Dielectric measurements in the submillimeter wavelength region

Волков, А. А.; Goncharov, Yu. G.; Kozlov, G. V.; Лебедев, С. П.; Prokhorov, A M

doi:10.1016/0020-0891(85)90109-5

Cited by 252 publications

(109 citation statements)

References 4 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…Therefore the features of experimental observation of AFER in these compounds are close to those at THz frequencies [15] or optics [75,76]. If the dimensions of the sample are comparable with or smaller than the wavelength of the ac electric field, then the results above is directly applicable.…”

Section: Afer In α-mentioning

confidence: 66%

“…In this frequency region the contribution of magnetic permeability ( ) μ ω to ( ) n ω in most cases is negligible and frequently ( ) 1 μ ω ≈ is assumed. The transmittance experiments at THz frequencies can be carried out in a MachZehnder interferometer arrangement [15] which allows measurements of amplitude and phase shift in a geometry with controlled polarization of the radiation. The absolute values of the complex dielectric permittivity ε = ε 1 + iε 2 are determined directly from the measured spectra using the Fresnel optical formulas for transmittance T = |t| 2 of a plane-parallel sample:…”

Section: Methods Samples and Ferroelectricitymentioning

confidence: 99%

See 1 more Smart Citation

Electrically active magnetic excitations in antiferromagnets (Review Article)

Krivoruchko

2012

Low Temperature Physics

View full text Add to dashboard Cite

The magnetic resonance operation by electric field is highly nontrivial but the most demanding function in the future spin-electronics. Recently observed in a variety of multiferroics materials named the collective electrically active magnetic excitations, frequently referred to as "electromagnons", reveal a possible way to implement such a function. Experimental advances in terahertz spectroscopy of electromagnons in multiferroics as well as related theoretical models are reviewed. The earlier theoretical works, where the existence of electric-dipole active magnetic excitations in antiferro-and ferrimagnets with collinear spin structure has been predicted, are also discussed. Multi-sublattice magnets with electrically active magnetic excitations at room temperature give a direct possibility to transform one type of excitation into another in a terahertz time-domain. This is of crucial importance for the magnon-based spintronics as only the short-wavelength exchange magnons allow the signal processing on the nanoscale distance.

show abstract

Section: Afer In α-mentioning

confidence: 66%

Section: Methods Samples and Ferroelectricitymentioning

confidence: 99%

Electrically active magnetic excitations in antiferromagnets (Review Article)

Krivoruchko

2012

Low Temperature Physics

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…Three types of experiments were performed: (a) polarized reflection measurements using a Fourier transform spectrometer in the frequency range between 12 and 1000 cm −1 , and the temperature range from 4 to 300K; in-situ evaporated gold films were used as a reference; (b) polarized transmission measurements in the frequency range from 4 to 20 cm −1 using a Mach-Zehnder interferometer arrangement [11], which allows measurements of both transmission and phase shift (from the Fresnel formu- lae, the absolute values of the complex dielectric function can be determined directly from the measurements); and (c) microwave cavity perturbation measurements at 1, 25 and 39 GHz. For (a), the dimensions of the sample were 0.7mm×5mm×6mm for the a, b and c directions respectively.…”

mentioning

confidence: 99%

Observation of the Transverse Optical Plasmon inSmLa0.8Sr0.2CuO4−δ
Dulić
¹
,
Pimenov
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
47
5
45
0
View full text Add to dashboard Cite

