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1.
I. V. Golosovsky O. P. Smirnov R. G. Delaplane A. Wannberg Y. A. Kibalin A. A. Naberezhnov S. B. Vakhrushev 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):211-216
By neutron diffraction it was shown that nanostructured Se confined within a porous glass matrix exists in a
crystalline as well as in an amorphous state. The spontaneous crystallization of crystalline Se from confined amorphous
phase was observed. The root-mean-square amplitudes of the atomic motions in the bulk as well as in confinement are found
to be essentially different in a basal plane and in the perpendicular direction along the hexagonal axis. The atomic
motions in the confined Se differ from the atomic motions in the bulk at low temperatures. The results shows an unusual
“freezing" of the atomic motion along the chains, while the atomic motions in the perpendicular plane still keep. This
“freezing" is accompanied by the deformation of nanoparticles and the appearance of inner stresses. This effect is
attributed to the interaction of confined nanoparticle with the cavity walls. 相似文献
2.
G. Iadonisi F. Trani G. Cantele D. Ninno 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(2):143-154
In this work we show that the polaron effects in cylindrical quantum
wires are function of the cylinder radius R0 through the boundary conditions
for both the ionic and the electronic motion and through the size dependence of the static
and high frequency dielectric constants. We find that the dielectric constants
are increasing functions of R0. This fact and the different boundary conditions
for the ions and the electrons have the final consequence that polaron self-energy can
either be an increasing or a decreasing function of R0. 相似文献
3.
P. D. Sesion Jr. E. L. Albuquerque M. S. Vasconcelos P. W. Mauriz V. N. Freire 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):583-591
We study the acoustic-phonon spectra in periodic and quasiperiodic
(Fibonacci type) superlattices made up from III–V nitride materials
(GaN) intercalated by sapphire (Al2O3). Due to the
misalignments between the sapphire and the GaN layers that can lead
to threading dislocation densities as high as 108-1010
cm-1, and a significant lattice mismatch (~14%), the
phonon dynamics is described beyond the continuum elastic model
using coupled elastic and electromagnetic equations, stressing the
importance of the piezoelectric polarization field in a strained
condition. We use a transfer-matrix treatment to simplify the
algebra, which would be otherwise quite complicated, allowing a neat
analytical expressions for the phonon dispersion relation.
Furthermore, a quantitative analysis of the localization and
magnitude of the allowed band widths in the phonon's spectra, as
well as their scale law and the parametric spectrum of singularities
f(α), are presented and discussed. 相似文献
4.
P. T. Jochym K. Parlinski A. M. Oleś 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):173-179
The magnetization distribution, its energetic characterization by the
interlayer coupling constants and lattice dynamics of (001)-oriented
Fe/Pt multilayers are investigated using density functional theory
combined with the direct method to determine phonon frequencies.
It is found that ferromagnetic order between consecutive Fe layers is
favoured, with the enhanced magnetic moments at the
interface. The bilinear and biquadratic coupling coefficients between Fe
layers are shown to saturate fast with increasing thickness of
nonmagnetic Pt layers which separate them. The phonon calculations
demonstrate a rather strong dependence of partial iron phonon
densities of states on the actual position of Fe monolayer
in the multilayer structure. 相似文献
5.
Qingrong Zheng Gang Su Jian Wang Hong Guo 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):233-238
We report a theoretical analysis of the phonon thermal conductance, κ(T), for single wall carbon nanotubes (SWCN). In a range of low temperatues up to 100 K, κ(T) of perfect SWCN is found to increase with temperature, approximately, in a parabolic fashion. This is qualitatively consistent
with recent experimental measurements where the tube-tube interactions are negligibly weak. When the carbon-carbon bond length
is slightly varied, κ(T) is found to be qualitatively unaltered which implies that the anharmonic effect does not change the qualitative behavior
of κ(T).
Received 12 June 2001 相似文献
6.
