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1.
J.E. Lorenzo H. Requardt 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):185-186
Eur. Phys. J. B 24, 315 (2001) Here we comment on a recently published paper on the presence of a phason contribution in the low temperature heat capacity data of the charge-density-wave compounds K0.3MoO3 and (TaSe4)2I. We have shown that the anomaly in the C
P
/
T
3
data reported by Odin et al. is straightforwardly interpreted in terms of low energy phonon modes resulting from the peculiar topology of these compounds.
Received 21 February 2002 Published online 19 July 2002 相似文献
2.
3.
We report on the reflectance of blue bronze crystals in the visible frequency range as a function of temperature. The observed large oscillations in the reflectance at all wavelengths at temperatures near the Peierls transition are interpreted as interference effects stemming from a surface layer. It is found that the surface layer, which appears to be tied to fluctuations, can be as much as 1.6 microns thick. 相似文献
4.
One-particle properties of the spinless fermion model with repulsion at half filling are calculated within an approach correct to first order in the inverse of the lattice dimensiond. Continuity of the limitd requires a scaling of the nearest-neighbour hopping proportional to
and of the nearest-neighbour interaction proportional to 1/d. Due to this scaling the Hartree approximation becomes exact in infinite dimensions. We show that 1/d corrections comprise the Fock diagram and the local correlation diagram in the self-consistent Dyson equation. This approach is applied to simple-cubic systems in dimensiond=1, 2 and 3. Ground state properties and the charge-density wave phase diagram are calculated. AtT=0 the inclusion of 1/d terms gives only small corrections to the leading Hartree contribution ind=2, 3. ForT>0, however, the 1/d corrections are important. They lead to a non-negligible reduction of the critical temperature. Ind=1 the 1/d corrections are very large, but they do not succeed in removing the spurious phase transition atT>0. The 1/d approach provides a good and tractable approximation ind=3 and probably ind=2, which allows also further systematic improvement. 相似文献
5.
We found, through extensive experimental studies, that the physical aging effects are absent in the relaxation of rubbing-induced
birefringence (RIB) in polystyrene (PS), and the relaxation involves very small length scale. A phenomenological model based
on individual birefringence elements is proposed for the RIB relaxation. The relaxation times (RTs) of the elements are found
to be independent of the thermal or stress history of the samples, either before or after the formation of the birefringence.
The RTs are also independent of the molecular weight, rubbing conditions, and film thickness, while the RTs distribution function
does depend on the molecular weight and rubbing conditions. The model provides quantitative interpretations that agree very
well with all the reported experimental results, and sheds important light on the novel behaviors of the RIB relaxation. The
absence of physical aging effects is probably due to the combined effects of small length scale of the RIB relaxation, and
the accelerated aging speed in the near surface region in which the RIB concentrates. 相似文献
6.
Junfeng Wang Di Yin Zhengyou Liu Decheng Tian Yuheng Zhang 《Solid State Communications》2004,132(10):653-656
The thermoelectric power (TEP) of the quasi-one-dimensional charge-density-wave (CDW) conductors rubidium blue bronze Rb0.3MoO3 and its alloy Rb0.15K0.15MoO3 were measured in the temperature range 80-280 K. The result showed a sign change from a small positive value to a great negative value where the Peierls transition temperatures (Tp) are 183 and 180 K for Rb0.3MoO3 and Rb0.15K0.15MoO3, respectively. Above Tp, the TEP for both samples can be described with the empirical relation S=AT+B; while below Tp, the TEP fits well the relation S=AT+B/T based on the experimental data. The Fermi energies εF for Rb0.3MoO3 and Rb0.15K0.15MoO3 are estimated to be 1.55 and 0.53 eV, respectively. 相似文献
7.
S.V. Dordevic D.N. Basov R.C. Dynes B. Ruzicka V. Vescoli L. Degiorgi H. Berger R. Gaál L. Forró E. Bucher 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):15-23
We present a comprehensive analysis of the optical constants of the two-dimensional dichalcogenide materials 2
H
-
TaSe
2
and 2
H
-
NbSe
2
, in an attempt to address the physics of two-dimensional correlated systems. The title compounds were studied over several
decades in frequency, from the far-infrared to the ultraviolet. Measurements with linearly polarized light have allowed us
to obtain both the in-plane and out-of-plane components of the conductivity tensor. Although the electromagnetic response
of dichalcogenides is strongly anisotropic, both the in-plane and out-of-plane components of the conductivity tensor share
many common features, including the presence of a well-defined metallic component, as well as a “mid-infrared band”. We discuss
the implications of these results in the context of the spectroscopic results of other classes of low-dimensional conductors
such as the high-temperature superconducting cuprates. In particular, the analysis of the redistribution of the spectral weight
as a function of temperature, as well as the behavior of the quasiparticles relaxation rate, points to significant distinctions
between the charge dynamics of dichalcogenides and other classes of low dimensional conductors.
Received 28 October 2002 / Received in final form 10 March 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: degiorgi@solid.phys.ethz.ch 相似文献
8.
H. Fehske A.P. Kampf M. Sekania G. Wellein 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):11-16
In order to clarify the physics of the crossover from a Peierls band insulator to a correlated Mott-Hubbard insulator, we
analyze ground-state and spectral properties of the one-dimensional half-filled Holstein-Hubbard model using quasi-exact numerical
techniques. In the adiabatic limit the transition is connected to the band to Mott insulator transition of the ionic Hubbard
model. Depending on the strengths of the electron-phonon coupling and the Hubbard interaction the transition is either first
order or evolves continuously across a narrow intermediate phase with finite spin, charge, and optical excitation gaps.
Received 7 July 2002 / Received in final form 21 October 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: holger.fehske@physik.uni-greifswald.de 相似文献
9.
The η-Mo4O11 compound is a layered two-dimensional (2D) metallic system whose reduced dimensionality originates non-linear properties as charge density wave (CDW) instabilities. We report on synchrotron radiation angle resolved photoemission spectroscopy (ARPES) measurements in order to obtain a detailed picture of the electronic structure of this material. The symmetry of the states near the Fermi level (EF) has been discussed in relation to the photoemission symmetry selections rules. Our results are in excellent agreement with previous tight-binding calculations and support the hidden nesting concept proposed to explain the CDW instabilities exhibited by this family of compounds. In addition, a very peculiar photoemission line-shape has been found with the presence of localized non-dispersive states. Some possible explanations are discussed. 相似文献
10.
All-Optical RZ-to-NRZ Format Conversion with a Tunable Fibre Based Delay Interferometer 总被引:1,自引:0,他引:1
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All-optical format conversion from return-to-zero (RZ) to non-return-to-zero (NRZ) is demonstrated with temperaturecontrolled all-fibre delay interferometer (DI) at 20 Gb/s. The operation principle is theoretical analysed with the help of numerical simulation and spectra analysis. Theoretical analysis results are consistent well with the experimental results. The format conversion can be achieved with power penalty of 0.54 dB and with output extinction ratio 20 dB. 相似文献