arXiv subjects

R. Shavit

Publications and source records attributed to R. Shavit.

26 records · Page 2Linked to original sources

arXiv2008

Magnetoelectric oscillations in quasi-2D ferrite disk particles

In this paper we show that magnetic-dipolar-mode (MDM) oscillations of a quasi-2D ferrite disk are characterized by unique symmetry features with topological phases resulting in appearance of the magnetoelectric (ME) properties. The entire ferrite disk can be characterized as a pair of two, electric and magnetic, coupled eigen moments. However, there is no a "glued pair" of two dipoles. An external electromagnetic field in the near-field region "views" such a ME particle, as a system with a normally oriented eigen electric moment and an in-plane rotating eigen magnetic dipole moment.

cond-mat.mtrl-sci↗

arXiv2008

Eigen power-flow-density vortices of magnetostatic modes in thin ferrite disks

In confined magnetically ordered structures one can observe vortices of magnetization and electromagnetic power flow vortices. There are topologically distinct and robust states. In this paper we show that in a normally magnetized quasi-2D ferrite disk there exist eigen power-flow-density vortices of magnetic-dipolar-mode oscillations. Because of such circular power flows, the oscillating modes are characterized by stable magnetostatic energy states and discrete angular moments of the wave fields. We show that the power-flow-density vortices of magnetostatic modes can be excited by electromagnetic fields of a microwave cavity. There is a clear correspondence between the power-flow-density vortex structures in a ferrite disk derived from an analytical solution of the magnetostatic-wave spectral problem and obtained by the numerical-simulation electromagnetic program.

cond-mat.mtrl-sci↗

arXiv2007

Electric self inductance of quasi-2D 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-2D ferrite disk show there are the double-valued-function loop magnetic currents which may produce eigen electric fields and hence eigen electric fluxes through the loop. In this case one can definitely introduce the notion of the 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 eigen electric fluxes. These fluxes are very sensitive to permittivity parameters of materials abutting to the 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.

cond-mat.mtrl-sci↗

arXiv2007

Eigen electric moments of magnetic-dipolar modes in quasi-2D ferrite disk particles

A property associated with a vortex structure becomes evident from an analysis of confinement phenomena of magnetic oscillations in a quasi-2D ferrite disk with a dominating role of magnetic-dipolar (non-exchange-interaction) spectra. The vortices are guaranteed by the chiral edge states of magnetic-dipolar modes which result in appearance of eigen electric moments oriented normally to the disk plane. Due to the eigen-electric-moment properties, a ferrite disk placed in a microwave cavity is strongly affected by the cavity RF electric field with a clear evidence for multi-resonance oscillations. For different cavity parameters, one may observe the "resonance absorption" and "resonance repulsion" behaviors.

cond-mat.mtrl-sci↗

arXiv2007

A new concept and design of ferrite-based microwave vortex devices

In microwave resonant systems with ferrite samples, one becomes faced with specific phase relations for the electromagnetic fields. Such specific phase relations may lead to appearance of nontrivial states: electromagnetic vortices. This paper provides some general ideas and design principles for microwave devices with the field vortex structures.

physics.class-ph↗

arXiv2004

Mesoscopic quantized properties of magnetic-dipolar-mode oscillations in disk ferromagnetic particles

Magnetic dipolar mode or magnetostatic (MS) oscillations in ferrite samples have the wavelength much smaller than the electromagnetic wavelength at the same frequency and, at the same time, much larger than the exchange interaction spin wavelength. This intermediate position between the electromagnetic and spin wave (exchange interaction) processes reveals very special behaviors of the geometrical effects. It was shown recently that magnetic dipolar mode oscillations in a normally magnetized ferromagnetic disk are characterized by discrete energy levels resulting from the structural confinement. In this article we give results of the energy spectra in MS wave ferrite disks taking into account nonhomogeneity of the internal DC magnetic field.

cond-mat.mes-hall↗

arXiv2003

Energy Spectra of Magnetostatic Oscillations in Ferrite Disk Resonators

Ferromagnetic resonators with short-wavelength, so-called magnetostatic (MS), oscillations can be considered in microwaves as point (with respect to the external electromagnetic fields) particles. It was shown recently [E. O. Kamenetskii, Phys. Rev. E, 63, 066612 (2001)] that MS oscillations in a small ferrite disk resonator can be characterized by a discrete spectrum of energy levels. This fact allows analyzing the MS oscillations similarly to quantum mechanical problems. In this paper we give the results of energy spectrum calculations for MS oscillations in a ferrite disk resonator.

cond-mat.mes-hall↗

arXiv2003

Magnetic artificial atoms based on thin-film ferrite disk particles

Semiconductor quantum wells can be considered as an example of artificial atoms. Following the ideas used in the effective-mass theory, one can describe electron states in the quantum-well structure based on the Schrodinger-like equation for the envelope function. In recent years, there has been a renewed interest in high frequency dynamic properties of finite size magnetic structures. In a series of new publications, confinement phenomena of high-frequency magnetization dynamics in magnetic particles have been the subject of much experimental and theoretical attention. Till now, however, there are no phenomenological models of a ferrite particle with high-frequency magnetization dynamics that use the effective-mass approximation and the Schrodinger-like equation to analyze energy eigenstates of a whole ferrite-particle system, similarly to semiconductor quantum wells. Magnetostatic (MS) oscillations in ferrite samples have the wavelength much smaller than the electromagnetic wavelength at the same frequency and, at the same time, much larger than the exchange-interaction spin wavelength. This intermediate position between the pure electromagnetic and spin-wave (exchange-interaction) processes reveals very special behaviors of the geometrical effects. The confined effects for MS oscillations in normally magnetized thin-film ferrite disks demonstrate very unique properties of artificial atomic structures.

cond-mat.mes-hall↗