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1.
We report the first observation of “quasi-Planck” spectra of capillary turbulence on the surface of liquid hydrogen in the
dissipation domain. Capillary waves have been driven by low-frequency random force. We have observed that the frequency spectrum
of surface elevation changes its dependence from power-like 〈|ηω2|〉 ∼ ω−2,8 at middle-frequency domain to “quasi-Planck” distribution ∼e
ω/ω
d
at higher frequencies. The frequency ω
d
is proportional to the boundary frequency between inertial interval and dissipation domain and it is scaled up with the increase
of driving force. 相似文献
2.
Dielectric relaxation measurements of formamide (FMD)-N,N-dimethylaminoethanol (DMAE) solvent mixtures have been carried out over the entire concentration range using time domain
reflectometry technique at 25, 35 and 45°C in the frequency range of 10 MHz to 20 GHz. The mixtures exhibit a principle dispersion
of the Davidson-Cole relaxation type at microwave frequencies. Bilinear calibration method is used to obtain complex permittivity
ɛ*(ω) from complex reflection coefficient ρ*(ω) over the frequency range of 10 MHz to 10 GHz. The excess permittivity (ɛ
E), excess inverse relaxation time (1/τ)E, Kirkwood correlation factor (g
eff), activation energy and Bruggeman factor (f
B) are also calculated to study the solute-solvent interaction.
相似文献
3.
We study the effect of fluctuations on the ac conductivity of a layered superconductor for c-axis electromagnetic wave polarization. The fluctuation contributions of different physical nature and sign (paraconductivity,
Maki-Thompson anomalous contribution, one-electron density-of-states renormalization) are found to be suppressed by the external
field at different characteristic frequencies (ω
AL∼T-T
c
, ω
MT∼max{T-T
c
,τ
ϕ
−1
}, ω
DOS∼min{T, τ
−1}). As a result, the appearance of a nonmonotonic frequency dependence (pseudogap) in the infrared optical conductivity of
high-temperature superconductor is predicted.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 397–401 (25 September 1996)
Department of Theoretical Physics Moscow Institute of Steel and Alloys.
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
4.
C. X. Ren G. L. Chen J. M. Chen Y. J. Li J. Yang J. H. Zhang Y. X. Chen Z. X. Chen L. Wang S. C. Zou 《Applied Physics A: Materials Science & Processing》1992,54(3):303-307
In situ epitaxially grown YBa2Cu3O7– (YBCO) thin films on (100)SrTiO3 substrates with high critical current J
c=3.4 × 106 A/cm2 (at 77 K) and low microwave surface resistance R
s37 m (at 77 K, 50.9 GHz) are fabricated by dc magnetron sputtering using a large partially melted sintered planar target. A comparatively large homogeneous composition region can be obtained. The X-ray diffraction, X-ray double crystal diffraction, and high resolution transmission electron microscopy (HRTEM) analyses show that our deposited YBCO thin films are single crystalline containing mosaic blocks. The influence of substrate quality on the orientation behaviour of the films is also discussed. A method to improve the surface quality of the SrTiO3 substrate, which improves the properties of the thin film, is presented. 相似文献
5.
Summary Superconducting films of YBa2Cu3O7−x were depositedin situ on LaAlO3 substrates using single-target 90° off-axis sputtering. The obtained films have tipicalT
c values of 91K. Surface resistance measurements on as-grown films reach 1.1 mΩ at 77K and 10GHz; whilst on ion-etched patterned
resonant linesR
s (77K, 10GHz) it is about 10mΩ.
Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994. 相似文献
6.
S. V. Demishev A. V. Semeno N. E. Sluchanko N. A. Samarin J. Singleton A. Ardavan S. J. Blundell W. Hayes S. Kunii 《JETP Letters》1996,64(10):760-766
In undoped pure single crystals of the mixed valence compound SmB6 anomalous ESR absorption is observed in the frequency range v=40–120 GHz at temperatures of 1.8–4.2 K. The ESR for the case of the coherent ground state consists of two components corresponding
to g-factors g
1=1.907±0.003 and g
2=1.890±0.003. The amplitude of both ESR lines strongly depends on temperature in the temperature range studied: the amplitude
of the first line with g=g
1 increases and the amplitude of the second line decreases with temperature. A model based on consideration of intrinsic defects
in the SmB6 crystalline lattice, with a densit ∼1015−1016 cm−3, is suggested as an explanation for the anomalous ESR-behavior. In the frequency range v>70 GHz at T=4.2 K, in addition to the main ESR lines, a new magnetic resonance with a hysteretic field dependence is discovered.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 10, 707–712 (25 November 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
7.
