Penetration of RF Electromagnetic Field through Thin Films of La0.67Sr0.33MnO3 Manganite

2009 ◽  
Vol 152-153 ◽  
pp. 123-126
Author(s):  
A. Nosov ◽  
A. Rinkevich ◽  
I. Gribov ◽  
N. Moskvina ◽  
V. Vassiliev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Experimental Data ◽  
Electromagnetic Waves ◽  
Magnetic Ordering ◽  
Electromagnetic Properties ◽  
Local Dynamic ◽  
Frequency Range ◽  
Frequency Limit ◽  
Dc Magnetic Field

Peculiarities of penetration of electromagnetic waves through the bulk and thin film samples of the La0.67Sr0.33MnO3 manganite were investigated for the frequency range from 50 kHz to 20 MHz. Strong variations of penetration coefficient in the applied dc magnetic field were observed both for ferromagnetic and paramagnetic states. Local dynamic magnetic ordering in the paramagnetic temperature range was observed. The experimental data reveal weak dependence of electromagnetic properties on microstructure of the films. The upper frequency limit of the dynamic polaron correlations in the paramagnetic phase was estimated.

NONRECIPROCAL ELECTROMAGNETIC DEVICES IN GYROMAGNETIC PHOTONIC CRYSTALS

2013 ◽  
Vol 28 (02) ◽  
pp. 1441010 ◽  
Author(s):  
ZHI-YUAN LI ◽  
RONG-JUAN LIU ◽  
LIN GAN ◽  
JIN-XIN FU ◽  
JIN LIAN
Keyword(s):  
Magnetic Field ◽  
Band Gap ◽  
Electromagnetic Waves ◽  
Experimental Studies ◽  
Magnetic Surface ◽  
Electromagnetic Properties ◽  
Edge States ◽  
Bragg Scattering ◽  
Electromagnetic Devices ◽  
Gap Opening

Gyromagnetic photonic crystal (GPC) offers a promising way to realize robust transport of electromagnetic waves against backscattering from various disorders, perturbations and obstacles due to existence of unique topological electromagnetic states. The dc magnetic field exerting upon the GPC brings about the time-reversal symmetry breaking, splits the band degeneracy and opens band gaps where the topological chiral edge states (CESs) arise. The band gap can originate either from long-range Bragg-scattering effect or from short-range localized magnetic surface plasmon resonance (MSP). These topological edge states can be explored to construct backscattering-immune one-way waveguide and other nonreciprocal electromagnetic devices. In this paper we review our recent theoretical and experimental studies of the unique electromagnetic properties of nonreciprocal devices built in GPCs. We will discuss various basic issues like experimental instrumental setup, sample preparations, numerical simulation methods, tunable properties against magnetic field, band degeneracy breaking and band gap opening and creation of topological CESs. We will investigate the unidirectional transport properties of one-way waveguide under the influence of waveguide geometries, interface morphologies, intruding obstacles, impedance mismatch, lattice disorders, and material dissipation loss. We will discuss the unique coupling properties between one-wave waveguide and resonant cavities and their application as novel one-way bandstop filter and one-way channel-drop filter. We will also compare the CESs created in the Bragg-scattering band gap and the MSP band gap under the influence of lattice disorders. These results can be helpful for designing and exploring novel nonreciprocal electromagnetic devices for optical integration and information processing.

scholarly journals High Frequency Magnetoimpedance of FeNi/Cu/FeNi Sensitive Elements with Different Geometries

2009 ◽  
Vol 152-153 ◽  
pp. 373-376 ◽  
Author(s):  
Stanislav O. Volchkov ◽  
Andrey V. Svalov ◽  
G.V. Kurlyandskaya
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Finite Elements ◽  
Magnetic Anisotropy ◽  
Constant Magnetic Field ◽  
High Frequency ◽  
Complex Impedance ◽  
Rf Sputtering ◽  
Frequency Range

In this work magnetoimpedance (MI) behaviour was studied experimentally for Fe19Ni81(175 nm)/Cu(350 nm)/Fe19Ni81(175 nm) sensitive elements deposited by rf-sputtering. A constant magnetic field was applied in plane of the sandwiches during deposition perpendicular to the Cu-lead in order to induce a magnetic anisotropy. Sandwiches with different width (w) of FeNi parts were obtained. The complex impedance was measured as a function of the external magnetic field for a frequency range of 1 MHz to 700 MHz for MI elements with different geometries. Some of MI experimental data are comparatively analysed with finite elements numerical calculations data. The obtained results can be useful for optimization of the design of miniaturized MI detectors.

