Electromagnetic waves reflected from the plate of a magnetic with a ferromagnetic spiral

The spectrum of coupled spin and electromagnetic waves is obtained for a magnetic with a ferromagnetic spiral structure determined by nonuniform exchange and relativistic interactions. It is shown that resonant interaction between spin and electromagnetic waves is possible. The electromagnetic wave reflectance from the plate of a magnetic with a ferromagnetic spiral is calculated for different spiral angles.     

Spatial dynamics of hybrid electromagnetic spin waves in a lateral multiferroic microwaveguide

Regimes of the formation of spatial structures at the propagation of hybrid electromagnetic spin waves in a system of laterally coupled multiferroics, which consist of parallel ferromagnetic microwaveguides with a ferroelectric layer, are studied experimentally and theoretically. Brillouin spectroscopy measurements at frequencies near the ferromagnetic resonance by the method of selection of mode patterns reveal a sharp increase in the spatial scales of transfer of power between microwaveguides. The calculations of the characteristics of propagation of electromagnetic spin wave in a lateral multiferroic structure with a finite width show that energy exchange between films is due to the features of intermodal coupling between waves. Higher transverse modes and electric-field-induced transformation of spectra of the electromagnetic spin waves in the adjacent multiferroics are studied experimentally and numerically.     

Lorentz-boosted evanescent waves

Polarization, spin, and helicity are important properties of electromagnetic waves. It is commonly believed that helicity is invariant under the Lorentz transformations. This is indeed so for plane waves and their localized superpositions. However, this is not the case for evanescent waves, which are well-defined only in a half-space, and are characterized by complex wave vectors. Here we describe transformations of evanescent electromagnetic waves and their polarization/spin/helicity properties under the Lorentz boosts along the three spatial directions.     

Coupled spin, elastic, and electromagnetic waves in the magnetic of a ferromagnetic spiral phase

The spectrum of coupled spin, elastic, and electromagnetic waves in the magnetic of a ferromagnetic spiral phase is investigated. The frequency dependences of the reflection coefficient of electromagnetic waves from the surface of a semi-infinite magnet for different angles of the spiral are obtained. An acoustic analog of the Faraday effect in the magnetics of a ferromagnetic spiral phase is considered.     

Micromorphic Electromagnetic Theory and Waves

This paper introduces a continuum microelectromagnetic theory (also called micromorphic electromagnetic theory), to discuss electromagnetic phenomena in bodies with microstructures. Balance laws of microelectromagnetic media of the first-grade are given. Constitutive equations are developed. The field equations are obtained . It has been shown that, this theory gives rise to several new vector and tensor waves. A theorem of conservation of energy (Poynting type) is proved. Dispersion relations are obtained for both vector and tensor waves. Relations of tensor waves to microscopic phenomena (such as spin waves) are discussed.     

Eigenwaves in a two-component system of particles with nonzero magnetic moments

Two-component systems of particles with nonzero intrinsic magnetic moments are shown to support not only the transverse electromagnetic and longitudinal waves, but also self-consistent spin waves and waves that propagate independently in each component and degenerate into oscillations for spin-zero systems. For all types of waves, the dispersion relations are obtained by solving the quantum hydrodynamics equations and field equations in linear approximation.     

Electromagnetic waves in a rotating frame of reference

We discuss the electromagnetic measurements of rotating observers and study the propagation of electromagnetic waves in a uniformly rotating frame of reference. The phenomenon of helicity‐rotation coupling is elucidated and some of the observational consequences of the coupling of the spin of a particle with the rotation of a gravitational source are briefly examined.     

Spectra of exchange dipole electromagnetic-spin waves in asymmetric metal-insulator-ferromagnetic-insulator-metal systems

Spectra of exchange dipole electromagnetic-spin waves in tangentially magnetized asymmetric planar-layer metal-insulator-ferromagnetic-insulator-metal (MIFIM) systems were studied theoretically. It is shown that symmetry breakdown due to a difference in the permittivities of the insulating layers may substantially enhance interaction between the spin and electromagnetic waves. This improves the electrical controllability of the dispersion properties of the spin waves, for example, by varying the permittivity of one of the layers that are in contact with the ferromagnetic film. Optimal geometries of the layer structures that provide the best electrical control are suggested.     