C. Monthus T. Garel 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(1):39-45
The directed polymer in a 1+3 dimensional
random medium is known to present a disorder-induced phase
transition. For a polymer of length L, the high temperature
phase is characterized by a diffusive behavior for the end-point
displacement R2 ∼L and by free-energy fluctuations of order
ΔF(L) ∼O(1). The low-temperature phase is characterized by
an anomalous wandering exponent R2/L ∼Lω and
by free-energy fluctuations of order ΔF(L) ∼Lω
where ω∼0.18. In this paper, we first study the scaling
behavior of various properties to localize the critical temperature
Tc. Our results concerning R2/L and ΔF(L) point towards
0.76 < Tc ≤T2=0.79, so our conclusion is that Tc is equal
or very close to the upper bound T2 derived by Derrida and
coworkers (T2 corresponds to the temperature above which the ratio
remains finite as L ↦
∞). We then present histograms for the free-energy, energy and
entropy over disorder samples. For T ≫Tc, the free-energy
distribution is found to be Gaussian. For T ≪Tc, the free-energy
distribution coincides with the ground state energy distribution, in
agreement with the zero-temperature fixed point picture. Moreover the
entropy fluctuations are of order ΔS ∼L1/2 and follow a
Gaussian distribution, in agreement with the droplet predictions,
where the free-energy term ΔF ∼Lω is a near
cancellation of energy and entropy contributions of order L1/2. 相似文献
8.
K.C. Chung C.S. Wang A.J. Santiago J.W. Zhang 《The European Physical Journal A - Hadrons and Nuclei》2001,12(2):161-167
The parameters of the σ-ω-ρ model in the relativistic mean-field theory with nonlinear σ-meson self-interaction are determined
by nuclear-matter properties, which are taken as those extracted by fits to data based on nonrelativistic nuclear models.
The values of the relevant parameters are C
σ
2∼ 94, C
ω
2∼ 32, C
ρ
2∼ 26, b∼ - 0.09, c∼ 1, and the σ-meson mass m
σ∼ 370 MeV, while the value of the calculated nuclear- surface thickness is t∼ 1.4 fm. The field system is shown to be stable, since the σ-meson self-interaction energy is a lower bound in this whole
parameter region with positive c. On the other hand, the effective nucleon mass M* is larger than 0.73M, if the symmetry incompressibility Ks is assumed to be negative and the nuclear-matter incompressibility K0 is kept less than 300 MeV.
Received: 27 June 2001 / Accepted: 5 October 2001 相似文献
9.
A new mechanism of a “Coulomb explosion,” where ions are accelerated by the electric field separating charges at the magnetic
Debye radius r
B∼B/4πen
e, is proposed on the basis of a nonquasineutral model of electronic vortices in a magnetic field. It is shown by means of
numerical calculations that in the process of acceleration of the ions a collisionless shock wave, whose front has an effective
width of the order of δ∼r
B, determined by the breakdown of quasineutrality, is formed in a time of the order of ω
pi
−1
, where ωpi is the ion plasma frequency. The origin of such explosive dynamics is the formation of “holes” in the electron density at
characteristic times of the order of ω
pe
−1
(ωpe is the electronic plasma frequency) as a result of the generation of electronic vorticity by the Weibel instability of an
electromagnetic wave. Calculations for a laser pulse with intensity J∼6×1018 W/cm2 show that the ions expand in the radial direction with velocities up to 3.5×108 cm/s.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 669–674 (25 November 1999) 相似文献
10.
A magnetized, low-β plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton
and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼1011 cm−3, ∼4 × 1010 cm −3 and ∼2 × 1010 cm −3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive
to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations (ω < ω
ci) are observed and identified as flute modes. Here ω
ci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the
fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute
modes to understand the relevance of some of our experimental observations. 相似文献
11.
12.
A microscopic theory of the Efetov supermatrix sigma-model type is constructed for the low-lying electron states in a mixed
superconductive-normal system with disorder. This technique is used for the study of the localized states in the core of a
vortex in a moderately clean superconductor with τ
−1≫ω
0∼Δ2/E
F
. At low energies ε≪ω
Th∼ (ω
0/τ)1/2, the energy level statistics is described by the “zero-dimensional” limit of this supermatrix theory, and the result for
the density of states is equivalent to that obtained within Altland-Zirnbauer random matrix model. Nonzero modes of the sigma
model increase the mean interlevel distance by the relative amount [2 ln (1/ω
0
τ)]−1.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 78–83 (10 July 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
13.
