共查询到20条相似文献,搜索用时 15 毫秒
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A piezoelectric-piezomagnetic superlattice (PPS) is proposed to present the magneto-electric (ME) coupling wherein electric polarization induces magnetization or vice versa through the layer's coherent strain. We reveal that in PPS, the interaction of electromagnetic waves with the correspondent alternative piezoelectric and piezomagnetic superlattices through their vibrations excites the piezoelectric and the piezomagnetic phonon polaritons simultaneously. The polaritons couple with each other to give rise to a stop band, in which double negative permittivity and permeability can be realized, however negative refraction could not occur. The coupling also results in the huge dynamic ME effect which attributes to the large ME voltage coefficient in a BaTiO3-CoFe2O4 superlattice as large as 14.9 V cm−1 Oe−1. 相似文献
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Electro-magneto-acoustic SH waves propagating oblique to the periodic layered piezoelectric structures are studied under the coupling of the acoustic wave and the electromagnetic wave. Band structures of the so-called piezoelectric superlattice and phononic/photonic crystal are given both at acoustic frequencies and at optical frequencies. For the periodic layered piezoelectric structures, phonon-polaritons (the coupling modes of the phonons and photons) are found not only happening near the center of the Brillouin zone (in the long-wavelength limit) at acoustic frequencies, but also being able to appear in the whole Brillouin zone at optical frequencies. Appearing of these phonon-polaritons may provide a way to design a new type of acousto-optic devices. 相似文献
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We studied the propagation of an electromagnetic (EM) wave in a piezoelectric superlattice. Because of the piezoelectric effect, a transverse polarization can be induced by a longitudinal wave which couples strongly to the EM wave in some particular frequency regions, resulting in the creation of a new type of polariton that does not exist in ionic crystals. The forbidden band associated with the polariton is not due to the Bragg reflection, but rather to the coupling. 相似文献
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A. V. Chaplik 《JETP Letters》2014,100(4):262-264
The spectrum of plasma oscillations in a lateral superlattice of massless Dirac electrons has been calculated in the weak coupling approximation. The intensity of absorption of electromagnetic waves by plasmons of the superlattice at frequencies near the edges of band gaps has been found. 相似文献
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S. V. Kryuchkov E. I. Kukhar’ V. A. Yakovenko 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(12):1679-1681
The effect of the mutual rectification of two electromagnetic waves with perpendicular polarization planes in a superlattice
based on graphene was investigated. It was shown that, due to the nonadditive nature of the electronic spectrum of a superlattice
based on grapheme, a constant term of current arises along its axes. The dependence of the constant of current density on
the intensity of an electromagnetic wave is oscillatory in nature. 相似文献
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The effect of mutual rectification of two electromagnetic waves in a graphene superlattice is studied for a cnoidal wave polarized along the superlattice axis and a sinusoidal wave polarized along the orthogonal direction. An expression for the density of the direct current generated by mixing of these waves is obtained. The direct current is studied as a function of the cnoidal wave amplitude. The possibility of varying both the value and the direction of the direct current with varying the cnoidal wave amplitude is shown. 相似文献
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The phonon-polariton behaviors of two-dimensional piezoelectric phononic crystals (PPCs) were studied using the plane wave expansion method. The governing equations combine Maxwell's equations and Newton's equations of motion. A mode-repulsion can be formed by strong coupling between electromagnetic (EM) waves and elastic waves in the vicinity of the center of the first Brillouin zone for PPC that comprises piezoelectric material and with opposite polarization in different periodically organized areas. Take a 2D ZnO PPC as a numerical example, it was decoupled into two independent groups. One refers to the mixed mode of the in-plane elastic waves and the transverse-magnetic (TM) mode EM waves. The other group refers to the mixed mode of the out-of-plane elastic waves and the transverse-electric (TE) mode EM waves. Coupling repulsion is also observed in these two groups. 相似文献
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Otto Schwelb 《Applied Physics A: Materials Science & Processing》1976,9(2):165-170
Relationships between complex power flow pseudo energy, propagation constant and complex frequency are presented for acoustic
waves in piezoelectric media. These relationships are essentially energy-power equations which apply to anisotropic, nonconservative,
dispersive, linear systems, analogous to those obtained by Chorney and Penfield for guided electromagnetic waves. At vanishing
piezoelectric coupling the powermode theorems split into a proper electromagnetic set and a proper mechanical set. By differentiating
the power-mode equations with respect to the complex frequency further results are obtained linking the group velocity with
power flow and energy storage. Conclusions may be drawn from these expressions regarding the signature of the dispersion (forward
or backward waves). The equipartition of pseudo energy is established at cut-off, and the vanishing of the complex power flow
at resonance. Examples including wave propagation in lossless and lossy media are included. 相似文献