Self-localized nonlinear surface magnetic polaritons in a ferromagnetic medium

The properties of electromagnetic waves propagating in a semibounded, nonlinear, ferromagnetic medium are investigated. It is shown that under certain conditions the interaction between the spin and electromagnetic waves results in the localization of volume polaritons near the surface. Self-localization of surface polaritons due to the nonlinear properties of the medium occurs thereby. The nonlinear Schrödinger equation for nonlinear surface and volume polaritons is derived, and the conditions under which solitons of these waves exist are determined. The wave intensity required to observe the predicted effects is estimated.     

Spin-wave spectroscopy and application of its methods to heterostructures of silicon dioxide with Co nanoparticles on a GaAs substrate

A method has been developed for determining magnetic and electrical characteristics of film nanostructures containing magnetic nanoparticles from dispersion curves of surface spin waves propagating in these nanostructures. The dispersion curves of spin waves are determined by the dynamics of the spin component described by the generalized Landau-Lifshitz equations and an alternating electromagnetic field induced by a spin wave. Since spin waves are very sensitive to inhomogeneity of magnetic parameters, spin disorder, and conductivity of an object near or inside which these waves propagate, they can be used for determining magnetic and electrical characteristics of the objects under investigation. The developed calculation method, which can be employed both in spin-wave spectroscopy and in analysis of dispersion curves obtained by other methods, has been used for determining parameters of heterostructures consisting of a SiO₂ film with Co nanoparticles on a GaAs substrate. It has been found from the shape of dispersion curves of the surface spin waves that, in the film near the interface, spins of the nanoparticles are close to a ferromagnetic ordering, whereas near the free surface, the spin orientation of nanoparticles is more chaotic. It has been revealed that a conducting layer is formed in GaAs, and the SiO₂(Co) film near the interface has an increased conductivity.     

Gradient Chiral Metamirrors for Spin‐Selective Anomalous Reflection

Metasurfaces, the phase‐engineered quasi‐2D interfaces, have attracted intensive interest due to their great capabilities in manipulating the reflection, refraction and transmission of electromagnetic waves. Here, we demonstrate the design and realization of a gradient chiral metamirror tailored for spin‐selective anomalous reflection based on the theory of Pancharatnam‐Berry phase. Asymmetric split ring resonators are employed as the basic meta‐atoms for strong circular dichroism. Dispersionless phase discontinuities are achieved by adjusting the orientation of the meta‐atoms, and spin‐dependent absorption is realized by introducing a chiral resonance. Theoretical results predict both broadband beam deflection and spin‐selective absorption for circularly polarized waves in a designer metamirror. Experimental verification of this bifunctional performance is implemented at microwave frequencies and the measured results agree well with the simulation ones. Such chiral metamirrors could pave an avenue towards spin‐selective modulation of the wavefront and might find promising applications in planar electromagnetic devices.     

Theory of ferromagnetic antiresonance in parallel configuration in metals

A solution of Maxwell equations for the propagation of electromagnetic waves in a metallic ferromagnet is presented for the region of ferromagnetic antiresonance; the magnetization vector motion is described by the Landau-Liftshitz equation, the metal sample is in the form of a flat disc statistically magnetized in its surface plane (parallel configuration). The dispersion relations for the three waves of (complex) electromagnetic spin wave origin, the surface impedance and the shifts of antiresonance point due to the damping and electrical conductivity are computed in the analytical form.     

Theoretical analysis of microwave properties of ferrite-ferroelectric magnonic crystals

Microwave properties of ferrite-ferroelectric magnonic crystals are investigated for the first time. The electric and magnetic rearrangement of the band gaps in the spectrum of proper electromagnetic spin waves in such structures is demonstrated.     

