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31.
R. Mélin S. Peysson 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(1):169-176
A Bethe-Peierls treatment to dilution in frustrated magnets and spin liquids is given. A spin glass phase is present at low
temperatures and close to the percolation point as soon as frustration takes a finite value in the dilute magnet model; the
spin glass phase is reentrant inside the ferromagnetic phase. An extension of the model is given, in which the spin glass/ferromagnet
phase boundary is shown not to reenter inside the ferromagnetic phase asymptotically close to the tricritical point whereas
it has a turning point at lower temperatures. We conjecture similar phase diagrams to exist in finite dimensional models not
constraint by a Nishimori's line. We increase frustration to study the effect of dilution in a spin liquid state. This provides
a “minimal” ordering by disorder from an Ising paramagnet to an Ising spin glass.
Received 9 April 1999 and Received in final form 27 September 1999 相似文献
32.
A programme is developed to calculate the polarizations of the radiation emitted after electron impact excitation. The fully relativistic distorted-wave method is used in cross-section calculations. The programme is applied to He- and Li-like ions. The calculated values of line polarization are compared with other theoretical results and experimental values. For He-like U, at lower incident energy, the present polarization agrees with the other theoretical ones within 1%, while at higher energy, the differences increase up to about 10%. For He-like Fe and Ti, the present results of polarization degree for most of the lines agree with the experimental data within the experimental error bars. For the Li-like Ti line q (ls2s2p^2p3/2 to ls^22s), the present value of the polarization agree excellently with another theoretical one, and both the values are consistent with the measured data within the experimental error bar. 相似文献
33.
Left-Handed Properties in Two-Dimensional Photonic Crystals Formed by Holographic Lithography 下载免费PDF全文
We give an analysis of the frequency distribution trends in the four lowest bands of two-dimensional square lattices formed by holographic lithography (HL) and in the lattices of the same kind but with regular dielectric columns with increasing filling ratios, and then present a comparative study on the left-handed properties in these two kinds of structures using plane wave expansion method and finite-difference time-domain (FDTD) simulations. The results show that the left-handed properties are more likely to exist in structures with large high-epsilon filling ratios or in a connected lattice. 相似文献
34.
M. Xu A. Vantomme D. Smeets K. Vanormelingen S.D. Yao 《Journal of Crystal Growth》2009,311(16):4007-4010
Applying both template and Si cap technology, we achieved the epitaxial growth of CoSi2 directly on Si(1 0 0) substrate by rapid thermal annealing (RTA). The crystal quality of CoSi2 film is found to be significantly dependent on the Si cap thickness. In our work, a good-quality CoSi2 film with a minimum of χmin~11.6% and 3.3 Ω/square was obtained as a 15 nm Co with a subsequent 15 nm Si cap layer is deposited on an oxide-mediated CoSi2 template and followed by an anneal at 1050 °C under N2 protection; whereas too thin or thick Si cap layer will deteriorate the crystalline quality of CoSi2. These experimental results are discussed in combination with the simulation of Rutherford backscattering spectroscopy and X-ray reflectivity. 相似文献
35.
C. Vrejoiu S. Zota N. Mezincescu M. Boca 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(4):503-513
The non-relativistic matrix elements and cross-sections of the radiative recombination for H-like atoms are calculated by
considering the retardation corrections up to the first order in . These corrections are evaluated for the transitions to the spherical states using recursion relations which lead to fast
and accurate calculations of the cross-sections.
Received 4 June 1999 相似文献
36.
Chen Guo-xin P.P. Ong 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):153-156
Relativistic distorted-wave method was used to calculate the electron impact excitation collision strengths for transitions
2
s2
1
S0-2
s
2
p
3
P1 of Be-like isoelectronic ions. The target states were described, respectively, by 10-level, 46-level and 133-level MCDF configuration-expansion.
The relativistic continuum orbitals were calculated in the potential field of frozen target-ion charge distribution with semi-classical
exchange potential. The influence of the target states on this collision process along the isoelectronic sequence was investigated
in the above three MCDF configuration-expansion modes. It was found that the configurations in the n
=3 and the n
=4 complexes have great influence on both the high and the low Z ions but the influence is relatively small for intermediate Z ions. The latter phenomenon was attributed to competition between opposing correlation and relativistic effects on the collision
strengths.
Received: 25 February 1998 / Received in final form: 18 June 1998 相似文献
37.
We present the development of a holographic interferometer that uses a photorefractive crystal of the sillenite family as
holographic recording medium. The aim of this work is to achieve a transportable and breadboard instrument, with a flexible
design and which is user friendly for the quantified measurements of displacements on large scattering objects. The state
of the art of the use of photorefractive crystals in holographic interferometry is presented. Based on the latter, a method
that is the best suited to our mentioned objectives is chosen: the real-time interferometric technique associated with the
crystal configuration exhibiting diffraction anisotropy. On this basis, we have studied and compared two imaging systems,
we have experimentally determined the holographic figures of merit of three sillenite crystals samples, and, finally, we have
shown the use of two measurement quantification methods. The result of these investigations is a certified and transportable
holographic camera prototype containing all the necessary equipment for its operation, which can be easily adapted to various
applications. Among these, we show its use in the detection of defects in composite structures, in the measurement of time-evolving
deformations, and in the measurement of vibration modes.
Received: 4 December 1998 / Revised version: 6 March 1999 / Published online: 12 April 1999 相似文献
38.
D.Z. Anderson V. Damiao D. Popovic Z. Popovic S. Romisch A. Sullivan 《Applied physics. B, Lasers and optics》2001,72(6):743-748
Suppression of an optical carrier from an RF modulated laser beam of wavelength 532 nm is performed using two-beam coupling
in photorefractive barium titanate. A theoretical analysis reveals that perfect suppression can be achieved at a specific
modulation strength, which depends on the gain and intensity ratio between the two beams. The experiments achieve a maximum
of -72.9±2.4 dB carrier suppression at the theoretically ideal modulation strength, and -61.0±2.4 dB for small modulation
strengths.
Received: 29 November 2000 / Revised version: 2 February 2001 / Published online: 27 April 2001 相似文献
39.
H. Wang F.J. Yang Q. Mo J. Zhang H.B. Wang Y. Wang 《Journal of magnetism and magnetic materials》2009,321(17):2627-2629
FePt multilayer composite films with and without B4C interlayer have been prepared by magnetron sputtering, respectively, and subsequent annealing in vacuum. It was found that the B4C layers effectively serve as spacers to separate the FePt layers, enhancing (0 0 1) orientation of FePt alloy. Our results show that highly (0 0 1) oriented FePt/B4C films have significant potential as perpendicular recording media. 相似文献
40.
Arrays of elliptical particles with aspect ratio 1:3 and short axes 50, 100 and 150 nm were prepared by electron-beam lithography and ion-beam milling of epitaxial (0 0 1)Fe films of thicknesses 10 and 20 nm. The domain state of an individual particle imaged by magnetic force microscopy in zero field after demagnetization was observed to change from being bi-domain or multidomain (MD) to stable single domains (SD) as the lateral size and film thickness were decreased. The critical size for SD formation was found to be close to the actual lateral sizes of 100 nm×300 nm and 150 nm×450 nm for the thicknesses of 20 and 10 nm, respectively. Only in the 10 nm thick ellipses of lateral size 100 nm×300 nm, the magnetization reversal may take place through coherent rotation. For all other investigated samples, the experimental switching field is lower than what would be required for this process. 相似文献