We present microwave and infrared measurements on SmLa0.8Sr0.2CuO 4−δ , which are direct evidence for the existence of a transverse optical plasma mode, observed as a peak in the c-axis optical conductivity. This mode appears as a consequence of the existence of two different intrinsic Josephson couplings between the CuO2 layers, one with a Sm2O2 block layer, and the other one with a (La,Sr)2O 2−δ block layer. From the frequencies and the intensities of the collective modes we determine the value of the compressibility of the two dimensional electron fluid in the copper oxygen planes. 74.25.Gz In 1966 A.J. Leggett predicted for superconductors with two bands of charge carriers a collective oscillation corresponding to small fluctuations of the relative phases of the two condensates, briefly indicated as excitons below the superconducting gap [1]. In principle these excitons should be observable with electromagnetic radiation, but in practice the effect on the infrared optical properties of most superconducting materials has been too small to be observable, except for, as we will demonstrate in the present paper, the bi-layer cuprate superconductors. The cuprate high temperature superconductors naturally form weakly coupled stacks of superconducting layers [2]. Some members of this family, e.g. Bi 2 Sr 2 CaCu 2 O 8 , have two superconducting layers per unit cell. These materials are realizations of a two-band superconductor, satisfying the following unique conditions: (i) For polarization of the electric field perpendicular to the conducting planes the metallic screening is very weak due to strong anisotropy of the static and dynamical electrical conductivity. (ii) The dipole selection rules allow optical transitions which resonate at the Josephson exciton energy.In Ref.[3] two of us (DvdM and AAT) calculated the dielectric function for cuprate superconductors with two CuO 2 planes per unit cell, using the Lawrence-Doniach model [2] with alternating coupling constants (the 'multilayer model'). A direct consequence was the presence of a transverse optical plasma mode, polarized perpendicular to the planes for propagation along the planes. Similar to a transverse optical phonon, and in contrast to the transverse Josephson plasma resonance (JPR) in single layer cuprates, this mode is observable as an optically allowed absorption in measurements of the optical conductivity. In Fig. 1 close proximity to the optical phonons it was not possible to separate these electronic collective modes from the optical lattice vibrations [5], which complicates the quantitative analysis of this interesting phenomenon.Both in the two-band exciton model and in the multilayer model the collective modes are oscillations of the relative phase of the two condensates, the inertia of which is due to the finite Josephson coupling between the two condensates. In Ref.[1] the restoring force was provided by the fact, that if δN electrons are added to a plane, the free energy increases with an amount δF = µδN + δN 2 /(2Kn 2 ). Here µ, K, and ...

show abstract

“…Such variations in the microwave or millimeter range of electromagnetic wave spectrum are associated completely with magnetic permeability. The mathematical relationships between transmittance and reflectance spectra, and refractive and absorption indexes are presented that 11,15 …”

Section: Resultsmentioning

confidence: 99%

Tunable ferromagnetic resonance in La-Co substituted barium hexaferrites at millimeter wave frequencies

Korolev

Zhong

et al. 2018

AIP Advances

View full text Add to dashboard Cite

Transmittance measurements have been performed on La-Co substituted barium hexaferrites in millimeter waves. Broadband millimeter-wave measurements have been carried out using the free space quasi-optical spectrometer, equipped with a set of high power backward wave oscillators covering the frequency range of 30 – 120 GHz. Strong absorption zones have been observed in the millimeter-wave transmittance spectra of all La-Co substituted barium hexaferrites due to the ferromagnetic resonance. Linear shift of ferromagnetic resonance frequency as functions of La-Co substitutions have been found. Real and imaginary parts of dielectric permittivity of La-Co substituted barium hexaferrites have been calculated using the analysis of recorded high precision transmittance spectra. Frequency dependences of magnetic permeability of La-Co substituted barium hexaferrites, as well as saturation magnetization and anisotropy field have been determined based on Schlömann’s theory for partially magnetized ferrites. La-Co substituted barium hexaferrites have been further investigated by DC magnetization to assess magnetic behavior and compare with millimeter wave data. Consistency of saturation magnetization determined independently by both millimeter wave absorption and DC magnetization have been found for all La-Co substituted barium hexaferrites. These materials seem to be quite promising as tunable millimeter wave absorbers, filters, circulators, based on the adjusting of their substitution parameters.

show abstract

Dielectric measurements in the submillimeter wavelength region

Cited by 252 publications

References 4 publications

Electrically active magnetic excitations in antiferromagnets (Review Article)

Electrically active magnetic excitations in antiferromagnets (Review Article)

Observation of the Transverse Optical Plasmon inSmLa0.8Sr0.2CuO4−δ
Dulić
¹
,
Pimenov
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
47
5
45
0
View full text Add to dashboard Cite

Tunable ferromagnetic resonance in La-Co substituted barium hexaferrites at millimeter wave frequencies

Contact Info

Product

Resources

About

Dielectric measurements in the submillimeter wavelength region

Cited by 252 publications

References 4 publications

Electrically active magnetic excitations in antiferromagnets (Review Article)

Electrically active magnetic excitations in antiferromagnets (Review Article)

Observation of the Transverse Optical Plasmon inSmLa0.8Sr0.2CuO4−δDulić1, Pimenov2, Marel3 et al. 2001Phys. Rev. Lett.475450View full textAdd to dashboardCite

Tunable ferromagnetic resonance in La-Co substituted barium hexaferrites at millimeter wave frequencies

Contact Info

Product

Resources

About

Observation of the Transverse Optical Plasmon inSmLa0.8Sr0.2CuO4−δ
Dulić
¹
,
Pimenov
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
47
5
45
0
View full text Add to dashboard Cite