Extended Lagrangian formalisms for dyons and some applications to solid systems under external fields

We analyze the conditions of the electromagnetic potentials for systems with electric and magnetic charges and the Lagrangian theory with these potentials. The constructed Lagrangian function is valid for obtaining the field equations and the extended Lorentz force for dyonic charges for both relativistic particles in vacuum and non-relativistic entities in solids. In a second part, with the one-body Hamiltonian of independent particles in external fields, we explore some dual properties of the dyonic system under external fields. We analyze the possible diamagnetic (and ‘diaelectric’) response of magnetic monopoles under a weak and constant electromagnetic field and the theory of Landau levels in the case of magnetic charges under strong electromagnetic constant fields.     

Dispersion behavior of electromagnetic wave near the resonance in 1D magnetized ferrite photonic crystals

In the present article, we have analyzed the dispersion of electromagnetic wave in the one dimensional magnetized ferrite photonic crystals near the resonance in the permeability of the constituent materials for transverse magnetization in the transverse electric mode. The dispersion relation is obtained by transfer matrix method. It is observed that in the vicinity of resonant frequency, large numbers of oscillations occur in the normalized Bloch wave number. These oscillations in the Bloch wave number are strongly dependent on external magnetic fields, filling factor, and damping constant. The frequency regime of these oscillations is found to be shifted in higher frequency range with increase in the magnitude of the magnetic fields. With increase in the filling factor keeping length of periods fixed, number of oscillations is found to be increased. Near the resonance, effect of incident angle is negligible. It is demonstrated that these nearly equidistant oscillations occurring in the vicinity of resonance may be used for making filter in micro wave frequency range.     

Tuning the bandgaps in a magnonic crystal–ferroelectric–magnonic crystal layered structure

A dispersion relation has been obtained for the hybrid electromagnetic spin wave in a magnonic crystal–ferroelectric–magnonic crystal layered structure. The mechanisms of the bandgap formation in this structure have been revealed, and the ability to double tune bandgap characteristics by means of the electric and magnetic fields has been shown.     

Extraordinary THz transmission through subwavelength semiconductor slits under antiparallel external magnetic fields

We theoretically study the resonant transmission of electromagnetic waves at the THz frequencies through subwavelength semiconductor slits under external static magnetic fields. The dispersion relations of the surface plasmon polaritons (SPPs) inside a subwavelength slit are analytically derived. It is found that the SPPs propagating along one direction and its reverse are symmetric when parallel external magnetic fields are applied, but are asymmetric when antiparallel external magnetic fields are applied. The transmission properties of periodic subwavelength semiconductor slit arrays with the antiparallel magnetic fields in each unit cell are investigated by the mode expansion technique. The two significant transmission characteristics are observed: (i) The resonant peaks are redshifted with increasing external magnetic fields; (ii) The transmissions in the two opposite directions through the slit arrays are asymmetric. The origin of the transmission asymmetry is reasonably explained by the magnetic-field induced asymmetric SPP propagation losses.     

Ion surface cyclotron waves at plasma-metal interfaces

The dispersion properties of slow electromagnetic surface waves propagating across a constant external magnetic field and along a plane plasma-metal interface at harmonics of the ion cyclotron frequency are studied. The motion of the plasma particles is described by a Vlasov-Boltzmann kinetic equation. The effects of the plasma size, the dielectric permittivity of the transition region between the plasma and metal, and the magnitude of the constant external magnetic field on the dispersion characteristics of ion surface cyclotron waves are studied. Zh. Tekh. Fiz. 69, 83–89 (October 1999)     

周期性磁谐振材料本构参数的理论分析

将薄的磁谐振介质板等效为面磁流, 利用周期性边界条件, 给出了面磁流的指数形式. 通过计算无穷个面磁流在不同空间位置上产生的总电场和总磁场, 推导出了周期性磁谐振人工材料的色散关系和布洛赫阻抗, 进而获取了布洛赫本构参数的理论计算公式. 由于考虑了磁谐振人工材料中的电反谐振对布洛赫介电常数和磁导率的影响, 所以基于仿真实验的布洛赫本构参数的提取值和布洛赫本构参数理论预测值之间的误差很小, 这说明本文推导的布洛赫本构参数的理论计算公式在描述周期性磁谐振材料的电磁特性方面是十分有效的. 这些理论公式将在解释磁谐振现象、设计和优化周期性磁谐振材料等方面提供重要的理论依据. 关键词： 周期性结构 磁谐振 布洛赫本构参数 面磁流     