Fluid and plastic flow dynamics of the critical state for a strongly pinned 2D superconductor 总被引:2,自引:0,他引:2
D. Monier L. Fruchter 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(2):201-205
The frequency of the Raman active A1g radial breathing mode has been widely used as a tool to estimate the distribution of diameters of single wall carbon nanotubes
(SWNT). However, the relation between frequency and diameter is not straightforward and results are model-dependent. Because
most of the experiments are performed on bundles and not on isolated tubes, the model should especially take into account
the van der Waals intertube interactions. Here, we use a pair-potential approach to account for such interactions and we derive
a nonlinear relation between the SWNT diameter and the frequency of the A1g radial breathing modes. We demonstrate a good agreement between calculations and the diameters derived from diffraction experiments
on the same samples.
Received 22 December 1999 and Received in final form 17 July 2000 相似文献
7.
X. Lü J.H. Chu 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):375-378
Thermal conductivity of silicon and porous silicon nanowires based on the equation of phonon radiative transport is theoretically
evaluated. The thermal conductivities of silicon nanowires with square cross-sections are found to match molecular dynamics
simulation results reasonably well. It is shown that the results of meso-porous silicon nanowires are about two orders of
magnitude lower than that of silicon nanowires in a wide range of temperature (50 K-300 K).
Received 24 April 2001 and Received in final form 23 December 2001 相似文献
8.
A. La Magna I. Deretzis V. Privitera 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(3):311-316
A method for the study of the electronic transport in strongly coupled electron-phonon systems is formalized and applied to
a model of polyyne chains biased through metallic Au leads. We derive a stationary non equilibrium polaronic theory in the
general framework of a variational
formulation. The numerical procedure we propose can be readily applied if the electron-phonon interaction in the device hamiltonian
can be approximated as an effective single particle electron hamiltonian. Using this approach, we predict that finite polyyne
chains should manifest an
insulator-metal transition driven by the non-equilibrium charging which inhibits the Peierls instability characterizing the
equilibrium state. 相似文献
9.
D.A. Tenne V.A. Haisler N.T. Moshegov A.I. Toropov A.P. Shebanin D.R.T. Zahn 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(3):371-376
We present the forward Raman scattering study of zone-centre optical phonon anisotropy in short-period GaAs/AlAs superlattices.
Experiments were performed on specially prepared superlattice structures having anti-reflection dielectric coatings and removed
substrates. The experimental data are compared with the angular dispersion of superlattice optical phonons calculated within
the dielectric susceptibility model. We have found a good agreement between the experimental data and the calculations taking
into account interface disorder.
Received 9 September 1998 and Received in final form 22 October 1998 相似文献
10.
P. D. SesionJr E. L. Albuquerque C. Chesman V. N. Freire 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(4):379-387
We study the acoustic-phonon transmission spectra in periodic and quasiperiodic (Fibonacci type) superlattices made up from
the III-V nitride materials AlN and GaN. The phonon dynamics is described by a coupled elastic and electromagnetic equations
within the static field approximation model, stressing the importance of the piezoelectric polarization field in a strained
condition. We use a transfer-matrix treatment to simplify the algebra, which would be otherwise quite complicated, allowing
a neat analytical expressions for the phonon transmission coefficients. Numerical results, for the normal incidence case,
show a strike self-similar pattern for both hexagonal (class 6 mm) and cubic symmetries crystalizations of the nitrides. 相似文献
11.
I. Bâldea H. Köppel L.S. Cederbaum 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(4):507-515
We investigate the Peierls transition in finite chains by exact (Lanczos) diagonalization and within a seminumerical method
based on the factorization of the electron-phonon wave function (Adiabatic Ansatz, AA). AA can be applied for mesoscopic chains
up to micrometer sizes and its reliability can be checked self-consistently. Our study demonstrates the important role played
for finite systems by the tunneling in the double well potential. The chains are dimerized only if their size N exceeds a critical value Nc which increases with increasing phonon frequency. Quantum phonon fluctuations yield a broad transition region. This smooth Peierls transition contrasts not only to the sharp mean field transition, but also with the sharp RPA soft mode instability,
although RPA partially accounts for quantum phonon fluctuations. For weak coupling the dimerization disappears below micrometer
sizes; therefore, this effect could be detected experimentally in mesoscopic systems.
Received: 3 January 1998 / Revised: 13 March 1998 / Accepted: 3 April 1998 相似文献
12.