scholarly journals Быстрые и медленные электромагнитные волны в продольно намагниченном тонкопленочном ферромагнитном метаматериале

2019 ◽  
Vol 45 (23) ◽  
pp. 14
Author(s):  
М.Д. Амельченко ◽  
С.В. Гришин ◽  
Ю.П. Шараевский
Keyword(s):  
Thin Film ◽  
Electromagnetic Waves ◽  
Theoretical Study ◽  
Ferromagnetic Film ◽  
Thin Metal ◽  
Periodic Lattice ◽  
Frequency Range ◽  
Cutoff Frequencies ◽  
Left Handed ◽  
Metal Wires

The results of a theoretical study of the electrodynamic characteristics of fast and slow electromagnetic waves (EMWs) propagating in a metamaterial are presented. The metamaterial consists of a ferromagnetic film inside which a periodic lattice of thin metal wires is located. It has been established that the ferromagnetic thin-film metamaterial possesses the properties of a left-handed medium at frequencies of slow electromagnetic waves. It is shown that, in a ferromagnetic metamaterial, compared with a conventional ferromagnetic film, the cutoff frequencies of fast and slow EMWs shift to a higher frequency range, and EMWs themselves become strongly slowed waves.

Electromagnetic Properties of Bearing Cement-Based Materials

2011 ◽  
Vol 261-263 ◽  
pp. 663-668
Author(s):  
Ai Li Guo ◽  
Ri Gao ◽  
Heng Jing Ba
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Building Materials ◽  
Incident Angle ◽  
High Strength ◽  
Wave Incident ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Electromagnetic Wave Incident ◽  
Cement Based Materials

For studying absorption/bearing integration of building materials, high-strength cement-based materials were prepared by using active fly ash, silica fume and quartz, etc. Electromagnetic parameters of the cement-based materials were measured through coaxial method, and then by means of these parameters, the reflectivity of electromagnetic waves of the cement-based materials were simulated under variable electromagnetic wave incident angle (θ), frequency (f) and thickness of the material(d).The reflectivity of electromagnetic waves with 8~18GHz frequency range vertically transmitting into the cement-based materials was obtained through far field radar scattered cross-section measurement, and was compared with simulated reflectance under the same incident conditions. The results show that the high-strength cement-based materials with imaginary part of dielectric constant can consume energy of the incident electromagnetic wave. Incident angle less than 15° has little effect on the reflectivity of the cement-based materials in 2~18GHz frequency range. While the thickness of the cement-based materials is 15mm or 25mm, simulation results of the reflectivity are in good agreement with measured ones. Measured absorption peak and -10dB bandwidth increase with the increasing of thickness of the cement-based materials with compressive strength of 120.7MPa. This suggests that the cement-based materials studied in this paper have the characteristics of absorption/bearing integration.

Convective laser filamentation instability in magnetized plasma

2014 ◽  
Vol 92 (6) ◽  
pp. 504-508 ◽  
Author(s):  
M.S. Bawa’aneh ◽  
Ghada Assayed ◽  
M.R. Said ◽  
S. Al-Awfi
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Amplification Factor ◽  
Magnetized Plasma ◽  
Governing Equations ◽  
Equilibrium Plasma ◽  
Dc Magnetic Field ◽  
Density Values ◽  
Filamentation Instability ◽  
The Magnetic Field

The convective amplification of filamentation instability (FI) of electromagnetic waves traveling along the density ramp of a magnetized plasma is investigated. The generalized amplification factor of the instability in the presence of a DC–magnetic field is derived by obtaining the governing equations of the instability and using the slow-coupling technique to obtain an analytical expression for the amplification factor in weakly magnetized plasma. The result shows enhancement of the convective FI gain by the magnetic field, where the enhancement is stronger for lower equilibrium plasma density values.

MAGNETIC FIELD RESPONSES OF HARMONIC SUSCEPTIBILITIES OF HIGH TC SUPERCONDUCTOR YBCO

2006 ◽  
Vol 20 (19) ◽  
pp. 1199-1205
Author(s):  
OZER OZOGUL
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Bias Field ◽  
State Equation ◽  
Model Calculations ◽  
High Tc ◽  
Dc Magnetic Field ◽  
High Tc Superconductor ◽  
Dc Bias ◽  
Higher Harmonic

The temperature dependence of the harmonic susceptibilities has been measured on a melt textured YBCO for different amplitudes of the AC magnetic field with combination of a DC magnetic field. The model calculations have been performed on the basis of a model which incorporates the effects of the collective creep concept in a critical-state equation. The temperature dependencies of the activation energy and the critical current density chosen as U = [U0(1 - (T/Tc)4)/μ)][(Jc/J)μ - 1] and Jc = J0[(1 + (T/Tc)2)]-1/2[(1 - (T/Tc)2)]5/2 respectively have been used to explain the DC bias field and temperature dependencies of the harmonic susceptibilities. The predictions of the model for fundamental and higher harmonic susceptibilities were consistent with the experimental data.