磁光平面波导的单向传播特性

表面磁等离子体(surfacemagnetoplasmons,SMPs)是一种在电介质和偏置磁场作用下磁光材料界面处传播的近场电磁波.其独特的非互易传播特性引起了大量科研工作的关注,但在具体的波导结构设计上仍存在很多问题.本文研究了一种银-硅-磁光材料的3层平面波导结构,SMPs在磁光材料和硅的界面处传播,发现在特定的频率范围内,SMPs的基模及高阶模式均具有正向或反向的单向传播特性.分别计算了旋磁与旋电材料平面波导的色散方程,研究了硅层厚度与外加磁场对能带结构及SMPs单向传播区域的影响,发现无论是旋磁或旋电材料的结构,硅层厚度的增加使高阶模式使高阶模式出现在更低的频率位置,使单向传输带宽变小甚至消失,外加磁场的变大使磁光材料的能带结构频率增大的同时带隙中也引入了高阶模式.计算了2种磁光材料平面波导的正向和反向的单向传播带宽宽度,发现旋磁材料YIG的单向SMPs模式出现在GHz波段,最大单向带宽可达到2.45 GHz;旋电材料InSb的单向SMPs模式出现在THz波段,最大单向带宽达到3.9 THz.     

Interaction of a surface magnetostatic wave with an inhomogeneous granular HTSC medium

In the present paper the dispersion properties of surface magnetostatic waves (SMSWs) propagating in a stratified structure, ferrite film—high-temperature superconducting layer, have been investigated. The problem of SMSW propagation in an inhomogeneous stratified medium has been solved and the dispersion equation has been obtained. In the solution of this problem, the granular nature of the high-temperature superconducting (HTSC) medium and the exposure to a constant magnetization field have been taken into account. Upon exposure to the constant magnetic field the HTSC film becomes an inhomogeneous anisotropic medium with respect to a variable magnetic field. The nonhomogeneous wave equation describing the SMSW field in a granular HTSC medium has been solved by the method of sequential iterations. Corrections for the SMSW velocity and attenuation, calculated with the use of the exact dispersion equation, are significant in comparison with previously obtained approximate values and exceed 20 and 40%, respectively. The method of analyzing electromagnetic fields in inhomogeneous granular high-temperature media can be used to solve some other problems, where spatially inhomogeneous HTSC media are used. Tomsk State University of Control Systems and Radioelectronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 45–48, April, 1999.     

Axisymmetric Waves in Re-Entrant Cavities

We employ a well-established method to determine the dispersion properties of transverse magnetic and transverse electric waves in re-entrant cavities. We assume that the waveguide structure consists of a large number of identical cavities in order that the Floquet theorem could be applied to describe the electromagnetic field in an empty cylinder. Furthermore, we describe the electromagnetic field in each cavity region by an eigenfunction expansion for standing waves. Inferring boundary conditions leads to a system of two infinite sets of equations, which is solved numerically by truncation. A numerical code has been developed to calculate the dispersion relation and the electromagnetic field components. Numerical results are presented for several waveguide geometries, including the case of the real gyrotron beam-tunnel geometry. A comparison with already established codes is made.     

Manipulation of Persistent Spin Helix States by Weak External Magnetic Fields

We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semi- conductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit coupling. We show that in the presence of weak external magnetic fields, some basic properties of a persistent spin helix state, including the dispersion relation between the decay time and the magnitude of the wavevector, the maximum decay time and the value of the characteristic magnitude of the wavevector at which the maximum decay time occurs, will all depend sensitively on the directions of applied external magnetic fields.     

部分填充手征等离子体波导的电磁波

 把麦克斯韦方程和电磁场分解成横向和纵向分量, 导出了简明的一般性的手征等离子体填充的任意截面波导的波动方程和横向纵向场的关系式。对于部分填充手征等离子体波导, 导出了它的色散方程。这一方程的数值解给出了HE₁₁, EH₀₁和HE₂₁模式的色散图。随着手征等离子体填充面积的增大, EH₀₁模式的色散曲线向更高的频率移动。随着手征导纳的增加, 传播常数减小。     

