E. O. Kamenetskii

ON THE TECHNOLOGY OF MAKING CHIRAL AND BIANISOTROPIC WAVEGUIDES FOR MICROWAVE PROPAGATION

We introduce an idea for a novel class of artificial materials suitable for chiral and bianisotropic waveguide structures. Fabrication of such waveguides can be achieved using modern planar technology. Chiral and bianisotropic waveguides described in this article are based on a composition of magnetostatic wave (MSW) resonators. Because of the small sizes of MSW resonators the concentration of the particles may be very high. The resonance frequency of MSW resonators may be tuned via a bias magnetic field. Therefore, we can develop a method of achieving chirality control.

Novel microwave near-field sensors for material characterization, biology, and nanotechnology

The wide range of interesting electromagnetic behavior of contemporary materials requires that experimentalists working in this field master many diverse measurement techniques and have a broad understanding of condensed matter physics and biophysics. Measurement of the electromagnetic response of materials at microwave frequencies is important for both fundamental and practical reasons. In this paper, we propose a novel near-field microwave sensor with application to material characterization, biology, and nanotechnology. The sensor is based on a subwavelength ferrite-disk resonator with magnetic-dipolar-mode (MDM) oscillations. Strong energy concentration and unique topological structures of the near fields originated from the MDM resonators allow effective measuring material parameters in microwaves, both for ordinary structures and objects with chiral properties.

Interaction of magnetic-dipolar modes with microwave-cavity electromagnetic fields

We discuss the problem of magnetic-dipolar oscillations combined with microwave resonators. The energy density of magnetic-dipolar or magnetostatic (MS) oscillations in ferrite resonators is not the electromagnetic-wave density of the energy and not the exchange energy density as well. This fact reveals very special behaviors of the geometrical effects. Compared to other geometries, thin-film ferrite disk resonators exhibit very unique interactions of MS oscillations with the cavity electromagnetic fields. MS modes in a flat ferrite disk are characterized by a complete discrete spectrum of energy levels. The staircase demagnetization energy in thin-film ferrite disks may appear as noticeable resonant absorption of electromagnetic radiation. Our experiments show how the environment may cause decoherence for magnetic oscillations. Another noticeable fact is experimental evidence for eigen-electric-moment oscillations in a ferrite disk resonator.

Tellegen particles and magnetoelectric metamaterials

In 1948 Tellegen [Philips Res. Rep. 3, 81 (1948)] suggested that an assembly of the lined up electric-magnetic dipole twins can construct a new type of an electromagnetic material. Until now, however, the problem of creation of the Tellegen medium is a subject of strong discussions. An elementary symmetry analysis makes questionable an idea of a simple combination of two (electric and magnetic) dipoles to realize local materials with the Tellegen particles as structural elements. In this paper we show that in search of sources with local junctions of the electrical and magnetic properties one cannot rely on the induced parameters of small electromagnetic scatterers. No near-field electromagnetic structures and no classical motion equations for point charges give a physical basis for realization of sources with a local junction of the electrical and magnetic properties. We advance a hypothesis that local magnetoelectric (ME) particles should be physical objects with eigenmode oscillation spectra and noncla...

Helical-mode magnetostatic resonances in small ferrite particles and singular metamaterials.

Small ferrite-disk particles with magnetostatic (magneto-dipole) oscillations are characterized by the topological-phase states-the vortex states. In a recently published paper (Kamenetskii et al 2010 Phys. Rev. A 81 053823), it was shown that such magnetic vortices act as traps, providing purely subwavelength confinement of electromagnetic fields. The symmetry properties of magnetostatic-vortex ferrite disks allow one to propose new-type subwavelength microwave structures. In this paper it is demonstrated that the unique topological properties of the fields in a ferrite disk are intimately related to the symmetry breaking effects of magnetostatic oscillations. This analysis is based on postulates about a physical meaning of the magnetostatic-potential function ψ(r, t) as a complex scalar wavefunction, which presumes a long-range phase coherence in magnetic dipole-dipole interactions. The proper solutions are found based on an analysis of magnetostatic-wave propagation in a helical coordinate system. It is shown that while a composition of two helical waves may acquire a geometrical phase over-running of 2π during a period, every separate helical wave has a dynamical phase over-running of π and so behaves as a double-valued function. This results in the appearance of helical-mode magnetostatic resonances in quasi-2D ferrite disks. The solutions give magnetostatic-wave power-flow-density vortices with cores at the disk center and azimuthally running waves of magnetization. The near fields of magnetostatic-vortex ferrite-disk particles are characterized by space-time symmetry violation. For incident electromagnetic waves, such particles, with sizes much less than the free-space electromagnetic wavelength, appear as local singular regions. From the properties of a composition of magnetostatic-vortex ferrite-disk particles, one may propose novel metamaterials-singular metamaterials.