Longitudinal Ultrasonic Attenuation in Tantalum at Frequencies up to 1 GHz

1971 ◽  
Vol 49 (3) ◽  
pp. 296-301 ◽  
Author(s):  
J. M. Perz ◽  
W. A. Roger
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Frequency Dependence ◽  
Normal State ◽  
Superconducting State ◽  
Ultrasonic Attenuation ◽  
Mean Free Path ◽  
Ultrasonic Waves ◽  
Frequency Range ◽  
Conduction Electrons

The attenuation due to interaction with conduction electrons of longitudinal sound propagating along [110] in a Ta crystal of resistance ratio 390 has been measured over the frequency range 0.46 to 1.0 GHz. The product of the wave vector q and the electronic mean free path l determined from the frequency dependence of the normal state attenuation ranges over 1.8 < ql < 3.8. The attenuation in the superconducting state in the absence of a magnetic field fits the BCS expression for 1.2 < T < Tc = 4.46 K with 2Δ(0) = 3.62 ± 0.06 kTc. The ultrasonic waves have been generated by thin film CdS transducers, and the conversion efficiency has been found to vary inversely with the active area of the transducer.

WAVES IN A RAREFIED IONIZED GAS PROPAGATED TRANSVERSE TO AN EXTERNAL MAGNETIC FIELD

1961 ◽  
Vol 39 (7) ◽  
pp. 1044-1057 ◽  
Author(s):  
Tomiya Watanabe
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Sound Waves ◽  
Ionized Gas ◽  
Frequency Limit ◽  
Electrons And Ions ◽  
Hydromagnetic Waves ◽  
Perturbed Magnetic Field

Waves being propagated in a rarefied and fully ionized gas and transverse to an external magnetic field have been studied, particularly hydromagnetic waves. Three modes of waves, in which the perturbed magnetic field is parallel to the external magnetic field, are found to be propagated. In a high-frequency limit, they tend to electromagnetic waves, electron sound waves, and ion sound waves. In the condition that the Alfvén velocity is greater than the ion sound velocity but smaller than the light velocity, the last mode tends to a hydromagnetic wave in the low-frequency limit. The other two modes of waves can be propagated only at frequencies higher than the critical frequencies, both of which almost equal the electron plasma frequency. The condition that hydromagnetic waves should be attenuated severely due to collisions between electrons and ions has been derived.

scholarly journals Modification of transfer-matrix method for electromagnetic waves in layered superconductor in presence of dc magnetic field

2019 ◽  
Keyword(s):  
Magnetic Field ◽  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Electromagnetic Waves ◽  
Variable Parameter ◽  
Layered Superconductor ◽  
Legendre Functions ◽  
Magnetic Vortices ◽  
Dc Magnetic Field

In the present paper, we modify the transfer-matrix method to study the dissipation-free transition of electromagnetic waves of terahertz range through a plate of layered superconductor embedded in the dielectric environment in the presence of external direct current (dc) magnetic field. In this work, we сonsider TM-polarized electromagnetic waves. The setup is arranged in such a way that the dielectric and superconducting layers in the plate are perpendicular to its interface, and the external magnetic field is directed along the plate and parallel to the layers. We consider the case of a weak external dc field at which magnetic vortices do not penetrate the plate. Due to the nonlinearity of the Josephson plasma formed in the layered superconductor, the dc magnetic field penetrates non-uniformly into the plate and affects the electromagnetic wave. Hence, the magnitude of the external dc magnetic field can be used as a variable parameter to tune various phenomena associated with the propagation of an electromagnetic waves in layered superconductors. In the presence of the external homogeneous dc magnetic field, linear electromagnetic waves in the layered superconductor turn out to be non-exponential. Therefore we cannot directly apply the transfer matrix method, in which the amplitudes of the corresponding exponents are compared. However, in the present paper, it is shown that for a sufficiently thick plate, the matrices describing the wave transfer through the plate can be introduced. The analytical expressions for these matrices are derived explicitly in terms of special Legendre functions. The obtained transfer-matrices can be used for the further study of the wave transfer through the layered superconductor in the presence of an external dc magnetic field.

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