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841.
J. T. Chayes L. Chayes Daniel S. Fisher T. Spencer 《Communications in Mathematical Physics》1989,120(3):501-523
Thed-dimensional, nearest-neighbor disordered Ising ferromagnet: $$H = - \sum {J_{ij} \sigma _i \sigma _j }$$ is studied as a function of both temperature,T, and a disorder parameter,λ, which measures the size of fluctuations of couplingsJ ij ≧0. A finite-size scaling correlation length,ζ f (T, λ), is defined in terms of the magnetic response of finite samples. This correlation length is shown to be equivalent, in the scaling sense, to the quenched average correlation lengthζ(T, λ), defined as the asymptotic decay rate of the quenched average two-point function. Furthermore, the magnetic response criterion which definesζ f is shown to have a scale-invariant property at the critical point. The above results enable us to prove that the quenched correlation length satisfies: $$C\left| {\log \xi (T)} \right|\xi (T) \geqq \left| {T - T_c } \right|^{ - {2 \mathord{\left/ {\vphantom {2 d}} \right. \kern-\nulldelimiterspace} d}}$$ which implies the boundv≧2/d for the quenched correlation length exponent. 相似文献
842.
843.
A parametric study of sandwich-type discharge chamber nitrogen lasers has been carried out. A non-monotonic dependence of the energy emitted by the laser and the discharge chamber thickness is found. Discharge chambers with = 1 have the best electro-optical efficiency. The ratio between the electrode gap,d, and is found to be a scaling parameter. The possible influence of wall ablation in the comportment is also discussed. 相似文献
844.
A. Barhdadi H. Amzil J. C. Muller P. Siffert 《Applied Physics A: Materials Science & Processing》1989,49(3):233-237
We have studied the influence of conventional and rapid thermal treatments at 850°C for 30 min and 10 s, respectively, on the recombination activity of the9,13 (P-type) and25 (N-type) grain boundaries in silicon. The analyses were made by scanning electron microscopy (SEM) working in the electron beam induced current mode (EBIC) and completed by minority carrier diffusion length measurements. The main result obtained from this study shows the importance of the rapid thermal process as a suitable thermal treatment for polycrystalline materials. 相似文献
845.
The dynamic susceptibility () measured between 10 Hz and 10 MHz on different GdCl3-ellipsoids (T
c=2.21 K) reveals a completely reversible motion of the domain walls. Taking into account the contribution of the fast adiabatic intradomain magnetization to the nearly Debye-shaped (), we determine for the first time the kinetic Onsager coefficientL
d of the domain wall relaxation of a ferromagnet. Approaching the CurietemperatureL
d speeds up critically, which by a novel simple relaxational model can be related to the increasing width (=correlation length) of linear Bulaevskii-Ginzburg domain-walls and to the shrinking domain period. The reduction ofL
d by an external field can be represented by a universal scaling function, and within the same dynamical model, this effect is ascribed to the increase of the domain period, predicted for a bubble phase. However, the effect of sample size onL
d is much smaller than expected. 相似文献
846.
J. Czerwonko 《Zeitschrift für Physik B Condensed Matter》1989,73(4):433-436
Following the idea by Ketterson, this author showed that in neutral and normal Fermi liquids, the polarization effects lead to coupling of transverse spin waves to zero sound at precessing magnetization of the system. The observable effects, at the range of dc fields applied to3He, can appear only if the zero sound is degenerate with transverse spin waves excited in the reference frame rotating with the Larmor frequency about theH
dc-axis. This possibility is investigated at Landau parameters vanishing atl>1 and nonzero, though small, coupling of the density to the spin density and the particle current to the spin current, resulting from the polarization of the system byH
dc. The degeneration is, in general, possible but, at large values of the zero sound velocity with respect to the Fermi velocity, caused by large values of the Landau parameterF
0
s
and alsoF
1
s
for3He, atF
0
a
–0.7, it appears only at positiveF
1
a
. All experimental estimations of this parameter agree in its negativity excluding the degeneration of the zero sound and transverse spin waves for3He. 相似文献
847.
Optically pumped laser emission has been observed on the NaK 2(A)1+ 1(X)1+ electronic state transition. The emission occurs between 1.015 and 1.035 m when a sodium-potassium heat-pipe oven is pumped with 695–745 nm pulsed dye laser radiation. The laser emission occurs on many ro-vibrational transitions without the use of cavity mirrors. However, the addition of a simple cavity increases both the number of observed lasing transitions and the amplitude of the emission on each line. We report our results for the dependence of the emission intensity on pump laser power, oven temperature, and buffer gas pressure. 相似文献
848.
J. Požela A. Namajūnas A. Tamaševičius J. Ulbikas 《Applied Physics A: Materials Science & Processing》1989,48(2):181-188
A method for quantitative characterization of chaotic dynamical systems is discussed. An electronic instrument for determining the number of independent variablesk
*, involved in the motion, is described. It allows one to obtain these in real time from a single observable. The suggested technique has been applied to quantification of strange attractors underlying chaotic instabilities in semi-insulating GaAsCr, and n-Ge, irradiated with high energy electrons. In n-Ge, for instance, the measured numbersk
* range from 2 to 4 depending on control parameters. These measurements reveal the highly deterministic nature of the observed chaotic oscillations. The physical mechanisms responsible for the current instabilities and chaotic behaviour are discussed. 相似文献
849.
M. Konuma H. Stutzler J. Kuhl E. Bauser 《Applied Physics A: Materials Science & Processing》1989,48(5):465-469
Chemical etching of single-crystal Si in an NF3 atmosphere is performed by continuous irradiation with an Ar+ laser at 514.5 nm. The etching process proves to be a thermally stimulated chemical reaction between solid Si and NF3 gas. The experimental results show how the depth and width of the etched grooves depend on laser power, scan speed, and gas pressure. The etch rates observed may exceed 25 m/s. 相似文献
850.
The interbranch scattering of X-rays at dislocations is studied experimentally and with the aid of numerical simulations. Narrow beam of a small divergence is used for the study which is made both in the Laue and Bragg case of diffraction. The role of interbranch scattering in the formation of defect contrast in X-ray topography is discussed. 相似文献