Topological-phase effects and path-dependent interference in microwave structures with magnetic-dipolar-mode ferrite particles

Different ways exist in optics to realize photons carrying nonzero orbital angular momentum. Such photons with rotating wave fronts are called twisted photons. In microwaves, twisted fields can be produced based on small ferrite particles with magnetic-dipolar-mode (MDM) oscillations. Recent studies showed strong localization of the electric and magnetic energies of microwave fields by MDM ferrite disks. For electromagnetic waves irradiating MDM disks, these small ferrite samples appear as singular subwavelength regions with time and space symmetry breakings. The fields scattered by a MDM disk are characterized by topologically distinctive power-flow vortices and helicity structures. In this paper we analyze twisted states of microwave fields scattered by MDM ferrite disks. We show that in a structure of the fields scattered by MDM particles, one can clearly distinguish rotating topological-phase dislocations. Specific long-distance topological properties of the fields are exhibited clearly in the effects of path-dependent interference with two coupled MDM particles. Such double-twisted scattering is characterized by topologically originated split-resonance states. Our studies of topological-phase effects and path-dependent interference in microwave structures with MDM ferrite particles are based on numerical analysis and recently developed analytical models. We present preliminary experimental results aimed to support basic statements of our studies.

Magnetic-dipolar and electromagnetic vortices in quasi-2D ferrite discs.

Magnetic-dipolar-mode (MDM) oscillations in a quasi-2D ferrite disc show unique dynamical symmetry properties resulting in the appearance of topologically distinct structures. Based on the magnetostatic (MS) spectral problem solutions, in this paper we give evidence for eigen-MS power-flow-density vortices in a ferrite disc. Due to these circular eigen-power flows, the MDMs are characterized by MS energy eigenstates. It becomes evident that the reason for stability of the vortex configurations in saturated ferrite samples is completely different from the nature of stability in magnetically soft cylindrical dots. We found a clear correspondence between analytically derived MDM vortex states and numerically modeled electromagnetic vortices in quasi-2D ferrite discs.

Electric self-inductance of quasi-two-dimensional magnetic-dipolar-mode ferrite disks

An electric current flowing around a loop produces a magnetic field and hence a magnetic flux through the loop. The ratio of the magnetic flux to the electric current is called the (magnetic) self-inductance. Can there be a dual situation with a magnetic current flowing around a loop and producing an electric field and hence an electric flux through the loop? Following the classical electrodynamics laws an answer to this question should be negative. Nevertheless, special spectral properties of magnetic-dipolar modes in a quasi-two-dimensional ferrite disk show that there are the double-valued-function loop magnetic currents which may produce eigenelectric fields and hence eigenelectric fluxes through the loop. In this case one can definitely introduce a notion of an electric self-inductance as the ratio of the electric flux to the magnetic current. In this paper we show experimentally that in the magnetic-dipolar-mode ferrite disks there exist eigenelectric fluxes. These fluxes are very sensitive to the permittivity parameters of materials abutting to a ferrite disk. Dielectric samples above a ferrite disk with a higher permittivity than air confine the electric field closely outside the ferrite, thereby changing the loop magnetic currents and thus transforming the magnetic-dipolar-mode oscillating spectrum.

Electric and magnetic polarization properties of ferrite magnetoelectric particles

In this paper, new experimental results of the microwave spectral properties of quasistatic magnetoelectric (ME) particles based on small ferrite resonators with linear-form surface electrodes have been illustrated. Existence of local coupling between electric and magnetic dipolar polarizations, which can be essential for realization of the so-called bianisotropic materials, has been proved. Also, a method of boosting the ME effect in a particle has been suggested.

Magnetostatically Controlled Bianisotropic Media: A Novel Class of Artificial Magnetoelectric Materials

Recently an idea of a novel class of artificial bianisotropic materials has been introduced. Theoretical analysis sufficiently demonstrates magnetoelectric effect in proposed media. Now it becomes clear that this idea would make it possible to realize (both on the theoretical and experimental levels) many different bianisotropic material parameters that we have not been able to create before. Further development of these materials may be very productive in terms of new linear and nonlinear effects. For practical realization of such artificial media we can use planar technology well developed for magnetostatic wave (MSW) devices.