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1.
R. Citro M. Marinaro 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):55-60
Within a strong-coupling perturbative approach, based on a Cumulant Expansion of the extended single-band Hubbard model, we
show that the on-shell inverse scattering time deviates from the normal Fermi-liquid behavior near the points of the Fermi
surface connected by the characteristic wave-vector of an incommensurate charge density wave. The violation of the Fermi liquid
behavior is associated with a square root behavior of the inverse quasiparticle lifetime in proximity of a stripe phase. Some
relevant features observed in ARPES experiments on Bi2212 are qualitatively reproduced.
Received 28 February 2002 / Received in final form 7 May 2002 Published online 9 July 2002 相似文献
2.
M. Modarres H.R. Moshfegh A. Sepahvand 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(2):159-166
The free energy of the homogeneous electron fluid at finite temperature is obtained using the lowest order constrained variational
(LOCV) method. In order to test the convergence of cluster expansion series the three-body cluster terms are calculated with
the LOCV correlation functions. The results agree reasonably with those of Monte Carlo, coupled-cluster, perturbational expansion
etc, techniques at zero temperature. The flashing and critical temperatures as well as the critical exponent are found to
be about 0.6, 1.3 eV and 0.384 respectively. A similar liquid-gas phase transition to that of nuclear matter and liquid He3 is observed.
Received 15 April 2002 / Received in final form 19 October 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: modarres@khayam.ut.ac.ir 相似文献
3.
Y. Ōno R. Bulla A.C. Hewson M. Potthoff 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(3):283-290
We have studied the critical behaviour of a doped Mott insulator near the metal-insulator transition for the infinite-dimensional
Hubbard model using a linearized form of dynamical mean-field theory. The discontinuity in the chemical potential in the change
from hole to electron doping, for U larger than a critical value U
c, has been calculated analytically and is found to be in good agreement with the results of numerical methods. We have also
derived analytic expressions for the compressibility, the quasiparticle weight, the double occupancy and the local spin susceptibility
near half-filling as functions of the on-site Coulomb interaction and the doping.
Received 15 March 2001 and Received in final form 22 May 2001 相似文献
4.
R. Staudt M. Dzierzawa A. Muramatsu 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):411-415
We investigate the phase diagram of the three-dimensional Hubbard model at half filling using quantum Monte Carlo (QMC) simulations.
The antiferromagnetic Néel temperature is determined from the specific heat maximum in combination with finite-size scaling of the magnetic structure factor. Our
results interpolate smoothly between the asymptotic solutions for weak and strong coupling, respectively, in contrast to previous
QMC simulations. The location of the metal-insulator transition in the paramagnetic phase above is determined using the electronic compressibility as criterion.
Received 11 April 2000 and Revised in final form 29 June 2000 相似文献
5.
Z. Gulácsi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):295-301
We report for the first time exact ground-states deduced for the D
= 2 dimensional generic periodic Anderson model at finite U, the Hamiltonian of the model not containing direct hopping terms for f-electrons (
t
f
= 0). The deduced itinerant phase presents non-Fermi liquid properties in the normal phase, emerges for real hybridization matrix
elements, and not requires anisotropic unit cell. In order to deduce these results, the plaquette operator procedure has been
generalised to a block operator technique which uses blocks higher than an unit cell and contains f-operator contributions acting only on a single central site of the block.
Received 1st July 2002 / Received in final form 16 September 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: gulacsi@heavy-ion.atomki.hu 相似文献
6.
An analysis of Luttinger's theorem shows that – contrary to recent
claims – it is not valid for a generic Mott insulator. For a
two-orbital Hubbard model with two electrons per site the crossover
from a non-magnetic correlated insulating phase (Mott or Kondo
insulator) to a band insulator is investigated. Mott insulating
phases are characterized by poles of the self-energy and
corresponding zeros in the Greens functions defining a “Luttinger
surface” which is absent for band insulators. Nevertheless, the
ground states of such insulators with two electrons per unit cell
are adiabatically connected. 相似文献
7.
M. Abbate J.A. Guevara S.L. Cuffini Y.P. Mascarenhas E. Morikawa 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):203-208
We studied the changes in the electronic structure of SrTi1-xRuxO3 across the metal-insulator transition. The parent compound, SrTiO3, is a well known diamagnetic insulator; whereas the doped compound, SrTi1-xRuxO3, becomes a ferromagnetic metal above x
C
= 0.35. The techniques used in the study were photoemission (PES) and O 1
s X-ray absorption (XAS) spectroscopy. The experimental spectra were analyzed in terms of band structure and Hubbard model
calculations. The PES and XAS spectra of SrTi1-xRuxO3 show the Ru 4
d bands growing in the band gap of SrTiO3 . The analysis in terms of the Hubbard model indicates that the Ti 3
d and Ru 4
d bands are mostly decoupled. This suggests that the metal-insulator transition is a percolation transition like that of metals
embedded in a rare gas matrix. Electron correlation effects are present in this system, but they do not seem to play a major
role in the transition.