B. Lalevic N. Fuschillo B. Kuliyev W. Wang 《Applied Physics A: Materials Science & Processing》1974,5(2):127-132
Transport and dielectric properties of polycrystalline CoO films were studied as functions of the applied field, frequency
and temperature. TheI–V plots showed that the Poole-Frenkel field emission mechanism is responsible for conduction at fields>105 V/cm. The ac conductivity σ(ω), the imaginary part of the dielectric constantε
2, and tan δ plots as functions of frequency revealed three dispersion regions. The σ(ω) andε
2 frequency dependence indicates a non-adiabatic hopping of charge carriers at low frequencies and adiabatic hopping at high
frequencies. The activation energy of a dielectric oscillator is 0.15 eV.
Work supported by the Office of Naval Research. 相似文献
14.
We investigate the electromagnetic response of a composite structure consisting of two diluted Drude metal layers with sub-wavelength
spacing at microwave frequencies. Simulations show that our structure can be considered as two equivalent thin films with
different permittivity layered together so as to effectively tune the transmission T(ω) and reflection R(ω) in a frequency band. We demonstrate a wide band between 5.98 GHz to 8.15 GHz where T(ω) and R(ω) are tuned within 50% ± 2%. Parametric explorations show that the working band can be further shifted by geometric scaling.
Our structure has potential to construct a metamaterial-based beam splitter which can be applied in a microwave or even terahertz
system. 相似文献
15.
Triglycine sulfate (TGS) films have been prepared by evaporation from a saturated aqueous solution on substrates of fused
quartz coated by a layer of thermally deposited aluminum (Al/SiO2) and white sapphire (α-Al2O3) on whose surface interdigital electrodes have been deposited by photolithography. The TGS films have a polycrystalline structure
made up of blocks measuring 0.1–0.3 mm (Al/SiO2) and 0.1 × 1.0 mm (α-Al2O3). The polar axis in the blocks is mostly confined to the substrate plane. The temperature dependences of the capacitance
and dielectric losses normal to and in the film plane have maxima at the temperature coinciding with that of the ferroelectric
phase transition in a bulk crystal, T
c
. The low-frequency conductivity G in TGS/Al/SiO2 structures displays a frequency dispersion described by the relation G ∼ ω
s
(s ≈ 0.82). The conduction can be tentatively ascribed to the hopping mechanism involving localized carriers with a ground state
energy of 0.8–0.9 eV. At temperatures above and below T
c
, the low-frequency conductivity in TGS/α-Al2O3 films operates through a thermally-activated mechanism with an activation energy of 0.9–1.0 eV. At the phase transition,
an additional contribution to conductivity appears in TGS/α-Al2O3 films with a dispersion G ∼ ω0.5, which can be associated with domain-wall relaxation. 相似文献
16.
Mehdi Ranjbar Azam Iraji zad Seyyed Mohammad Mahdavi 《Applied Physics A: Materials Science & Processing》2008,92(3):627-634
In this study WO
x
films were deposited by laser ablation of ultra-pure (5N) tungsten trioxide targets onto SiO2 or silicon substrates at 250°C temperature, 100 mTorr oxygen partial pressure and 1×10−5 Torr vacuum. Surface chemical states and compositions of the deposits were determined by X-ray photoelectron spectroscopy.
The results showed that deposits in oxygen partial pressure contain W6+ with x∼3.1, while vacuum-deposited films have different W states with various percentage distributions as W4+>W5+>W6+>W0, and x∼1. We used fast electrical resistance measurement as a probe to study the deposition process. Film resistance as a function
of deposition time in vacuum revealed some microsecond fluctuations modulated on the time variation curve of electrical resistance.
We attribute these data to surface absorption and desorption of oxygen during layer deposition. Finally, the effect of the
laser beam on the target’s structure, surface morphology and chemical state was studied. Our results revealed that in spite
of structural variation by laser irradiation, the O/W ratio remained about 3. 相似文献
17.