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The properties of phonon-polaritons in one-dimensional undoped and ion-doped periodically poled superlattice lithium niobate (PPLN) crystals are studied theoretically. In this paper, we focus on the case that the electric field vector of the electromagnetic wave is parallel to the acoustic propagation vector. The phonon-polaritons are products of the coupling between electromagnetic and acoustic waves of mutually perpendicular propagations. Based on the theory of the phonon-polariton in PPLN, we investigate the phonon-polariton in ion-doped PPLN. The effects of the duty cycle and the impurities upon the properties of phonon-polaritons are discussed in detail. Some potential applications are also discussed. 相似文献
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It is shown from the exact equations for transverse electromagnetic waves propagating in a superlattice that in the long-wavelength limit the superlattice has the optical properties of a conventional uniaxial medium. This result is used to derive the dispersion equations for polaritons at single and double interfaces between superlattices and ordinary media. 相似文献
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d'Alembert equation written for the electromagnetic waves propagating in the graphene superlattice is discussed. The chaotic behavior of the electrons in graphene superlattice is studied by the Melnikov method. Dynamic chaos of electron in graphene superlattice is shown to appear for certain intervals of amplitudes of preset alternate current. The frequency dependence of the critical amplitude of alternate current above which would be a chaos is investigated. 相似文献
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F. Ş. Boydağ Sh. V. Mamedov V. A. Alekperov Y. Lenger Özcanli 《Optics and Spectroscopy》2003,95(2):225-229
The interaction between a solitary electromagnetic wave and a narrow layer with an increased electron concentration in a semiconductor superlattice in a preset uniform alternating electric field directed along the superlattice axis is investigated. The model of the electron energy spectrum in the superlattice is chosen in the strong coupling approximation taking into account the second harmonic. It is shown that, for certain relations between the amplitude and frequency of the alternating electric field, a solitary electromagnetic wave approaching the layer with an increased electron concentration can be trapped by this layer. 相似文献
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Interaction between an rf electromagnetic field and the Fe/Cr superlattice placed in a rectangular waveguide so that a high-frequency
current passes in the plane of superlattice layers is considered. The transmission coefficient versus the magnetic field strength
is found at centimeter waves, and a correlation between this dependence and the field dependence of the dc magnetoresistance
is established. It is shown that a change in the transmission coefficient may greatly exceed the giant magnetoresistance of
the superlattice. The frequency dependence of the microwave measurements has an oscillatory character. The oscillation frequencies
are analyzed in terms of wavelet transformation. Two types of oscillation periods are found to exist, one of which corresponds
to the resonance of waves traveling in the superlattice along the direction parallel to the narrow wall of the waveguide. 相似文献
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介电体超晶格是一种新型的有序微结构材料.它具有通常均质材料所不具有的独特优异性能,展现出重要的应用前景.文章介绍了南京大学研究组关于介电体超晶格研究所取得的进展,如将多个光参量过程集成于一块介电体超晶格之中获得了多波长激光同时输出,研制成超晶格全固态三基色激光器原型,在介电体超晶格中将拉曼散射强度增强到104-105倍,用超晶格研制的器件填补了体波超声器件从几百MHz到几千MHz的空白频段,发现了微波与超晶格振动的强烈耦合以及极化激元(polariton)的激发与传播等. 相似文献
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介电体超晶格是一种新型的有序微结构材料.它具有通常均质材料所不具有的独特优异性能,展现出重要的应用前景.文章介绍了南京大学研究组关于介电体超晶格研究所取得的进展,如将多个光参量过程集成于一块介电体超晶格之中获得了多波长激光同时输出,研制成超晶格全固态三基色激光器原型,在介电体超晶格中将拉曼散射强度增强到104—105倍,用超晶格研制的器件填补了体波超声器件从几百MHz到几千MHz的空白频段,发现了微波与超晶格振动的强烈耦合以及极化激元(polariton)的激发与传播等. 相似文献
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Mutual rectification of two electromagnetic waves, one of which is a weak sinusoidal wave and the other of which is a cnoidal wave, is considered. An expression for the constant component of the density of a current arising in a superlattice in the presence of these waves is obtained. The dependence of the constant component of the current density on the amplitude of the cnoidal wave is analyzed. The case where the sinusoidal wave frequency is twice as large as the cnoidal wave frequency is considered in detail. 相似文献
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A. B. Rinkevich L. N. Romashev V. V. Ustinov 《Journal of Experimental and Theoretical Physics》2000,90(5):834-841
The rf magnetoresistance of Fe/Cr superlattices is studied for two orientations of the current: parallel and across the superlattice layers. A mutually single-valued correspondence is established between the relative magnetoresistance measured at dc current and the change in the transmission coefficient of electromagnetic waves in the magnetic field. When rf currents flow across the layers, the relative change in the signal amplitude is proportional to twice the change in the electrical resistance of the superlattice and is of opposite sign. It is shown that the rf losses are determined by the surface resistance which is proportional to the superlattice thickness and inversely proportional to its conductivity. An equation is derived for the rf electric field distribution in the superlattice. It is established that when the thickness of the superlattice is small compared with the skin layer depth, field and current components which penetrate through the entire superlattice exist. 相似文献
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将带有LCR分流电路的压电陶瓷片对贴在铝和环氧树脂组成的声子晶体结构中.使智能材料的机械振动与压电陶瓷的压电效应耦合起来,推导出机械振动在压电陶瓷片上的等效附加应力;使LCR分流电路中的电磁振荡效应和声子晶体的能带特性有机结合,计算了在分流电路作用下智能材料扭转和弯曲振动的带隙特性,研究了电阻、电感、电容元件的改变对压电声子晶体智能材料带隙的影响.研究结果表明:在合理尺寸下,随着分流电路中电阻值的增大,带隙的频率范围变宽,但衰减幅值有所降低;电感和电容值的增大都可以使带隙向低频移动,带隙的衰减幅值随着电感值的增大而升高,但随着电容值的增大而降低.从而给压电声子晶体智能材料减震降噪的控制提供了一种新思路. 相似文献