Received 10 September 2001 相似文献
8.
S. Pairault D. Sénéchal A.-M.S. Tremblay 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(1):85-105
The strong-coupling perturbation theory of the Hubbard model is presented and carried out to order (t/U)5 for the one-particle Green function in arbitrary dimension. The spectral weight is expressed as a Jacobi continued fraction and compared with new Monte-Carlo data of the one-dimensional, half-filled Hubbard
model. Different regimes (insulator, conductor and short-range antiferromagnet) are identified in the temperature-hopping
integral (T,t) plane. This work completes a first paper on the subject (Phys. Rev. Lett. 80, 5389 (1998)) by providing details on diagrammatic rules and higher-order results. In addition, the non half-filled case,
infinite resummations of diagrams and the double occupancy are discussed. Various tests of the method are also presented.
Received 25 October 1999 相似文献
9.
G.I. Japaridze S. Sarkar 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):139-144
A one-dimensional model of interacting electrons with on-site U, nearest-neighbor V, and pair-hopping interaction W is studied at half-filling using the continuum limit field theory approach. The ground state phase diagram is obtained for
a wide range of coupling constants. In addition to the insulating spin-density wave (SDW) and charge-density wave (CDW) phases
for large U and V, respectively, we identify a bond-charge-density-wave (BCDW) phase W < 0, | U - 2V| < | 2W| and a bond-spin-density-wave (BSDW) for W > 0, | U - 2V| < W. The possibility of bond-located ordering results from the site-off-diagonal nature of the pair-hopping term and is a special
feature of the half-filled band case. The BCDW phase corresponding to an enhanced Peierls instability in the system. The BdSDW
is an unconventional insulating magnetic phase, characterized by a gapless spin excitation spectrum and a staggered magnetization
located on bonds between sites. The general ground state phase diagram including insulating, metallic, and superconducting
phases is discussed. A transition to the η-superconducting phase at | U - 2V| ≪ 2t?W is briefly discussed.
Received 20 February 2002 / Received in final form 11 April 2002 Published online 19 July 2002 相似文献
10.
M. Krawiec B.L. Györffy J.F. Annett 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(2):163-176
We study the ground state properties of a superconductor-ferromagnet-insulator trilayer on the basis of a Hubbard Model featuring
exchange splitting in the ferromagnet and electron-electron attraction in the superconductor. We solve the spin-polarized
Hartree-Fock-Gorkov equations together with the Maxwell's equation (Ampere's law) fully self-consistently with respect to
the order parameter and the current. For certain values of the exchange splitting we find that a spontaneous spin polarized
current is generated in the ground state and is intimately related to Andreev bound states at the Fermi level. Moreover, the
polarization of the current strongly depends on the band filling.
Received 23 September 2002 / Received in final form 13 December 2002 Published online 1st April 2003
RID="a"
ID="a"e-mail: m.a.krawiec@bristol.ac.uk 相似文献
11.
Recent experiments have demonstrated that the dynamics in liquids close to the glass transition temperature is strongly heterogeneous.
The characteristic size of these heterogeneities has been measured to be a few nanometers at T
g. We extend here a recent model for describing the heterogeneous nature of the dynamics which allows both to derive this length
scale and the right orders of magnitude of the heterogeneities of the dynamics close to the glass transition. Our model allows
then to interpret quantitatively small probes diffusion experiments.
Received 29 March 2002 and Received in final form 11 November 2002
RID="a"
ID="a"e-mail: long@lps.u-psud.fr 相似文献
12.
13.
Y. Ōno R. Bulla A.C. Hewson 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):375-384
The Mott metal-insulator transition in the two-band Hubbard model in infinite dimensions is studied by using the linearized
dynamical mean-field theory recently developed by Bulla and Potthoff. The phase boundary of the metal-insulator transition
is obtained analytically as a function of the on-site Coulomb interaction at the d-orbital, the charge-transfer energy between the d- and p-orbitals and the hopping integrals between p-d, d-d and p-p orbitals. The result is in good agreement with the numerical results obtained from the exact diagonalization method.
Received 5 October 2000 and Received in final form 8 December 2000 相似文献
14.