A. Duda T. Paszkiewicz 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(3):327-331
We solved the problem of finding longitudinal acoustic directions of monoclinic media using the eliminant method. By extending
Khatkevich's approach and using the Bezout theorem, we proved that the number of longitudinal normals for mechanically stable
monoclinic media can not be larger than 13. Both longitudinal normals (n
1, n
2, n
3) lying in and out of plane perpendicular to the two-fold axis (n
3 ≠ 0) of monoclinic media are considered. Closed-form equations for ratios x = n
1/n
3 y = n
2/n
3 are derived and exactly solved by the eliminant method. With the help of this method, we show that in the case of the CDP
(CsH2PO4) crystal, the number of longitudinal normals equals three. Their components are given. For media of higher symmetries (rhombic,
trigonal, tetragonal, hexagonal and cubic), our approach yields well-known results obtained mainly by Borgnis and Khatkevich.
For triclinic elastic media, we proved that the number of degenerate directions can not be greater than 132.
Received 24 August 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: ardud@ift.uni.wroc.pl 相似文献
13.
E. Barborini I. N. Kholmanov A. M. Conti P. Piseri S. Vinati P. Milani C. Ducati 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):277-282
Nanostructured titanium dioxide films have been deposited
by supersonic cluster beam deposition (CBD). Nanoparticles are
produced by a pulsed microplasma cluster source (PMCS) and
selected by aerodynamic separation effects. The as-deposited
film is a complex mixture where amorphous material coexists, at
the nanoscale, with anatase and rutile crystal phases. The
nanocrystalline fraction of the film is characterized by crystal
size ranging from 100 nm to less than 5 nm. We have
characterized the film structure by transmission electron
microscopy, Raman spectromicroscopy, X-ray diffraction, and
UV-visible spectroscopy showing that correlations exist between
cluster size and film properties. In particular if very small
clusters are deposited, the film shows a predominant rutile
phase whereas larger clusters form films with mainly anatase
structure. Our observations suggest that phonon confinement
effects are responsible for a significant shift and broadening
observed for the Raman peaks. In addition, optical gap tuning is
provided by mass selection: large clusters assembling generates
a film with 3.22 eV optical gap, while smallest clusters 3.52
eV. 相似文献
14.
I. Milosević T. Vuković M. Damnjanović B. Nikolić 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(4):707-712
The full geometrical symmetry groups (the line groups) of the monolayered, 2Hb and 3R polytypes of the inorganic MoS2 and WS2 micro- and nanotubes of arbitrary chirality are found. This is used to find the coordinates of the representative atoms sufficient
to determine completely the geometrical structure of the tubes. Then some physical properties which can be deduced from the
symmetry are discussed: electron band degeneracies, selection rules, general forms of the second rank tensors and potentials,
phonon spectra.
Received 13 April 2000 相似文献
15.
Tian-You Fan Yiu-Wing Mai 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):25-27
This study extends the analysis of the vibrational spectrum of the one-dimensional hexagonal quasicrystal to the two-dimensional
quasicrystal with the 12mm point group. Several thermodynamic functions and the state equation of the material are shown.
Received 18 July 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: litongtzb@263.net 相似文献
16.
A. Milekhin N.P. Stepina A.I. Yakimov A.I. Nikiforov S. Schulze D.R.T. Zahn 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(2):355-359
Self-organised Ge dot superlattices grown by molecular beam epitaxy of Ge and Si layers utilizing Stranski-Krastanov growth
mode were investigated by Raman spectroscopy. An average size of Ge quantum dots was obtained from transmission electron microscopy
measurements. The strain and interdiffusion of Ge and Si atoms in Ge quantum dots were estimated from the analysis of frequency
positions of optical phonons observed in the Raman spectra. Raman scattering by folded longitudinal acoustic phonons in the
Ge dot superlattices was observed and explained using of elastic continuum theory.
Received 25 January 2000 相似文献
17.
