superlattices exhibit RAs at higher wavelengths than single-periodicity superlattices. 相似文献