The peculiarities of coupled electromagnetic and magnetoelastic waves in antiferromagnets

A spectrum of coupled electromagnetic, spin and elastic waves in a two-sublattice antiferromagnet with weak ferromagnetism is theoretically investigated. The influence of the g-factor anisotropy and the transverse and longitudinal relaxation in magnetic subsystem on the spectrum of coupled waves is considered. The most changes of dispersion laws occurred in long-wavelength approximation and near the spin reorientation point, then the vectors of ferromagnetism and antiferromagnetism reoriented onto another crystallographic axis. It is shown that the magnetoelastic, the Dzyaloshinsky and the dipole interactions, the anisotropy of g-factor, the external magnetic field and the longitudinal susceptibility determine the activation of quasiferromagnetic waves. The dispersion laws of quasielectromagnetic and quasielastic waves can change from linear dependence to square. At large damping in magnetic subsystem, one from these modes can become the pure relaxation one.     

Spin waves in paramagnetic metals

The excitation of spin waves in paramagnetic metals by circularly-polarized electromagnetic waves is considered. An investigation is made of the effect of boundary conditions for the magnetic moment on the amplitude of the electromagnetic-spin waves in a metal. The same investigation is carried out for the surface impedance.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 7–10, January, 1974.The author acknowledges A. Ya. Blank for proposing the subject and for numerous discussions.     

Chirality Driven by Magnetic Dipole Response for Demultiplexing of Surface Waves

Surface electromagnetic waves are characterized by the intrinsic spin‐orbit interaction which results in the fascinating spin‐momentum locking. Therefore, directional coupling of light to surface waves can be achieved through chiral nanoantennas. Here, we show that dielectric nanoantenna provides chiral response with strong spectral dependence due to the interference of electric and magnetic dipole momenta when placed in the vicinity of the metal‐air interface. Remarkably, chiral behaviour in the proposed scheme does not require elliptical polarization of the pump beam or the geometric chirality of the nanoantenna. We show that the proposed ultracompact and simple dielectric nanoantenna allows for both directional launching of surface plasmon polaritons on a thin gold film and their demultiplexing with a high spectral resolution.     

Zur Behandlung kollektiver Strahlungseffekte vieler Atome

A quantization procedure using spherical electromagnetic waves with different central points is developed and used to describe the interaction of the field with a system of many atoms. For two atoms and for an infinite linear chain built by identical equidistant atoms the Hamiltonian is simplified by a transformation which in the latter case has some analogy to spin wave theory.     

立方铁磁体中的自旋波局域模

本文计算了简单立方铁磁体中由于磁性杂质的存在而形成的局域自旋波。其空间对称有s型模、p型模和d_r型模三种。求出了各类局域模的波函数和自旋偏离的相角分布,其相应的能级与参量J′S′/JS的关系均由曲线表出。其次分析了在体心立方和面心立方铁磁体中可能出现的局域模的对称类型。我们指出,s型局域自旋波是最有可能实际观测到的。作为观测局域自旋波的样品的铁磁体,其居里点应随渗杂浓度的增加而上升。按照这一判据,我们举出一些可以试用的实验样品。最后,通过总自旋量子数的分析,一般地断定了辐射场不可能激 关键词：     

Coherent control of spin precession motion with impulsive magnetic fields of half-cycle terahertz radiation

Coherent control of the precession motion of magnetizations in a single crystal YFeO3 with double half-cycle pulse terahertz waves was demonstrated. Quasiferromagnetic (0.299 THz) and quasiantiferromagnetic (0.527 THz) precession modes were selectively excited by choosing an appropriate interval of two pulses and were observed as free induction decay (FID) signals from the spin system. By observing the circularly polarized FID signals due to ferromagnetic resonance, we also succeeded in confirming directly the energy storage in the spin system and recovery from that to the electromagnetic radiation.     

Spin-injection terahertz radiation in bilayer epitaxial magnetic planar nanostructures

The generation of electromagnetic THz waves by a current is experimentally investigated in planar structures comprised of two ferromagnetic films. When the films come into contact with a thin copper rod, the current is applied to both layers. The first layer, which plays the role of an injector, polarizes the spins of the current carriers. In the second working layer, the conditions are created for spin population inversion and the generation of THz waves. At a current of 350 mA, the radiation wavelength is 16.4 THz and a power of 10 mW is reached at room temperature.