共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Hazareesing J.-P. Bouchaud 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):713-724
We reconsider the problem of the static thermal roughening of an elastic manifold at the critical dimension d=2 in a periodic potential, using a perturbative Functional Renormalization Group approach. Our aim is to describe the effective
potential seen by the manifold below the roughening temperature on large length scales. We obtain analytically a flow equation
for the potential and surface tension of the manifold, valid for low temperatures. On a length scale L, the renormalized potential is made up of a succession of quasi parabolic wells, matching onto one another in a singular
region of width for large L. For strong periodic potential, the perturbation theory breaks down, and we argue, based on a variational calculation, that
the transition becomes first order. We also obtain numerically the step energy as a function of temperature, and relate our
results to the existing experimental data on 4He. Finally, we examine the case of a non local elasticity which is realized physically for the contact line.
Received 16 April 1999 and Received in final form 11 October 1999 相似文献
2.
S. Ban X.X. Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):153-158
The interface polaron states in a heterojunction are discussed by considering an energy-band bending near the interface and
the influence of an image potential. The ground state energy and the effective mass of a polaron are variationally calculated.
The numerical results for the GaAs/
heterojunction are given. It is shown that even though the influences from bulk longitudinal optical (LO) phonons are more
important for the heterojunctions with lower Al composition, the contributions from two branches of interface optical (IO)
phonons are not negligible. For the heterojunctions with higher Al composition, both the influences from LO phonons and two
branches of IO phonons are important. The band-bending plays an important role for the interface localization of polarons,
but the influence of the image potential is not essential.
Received: 4 November 1997 / Revised and Accepted: 9 March 1998 相似文献
3.
J.F. Nagle S. Tristram-Nagle H. Takahashi I. Hatta 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):399-400
This comment shows that data recently reported [#!ref1!#] as being seemingly in conflict with earlier data [#!ref2!#] are,
in fact, in excellent agreement. Together, both studies confirm that the kinetics of the subgel phase transformation in dipalmitoylphosphatidylcholine
(DPPC) lipid bilayers obeys Kolmogorov-Avrami (K-A) theory [#!ref3!#,#!ref4!#] with an anomalously low effective dimensionality.
Received: 11 December 1997 / Accepted: 28 January 1998 相似文献
4.
G. Plunien T. Beier Gerhard Soff H. Persson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(2):177-185
We present a calculation scheme for the two-loop vacuum polarization correction of order to the Lamb shift of hydrogenlike high-Z atoms. The interaction with the external Coulomb field is taken into account to all orders in . By means of a modified potential approach the problem is reduced to the evaluation of effective one-loop vacuum polarization
potentials. An expression for the energy shift is deduced within the framework of partial wave decomposition performing appropriate
subtractions. Exact results for the two-loop vacuum polarization contribution to the Lamb shift of K- and L-shell electron
states in hydrogenlike Lead and Uranium are presented.
Received: 10 August 1997 / Revised: 31 October 1997 / Accepted: 18 November 1997 相似文献
5.
F.H.L. Eßler V.E. Korepin F.T. Latrémolière 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):559-563
We consider finite temperature dynamical correlation functions in the interacting delta-function Bose gas. In the low-temperature
limit the asymptotic behaviour of correlation functions can be determined from conformal field theory. In the present work
we determine the deviations from conformal behaviour at low temperatures.
Received: 14 January 1998 / Accepted: 17 March 1998 相似文献
6.
H. Kellay J. Rouch 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):121-129
In this paper we study the influence of the magneto-coupling effect between the longitudinal motion component and the transverse
Landau orbits of an electron on transmission features in single barrier structures. Within the parabolic conduction-band approach,
a modified one-dimensional effective-mass Schr?dinger equation, including the magneto-coupling effect generated from the position-dependent
effective mass of the electron, is strictly derived. Numerical calculations for single barrier structures show that the magneto-coupling
effect brings about a series of the important changes for the transmission probability, the above-barrier quasi-bound states,
and the tunneling time. Through examining the variation of the above-barrier resonant-transmission spectrum with the barrier
width and observing the well-defined Lorentzian line-shape of the above-barrier resonant peaks, we convincingly show that
the above-barrier resonant transmission in single barrier structures is delivered by the above-barrier quasibound states in
the barrier region, just as the below-barrier resonant tunneling in double barrier structures is mediated by the below-barrier
quasi-bound states in the well. Furthermore, we come to the conclusion that the magneto-coupling effect brings about not only
the splitting of the above-barrier quasi-bound levels but also the striking reduction of the level-width of the quasi-bound
states, correspondingly, the substantial increase of the density of the quasi-bound states. We suggest that magneto-coupling
effects may be observed by the measurements of the optical absorption spectrum associated with the above-barrier quasi-bound
states in the single barrier structures.