A. S. Tchakoutio Nguetcho P. B. Ndjoko T. C. Kofane 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):7-14
The proton conductivity and the mobility arising from motions of the
ionic and bonded defects, in hydrogen-bonded molecular systems are
investigated by means of the quantum mechanical method. Our two component
model goes beyond the usual classical harmonic interaction by inclusion of a
quartic interaction potential between the nearest-neighbor protons. Among
the rich variety of soliton patterns obtained in this model, we focus our
attention to compact kink (kinkon) solutions to calculate analytically, the
mobility of the kinkon-antikinkon pair and the specific
electrical-conductivity of the protons transfer in the hydrogen-bonded
systems under an externally applied electrical-field through the dynamic
equation of the kinkon-antikinkon pair. For ice, the mobility and the
electrical conductivity of the proton transfer obtained are about
5.307×10-7 m2 V-1 s-1
and 6.11×10-4 Ω-1 m-1, respectively. The results
obtained are in qualitative agreement with experimental data. 相似文献
18.
A. S. Tchakoutio Nguetcho T. C. Kofane 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(4):411-422
The dynamics of protons in hydrogen-bonded quasi one-dimensional
networks are studied using a diatomic lattice model of protons and heavy ions
including a φ4 on-site substrate potential. It is shows that the model with
linear and nonlinear coupling of the quartic type between lattice sites for
the protons admits a richer dynamics that cannot be produced with linear
couplings alone. Depending on two types of physical boundary conditions, namely
of the drop or condensate type, and on conditions requiring the presence of
linear and nonlinear dispersion terms, soliton patterns of compact support,
whether with a peak, drop, bell, cusp, shock, kink, bubble or loop structure,
are obtained within a continuum approximation. Phase trajectories as well as analytical
studies provide information on the disintegration of soliton patterns upon
reaching some critical values of the lattice parameters. The total energies
of soliton patterns are computed exactly in the continuum limit. We also
show that when anharmonic interactions of the phonon are taken into account, the width and
energy of soliton patterns are in qualitative agreement with
experimental data. 相似文献
19.
E. Majerníková S. Shpyrko 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(2):259-269
The dynamics of excited phonon spectra of the E⊗e
Jahn-Teller (hereafter, JT) model mapped onto the generalized Calogero-Moser (gCM)
gas of pseudoparticles implies a complex interplay between nonlinearity
and fluctuations of quasiparticle trajectories. A
broad crossover appears in a pseudotime (interaction strength) between the
initial oscillator region and the nonlinear region of the
kink-train lattice as a superlattice of the kink-antikink gCM
trajectories. The local nonlinear fluctuations, nuclei (droplets) of
the growing kink phase arise at the crossover, forming a new
intermediate droplet “glassy” phase as a precursor of the kink
phase. The “glassy” phase is related to a broad maximum
in the entropy of the probability distributions of pseudoparticle
accelerations, or level curvatures. The kink-train lattice
phase with multiple kink-antikink collisions is stabilised by
long-range correlations when approaching a semiclassical limit.
A series of bifurcations of nearest-level spacings were recognised as signatures of pre-chaotic behaviour at the quantum level
in the kink phase.
Statistical characteristics can be seen to confirm the coexistence within all of
the spectra of both regularity and chaoticity to a varying extent (nonuniversality).
Regions are observed within which one of the phases is dominant. 相似文献
20.
A. Khelif B. Djafari-Rouhani Ph. Lambin 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(3):437-445
The vibrational and electronic spectra of a semi-infinite crystal with a planar surface are modified by the presence of surface
inhomogeneities or roughness such as ridges or grooves, quantum wires or tips. We develop a Green's function formalism to
investigate the localized and resonant acoustic modes of shear horizontal polarization associated with the surface of a substrate
supporting a single and a periodic array of wires. Each material is assumed to be an isotropic elastic medium. The calculation
can be applied to an arbitrary choice of the shape and elastic parameters of the wires. The surface modes are obtained as
well-defined peaks of the densities of states (DOS). In this paper, we calculate the variation of the density of states associated
with the adsorption of a single wire, and the dispersion curves of the surface modes for a periodic array of wires on the
flat surface of a substrate. We discuss their behaviors as a function of the elastic parameters and the relationship between
resonant modes of the single wire and dispersion curves of the surface modes for a periodic structure.
Received 6 December 2000 相似文献