等离子体填充波纹波导中低频模式特性分析

采用等离子体流体模型和线性场理论，导出了在强引导磁场下，一无限薄环形等离子体加载 波纹波导中电磁波传播的色散关系.数值计算并分析了在不同的等离子体填充密度下，低频 等离子体模式的色散特性和行波管的小信号增益.研究发现，低频等离子体模式可与相对论 电子束发生同步互作用使高频信号放大.同时，在无限薄环形等离子体填充条件下，波纹波 导中的低频等离子体模式严格满足Floquet定理所要求的周期性，其上截止频率不再受到等 离子体频率的限制，当密度较大时，等离子体模式还可与TM模式发生耦合. 关键词： 等离子体 波纹波导 色散关系 增益     

Surface electromagnetic waves in superconductors

Varying electromagnetic fields at the surface of a superconductor are studied by means of the boson method. It is found that the frequency of the surface electromagnetic waves satisfies a dispersion relation which is entirely controlled by the system itself.     

Field-induced magnetic transition in a mixed rare-earth aluminum garnet Er<Subscript>2</Subscript>HoAl<Subscript>5</Subscript>O<Subscript>12</Subscript>

The temperature dependence of the ac magnetic susceptibility of a single-crystal mixed rare-earth garnet Er₂HoAl₅O₁₂ has been investigated within the range from 1.8 to 300 K in a zero constant field and in applied bias fields of up to 9 T. In the absence of a constant magnetic field the magnetic susceptibility followed the Curie–Weiss law. The application of a constant magnetic field caused a magnetic phase transition, the temperature of which increased with increasing magnetic field. The temperature of the maximum of the ac magnetic susceptibility, which is a characteristic of the phase transition, did not show a noticeable dependence on the frequency of the alternating magnetic field.     

Multiharmonic fields driven adiabatic quantum pumps in nanowire structures

A dc current can be pumped through a nanostructure by two out-of-phase ac driving fields. In this approach, we investigate the pumped current properties driven by multiharmonic ac fields in nanowire structures. Considering the first five harmonics, the adiabatically pumping properties driven by approximate square, sawtooth, and triangle-shape ac waves are discussed. It is found that the pumped current varies with the phase difference in a square and sawtooth shape, respectively, under corresponding driven fields. Sinusoidal relation governs in the pump driven by a triangle-shape ac field.     

Hybrid surface magnetoplasma oscillations in the layered semiconductor-dielectric resonator

Theoretical and numerical studies of the electromagnetic properties of the layered semiconductor-dielectric structure in the external constant magnetic field is carried out. It is shown that due to removal of frequency degeneration the intertype coupling arises and as the result two new surface oscillations with near resonance frequencies arrear, their fields are orthogonal and modulated along interface semiconductor — dielectric of the orthogonal envelopes.     

Parametric Excitation of Electromagnetic Fields by two Pump Waves

A collisionless plasma in the presence of two monochromatic electric fields is considered. By means of a kinetic analysis, a dispersion relation that governs the excitation of transverse electromagnetic fluctuations is derived and analysed.     

电磁波与电离波面相互作用过程中的静磁场模和振荡电场

利用了匀速运动的均匀等离子体中电磁场的色散关系，对电磁波与由强激光驱动的运动电离波面的相互作用过程中出现的静磁模进行了研究，发现在特定的条件下振荡电场也会在该过程中出现，并确定了振荡电场产生的条件 关键词：     

Iron oxide nanopowder synthesized by electroerosion dispersion (EED) – Properties and potential for microwave applications

Magnetic nanoparticles (MNP) have attracted considerable interest in many fields of research and applied science due to their impressive properties. In the past, especially biomedical problems have promoted the development of MNPs. For technical applications e.g. wastewater treatment and absorption of electromagnetic waves, the existing synthesis approaches are too expensive and/or the producible quantities are too low. In this work we present a method for simple preparation of size-controlled magnetic iron oxide nanoparticles by electroerosion dispersion (EED) of carbon steel in water. We describe the synthesis method, the laboratory installation and discuss the structural, chemical and electromagnetic properties of the synthetized EED powders as well as their applicability for microwave absorption compared to other available ferrite powders.     

Effect of cyclotron resonance on the indirect exchange between localized magnetic moments

The effect of the simultaneous presence of an electromagnetic and a D.C. magnetic field on the magnon dispersion relation is discussed within the s-d-model. It is found that as the radiation frequency approaches the electron cyclotron frequency there is a quenching of the carrier contribution to the spin wave dispersion equation.