W.Z. Wang K.L. Yao 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):437-441
A ferrimagnetic polymer with m-phenylene skeleton as coupling unit is studied with the Hubbard model in the self-consistent mean-field theory. The ferrimagnetic
ground state with a total spin S = 1 per unit cell is obtained and originates from the antiferromagnetic correlations between the nearest neighbors. If the
on-site electron-electron repulsions at the radical sites and at the phenylene ring sites are different, the gap in energy
band structure may disappear and the ferrimagnetic ground state becomes unstable. The charge density and spin density can
transfer between the radical sites and the phenylene ring sites due to the competition between the hopping integral and the
on-site repulsion at different sites.
Received 15 July 2002 Published online 31 December 2002 相似文献
15.
M. Tsuchiizu P. Donohue Y. Suzumura T. Giamarchi 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):185-193
We investigate the physical properties of two coupled chains of electrons, with a nearly half-filled band, as a function of
the interchain hopping t
⊥ and the doping. We show that upon doping, the system undergoes a metal-insulator transition well described by a commensurate-incommensurate
transition. By using bosonization and renormalization we determine the full phase diagram of the system, and the physical
quantities such as the charge gap. In the commensurate phase two different regions, for which the interchain hopping is relevant
and irrelevant exist, leading to a confinement-deconfinement crossover in this phase. A minimum of the charge gap is observed
for values of t
⊥ close to this crossover. At large t
⊥ the region of the commensurate phase is enhanced, compared to a single chain. At the metal-insulator transition the Luttinger
parameter takes the universal value K
ρ
* = 1, in agreement with previous results on special limits of this model.
Received 31 July 2000 相似文献
16.
We introduce a solid-on-solid growth process which evolves by random deposition of dimers, surface diffusion, and evaporation
of monomers from the edges of plateaus. It is shown that the model exhibits a robust transition from a smooth to a rough phase.
The roughening transition is driven by an absorbing phase transition at the bottom layer of the interface, which displays
the same type of critical behavior as the pair contact process with diffusion 2A↦3A, 2A↦.
Received 14 October 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: Haye.Hinrichsen@physik.uni-wuppertal.de 相似文献
17.
We study the force-induced unfolding of random disordered RNA or single-stranded DNA polymers. The system undergoes a second-order
phase transition from a collapsed globular phase at low forces to an extensive necklace phase with a macroscopic end-to-end
distance at high forces. At low temperatures, the sequence inhomogeneities modify the critical behaviour. We provide numerical
evidence for the universality of the critical exponents which, by extrapolation of the scaling laws to zero force, contain
useful information on the ground-state (f = 0) properties. This provides a good method for quantitative studies of scaling exponents characterizing the collapsed globule.
In order to get rid of the blurring effect of thermal fluctuations, we restrict ourselves to the ground state at fixed external
force. We analyze the statistics of rearrangements, in particular below the critical force, and point out its implications
for force-extension experiments on single molecules.
Received 18 June 2002 and Received in final form 23 September 2002
RID="a"
ID="a"e-mail: muller@ipno.in2p3.fr 相似文献
18.
P. Korbel W. Wójcik A. Klejnberg J. Spałek M. Acquarone M. Lavagna 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):315-322
We supplement (and critically overview) the existing extensive analysis of antiferromagnetic solution for the Hubbard model
with a detailed discussion of two specific features, namely (i) the evolution of the magnetic (Slater) gap (here renormalized
by the electronic correlations) into the Mott-Hubbard or atomic gap, and (ii) a rather weak renormalization of the effective
mass by the correlations in the half-filled-band case, which contrasts with that for the paramagnetic case. The mass remains
strongly enhanced in the non-half-filled-band case. We also stress the difference between magnetic and non-magnetic contributions
to the gap. These results are discussed within the slave boson approach in the saddle-point approximation, in which there
appears a non-linear staggered molecular field due to the electronic correlations that leads to the appearance of the magnetic gap. They reproduce correctly the ground-state energy in the limit of strong correlations. A brief comparison with the solution
in the limit of infinite dimensions and the corresponding situation in the doubly-degenerate-band case with one electron per
atom is also made.
Received 16 December 2002 / Received in final form 5 February 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: ufspalek@if.uj.edu.pl 相似文献
19.
20.
A nanosecond scale in situ probe reveals that a bulk linear polymer undergoes a sharp phase transition as a function of the degree of conversion, as
it nears the glass transition. The scaling behaviour is in the same universality class as percolation. The exponents γ and
β are found to be 1.7±0.1 and 0.41±0.01 in agreement with the best percolation results in three dimensions.
Received 29 August 2002
RID="a"
ID="a"e-mail: erzan@gursey.gov.tr e-mail: erzan@itu.edu.tr 相似文献