Received: 26 September 1997 / Revised: 26 November 1997 / Accepted: 15 December 1997 相似文献
7.
K. Skwarek A. Pȩkalski M. Ausloos 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(3):369-375
A method for estimating, via the Monte-Carlo simulation, the most often realized diffusion mechanisms in 2D ordered structures is presented. Taking as
an example the diffusion of oxygen ions in high temperature superconductor we propose several diffusion mechanisms and show to what extent they depend on the temperature
and concentration of the diffusing particles. Our results are compared with the ones proposed earlier on the basis of energy
arguments. We find also additional trajectories, different from those earlier reported in that system.
Received 9 November 1998 相似文献
8.
A. Goujon O. Roubeau F. Varret A. Dolbecq A. Bleuzen M. Verdaguer 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(1):115-124
We studied the photo-excitation process, the relaxation of the photo-excited state towards the stable state, and the photo-induced
magnetic properties of the Prussian blue analogue Rb0.52Co [Fe(CN)6]0.84, 2.3 H2O. Magnetic, M?ssbauer and reflectivity measurements have been performed during and after illumination. The efficiency of
the photo-excitation device is maximum at nm. The process, however, is severely hindered by bulk absorption of the light; it is rapidly completed at the surface of
the sample and then proceeds slowly in the bulk. Under the effect of photo-excitation the system turns from a dia- to a ferri-
magnet, with a value K, indicative of the transformation of the material due to the following optical electron transfer: Thermal relaxation towards the stable electronic state is observed in the 95-110 K temperature interval, obeying a self-accelerated
kinetics. At low temperature, a weak, non-exponential, relaxation is detected. These features are discussed in terms of co-operative
effects in the frontal process of photo- excitation. The peculiarities of a photo-excited state created below the magnetic
ordering temperature are discussed. A metastable magnetic state has been observed in low fields, denoted “Raw Photo-Induced
State" (RPI), with a magnetization curve in-between the field-cooled and zero-field-cooled curves.
Received 12 March 1999 and Received in final form 11 December 1999 相似文献
9.
G.P. Malik Raman K. Jha V.S. Varma 《The European Physical Journal A - Hadrons and Nuclei》1998,3(4):373-375
The study of meson formation in quark-gluon plasma using a temperature-dependent Bethe-Salpeter formalism presented earlier,
is now extended to a logarithmic and a combination of a Coulomb plus a square-root kernel. We are able to get good fits to
the meson masses with both kinds of kernels and our present results are qualitatively similar to those obtained for the Coulomb
plus a linear kernel.
Received: 9 February 1998 / Revised version: 27 April 1998 相似文献
10.
A. Kuhn S. Steuerwald K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):57-70
Coherent population transfer between vibrational levels of the NO molecule induced by the interaction of two delayed laser
pulses, also referred to as stimulated Raman scattering involving adiabatic passage (STIRAP), is studied experimentally in
a molecular beam and in the bulk. The consequences of hyperfine splitting and Doppler broadening are discussed in detail.
Unlike in previous studies of this kind, transfer occurs simultaneously between more than one group of non degenerate levels.
In a molecular beam or in the bulk, the transfer efficiency of STIRAP exceeds that obtained by Stimulated Emission Pumping
(SEP) by a factor of 3.6 or 15, respectively. We estimate the absolute transfer efficiency T in the beam to be , while is found in the bulk. In both cases, this is of the maximum value expected from numerical studies. Possible reasons for this discrepancy are discussed. Finally we show
that the absorption of a pump pulse in a weakly absorbing medium is significantly enhanced by the presence of a copropagating
Stokes pulse when the Rabi frequency of the latter is smaller than the width of the Doppler profile . The relation of this observation to the phenomenon of Electromagnetically Induced Transparency (EIT), which is observed
for , is also discussed.
Received: 11 September 1997 / Revised: 28 October 1997 / Accepted: 29 October 1997 相似文献
11.
Y.I. Latyshev B. Pannetier P. Monceau 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(4):421-426
We demonstrate for the first time that a periodic array of submicrometer holes (antidots) can be patterned into thin single
NbSe3 crystals. We report on the study of Charge Density Wave (CDW) transport of the network of mesoscopic units between antidots.
Size of the elementary unit can be as small as 0.5 μm along the chain axis and in cross-section. We observe size effects for Ohmic residual resistance and in CDW transport current-voltage characteristics
in submicronic networks.
Received: 25 November 1997 / Received in final form: 30 March 1998 / Accepted: 6 April 1998 相似文献
12.
