144 research outputs found
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
The anapole moments in disk-form MS-wave ferrite particle
The anapole moments describe the parity-violating parity-odd,
time-reversal-even couplings between elementary particles and the
electromagnetic (EM) field. Surprisingly, the anapole-like moment properties
can be found in certain artificially engineered physical systems. In
microwaves, ferrite resonators with multi-resonance magnetostatic-wave
(MS-wave) oscillations may have sizes two-four orders less than the free-space
EM wavelength at the same frequency. MS-wave oscillations in a ferrite sample
occupy a special place between the pure electromagnetic and spin-wave
(exchange) processes. The energy density of MS-wave oscillations is not the
electromagnetic-wave density of energy and not the exchange energy density as
well. These microscopic oscillating objects -- the particles -- may interact
with the external EM fields by a very specific way, forbidden for the classical
description. To describe such interactions, the quantum mechanical analysis
should be used. The presence of surface magnetic currents is one of the
features of MS oscillations in a normally magnetized ferrite disk resonator.
Because of such magnetic currents, MS oscillations in ferrite disk resonators
become parity violating. The parity-violating couplings between disk-form
ferrite particles and the external EM field should be analyzed based on the
notion of an anapole moment.Comment: 20 pages, 2 figures, PDF (created from MS-Word
Azimuthally unidirectional transport of energy in magnetoelectric fields. Topological Lenz effect
Magnetic dipolar modes (MDMs) in a quasi 2D ferrite disk are microwave energy
eigenstate oscillations with topologically distinct structures of rotating
fields and unidirectional power flow circulations. At the first glance, this
might seem to violate the law of conservation of an angular momentum, since the
microwave structure with an embedded ferrite sample is mechanically fixed.
However, an angular momentum is seen to be conserved if topological properties
of electromagnetic fields in the entire microwave structure are taken into
account. In this paper we show that due to the topological action of the
azimuthally unidirectional transport of energy in a MDM resonance ferrite
sample there exists the opposite topological reaction on a metal screen placed
near this sample. We call this effect topological Lenz effect. The topological
Lenz law is applied to opposite topological charges, one in a ferrite sample
and another on a metal screen. The MDM originated near fields, the
magnetoelectric (ME) fields, induce helical surface electric currents and
effective charges on a metal. The fields formed by these currents and charges
will oppose their cause
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