Y. B. Kale A. Ray R. D’Souza Q. V. Lawande B. N. Jagatap 《Applied physics. B, Lasers and optics》2010,100(3):505-514
We here present a comparative study of frequency stabilities of pump and probe lasers coupled at a frequency offset generated
by coherent photon-atom interaction. Pump-probe spectroscopy of the Λ configuration in D2 transition of cesium is carried out to obtain sub-natural (∼2 MHz) electromagnetically induced transparency (EIT) and sub-Doppler
(∼10 MHz) Autler-Townes (AT) resonance. The pump laser is locked on the saturated absorption spectrum (SAS, ∼13 MHz) and the
probe laser is successively stabilized on EIT and AT signals. Frequency stabilities of pump and probe lasers are calculated
in terms of Allan variance σ(2,τ) by using the frequency noise power spectrum. It is found that the frequency stability of the probe stabilized on EIT is
superior (σ∼2×10−13) to that of SAS locked pump laser (σ∼10−12), whereas the performance of the AT stabilized laser is inferior (σ∼6×10−12). This contrasting behavior is discussed in terms of the theme of conventional master-slave offset locking scheme and the
mechanisms underlying the EIT and sub-Doppler AT resonances in a Doppler broadened atomic medium. 相似文献
18.
A. A. Zhukov M. R. Trunin A. T. Sokolov N. N. Kolesnikov 《Journal of Experimental and Theoretical Physics》1997,85(6):1211-1217
The real part R
s and the imaginary part X
s of the surface impedance Z
s=R
s+ iX
s of Tl2Ba2CaCu2O8−δ
and YBa2Cu3O6.95 single crystals have been measured with high precision at frequency ω/2π=9.4 GHz in the temperature range 0<T<140 K. In the Tl2Ba2CaCu2O8−δ
crystal a linear temperature dependence R
s(T) has been found for T⩽50 K, and the magnetic field penetration depth λ(4.2 K)=X
s(4.2 K)/ω μ
0≈3760 Å has been measured. Along with well known features of the function Z
s(T) in high-quality YBa2Cu3O6.95 single crystals, such as the linearity of λ(T) and R
s(T) for T<T
c/3 and a maximum of R
s(T) at T∼T
c/2, the linearity range of λ(T) extends to T≃50 K, and this curve has a plateau in the range 60<T<85 K. The curve of R
s(T) in both the superconducting and normal states of YBa2Cu3O6.95 is well described by a two-fluid model with the electron-phonon mechanism of quasiparticle relaxation. A formula describing
the curve of λ
2(0)/λ
2(T) throughout the studied temperature range is also given.
Zh. éksp. Teor. Fiz. 112, 2210–2222 (December 1997) 相似文献
19.
R. K. Tiwari Farook Rahaman Saibal Ray 《International Journal of Theoretical Physics》2010,49(10):2348-2357
A five dimensional Kaluza-Klein space-time is considered in the presence of a perfect fluid source with variable G and Λ.
An expanding universe is found by using a relation between the metric potential and an equation of state. The gravitational
constant is found to decrease with time as G∼t
−(1−ω) whereas the variation for the cosmological constant follows as Λ∼t
−2, L ~ ([(R)\dot]/R)2\Lambda \sim (\dot{R}/R)^{2} and L ~ [(R)\ddot]/R\Lambda \sim \ddot{R}/R where ω is the equation of state parameter and R is the scale factor. 相似文献
20.
S. V. Demishev A. V. Semeno N. E. Sluchanko N. A. Samarin I. B. Voskoboinikov M. V. Kartsovnik A. E. Kovalev N. D. Kushch 《Journal of Experimental and Theoretical Physics》1997,84(3):540-544
Resonant microwave absorption in a (BEDO-TTF)2ReO4(H2O) organic conductor single crystal at a temperature of 1.9 K, a magnetic field of up to 70 kOe, and in the frequency band
between 30 and 120 GHz has been studied. A spectral component due to the cyclotron resonance (CR) of two-dimensional charge
carriers has been identified for ν⩾80 GHz and H⩾10 kOe. The effective mass m(ω) increases with the frequency from m≈0.8m
0 at ν=80 GHz to m≈0.95m
0 at ν=120 GHz. Measurements of the CR line position and FWHM as functions of frequency yield an independently determined imaginary
part of the memory function M(ω), which controls the dynamic magnetoconductivity, and the relaxation time τ(ν=100 GHz)≈2.9×10−11 s, which is more than thirty times the value of this parameter in the low-frequency limit τ(ν→0). The anomalous behavior of the CR line position and FWHM is caused by the dispersion of both real and imaginary parts
of M(ω), which are probably due to strong Fermi-liquid effects.
Zh. éksp. Teor. Fiz. 111, 979–987 (March 1997) 相似文献