M. Dressler F. Bassani G. Czajkowski 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(4):681-686
We show how to compute the optical functions (reflectivity, transmission, and absorption) of polydiacetylene chains diluted
in their monomer matrix exposed to a uniform electric field in the chain direction, in the excitonic energy region. Adopting
a model electron-hole potential, we derived an analytical expression for the effective chain susceptibility, which gives the
optical functions. The resulting absorption shows excitonic peaks below the gap and Franz-Keldysh oscillations above the gap.
The method has been applied for a 3BCMU polydiacetylene chain, showing a good agreement with experimental spectra.
Received 5 November 1998 and
Received in final form 23 February 1999 相似文献
13.
B. Ruzicka L. Degiorgi U. Ammerahl G. Dhalenne A. Revcolevschi 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(3):301-305
The optical reflectivity as a function of temperature of the title compound for x
=0, 5 and 12 has been measured over a broad spectral range from 4 meV up to 12 eV. Our findings suggest a very anisotropic dynamics
of the charge excitation spectrum when measuring along or perpendicular to the ladders. Moreover, a metal-insulator transition
develops at low temperatures, leading to a suppression of Drude spectral weight in the far and mid-infrared spectral range.
We identify this behaviour as a consequence of the localization effects for small Ca substitution, and of the possible formation
of a charge density wave condensate for large Ca substitution.
Received: 18 June 1998 /
Accepted: 17 July 1998 相似文献
14.
15.
K. Pomorski K. Dietrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):353-364
We investigate the existence of stable charged metallic bubbles using the shell correction method. We find that for a given
mesoscopic system of n atoms of a given metal and (positive) elementary charges, a metallic bubble turns out to have a lower total energy than a compact spherical cluster,
whenever the charge number q is larger than a critical charge number qc. For a magic number (n-q) of free electrons, the spherical metallic bubble may become stable against fission.
Received: 17 November 1997 / Revised: 28 May 1998 / Accepted: 20 July 1998 相似文献
16.
17.
G. Backenstoss J. Egger H. Koch H.P. Povel A. Schwitter L. Tauscher 《Nuclear Physics B》1974,73(2):189-201
Relative intensities of numerous kaonic X-ray transitions have been measured for the elements C,P,S, and C1, from which level widths due to the strong K-nucleus absorption have been determined. From these and earlier published data, optical potential parameters have been derived and possible consequences on the nuclear matter distribution are discussed. 相似文献
18.
T. Ouchterlony I.V. Zozoulenko C.-K. Wang K.-F. Berggren C. Gould A.S. Sachrajda 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(2):361-370
We study the conductance of a square quantum dot, modeling the potential with a self-consistent Thomas-Fermi approximation.
The resulting potential is characterized by level statistics indicative of mixed chaotic and regular electron dynamics within
the dot in spite of the regular geometry of the gates defining the dot. We calculate numerically, for the case of a quantum
dot with soft confinement, the weak localization (WL) correction. We demonstrate that this confining potential may generate
either Lorentzian or linear lineshapes depending on the number of modes in the leads. Finally, we present experimental WL
data for a lithographically square dot and compare the results with numerical calculations. We analyze the experimental results
and numerical simulations in terms of semiclassical and random matrix theory (RMT) predictions and discuss their limitations
as far as real experimental structures are concerned. Our results indicate that direct application of the above predictions
to distinguish between chaotic and regular dynamics in a particular cavity can not always lead to reliable conclusions as
the shape and magnitude of the WL correction can be strongly sensitive to the geometry-specific, non-universal features of
the system.
Received 13 May 1998 相似文献
19.
H. Narnhofer 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(3):351-356
It is shown using Vlasov dynamics that the density distribution corresponding to a mean field Bose condensate in an external
time dependent potential is adiabatically stable whereas density distributions corresponding to finite temperature are not.
Received: 27 February 1998 / Revised: 20 April 1998 / Accepted: 23 April 1998 相似文献
20.
M. Barthélémy H. Orland 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(4):537-541
In this article, we propose a new method to compute the effective properties of non-linear disordered media. We use the fact
that the effective constants can be defined through the minimum of an energy functional. We express this minimum in terms
of a path integral allowing us to use many-body techniques. We obtain the perturbation expansion of the effective constants
to second order in disorder, for any kind of non-linearity. We apply our method to the case of strong non-linearities (i.e.
, where is fluctuating from point to point), and to the case of weak non-linearity (i.e.
where and fluctuate from point to point). Our results are in agreement with previous ones, and could be easily extended to other types
of non-linear problems in disordered systems.
Received: 13 May 1998 / Accepted: 27 July 1998 相似文献