共查询到20条相似文献,搜索用时 15 毫秒
1.
M. Leadbeater R. Raimondi P. Schwab C. Castellani 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(2):277-281
We report on the non-linear electric field effect in the conductivity of disordered conductors. We find that the electron-electron
interaction in the particle-hole triplet channel strongly affects the non-linear conductivity. The non-linear effect introduces
a field dependent temperature scale TE and provides a microscopic mechanism for electric field scaling at the metal-insulator transition. We also study the magnetic
field dependence of the non-linear conductivity and suggest possible ways to experimentally verify our predictions. These
effects offer a new probe to test the role of quantum interference at the metal-insulator transition in disordered conductors.
Received 9 February 2000 相似文献
2.
M. Terraneo I. Guarneri 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(2):303-309
We numerically analyze the distribution of scattering resonance widths in one- and quasi-one dimensional tight binding models,
in the localized regime. We detect and discuss an algebraic decay of the distribution, similar, though not identical, to recent
theoretical predictions.
Received 14 April 2000 and Received in final form 27 July 2000 相似文献
3.
Y.H. Yang Y.G. Wang M. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(4):455-459
Magnetic-impurity-scattering effects in a quasi-2D disordered electron system have been investigated theoretically with the
diagrammatic techniques in perturbation theory. The analytical expressions for magnetoconductivities due to weak-localization
effects have been obtained as functions of elastic, inelastic and magnetic scattering times. The relevant dimensional crossover
behavior from 3D to 2D with decreasing the interlayer coupling has been discussed, and the condition for the crossover has
been obtained.
Received 20 March 2001 and Received in final form 28 June 2001 相似文献
4.
A mixture of light and heavy atoms is considered. We study the kinetics
of the light atoms, scattered by the heavy ones, the latter undergoing slow
diffusive motion. In three-dimensional space we claim the
existence of a crossover region (in energy), which
separates the states of the light atoms with fast diffusion and the
states with slow diffusion; the latter is determined by the
dephasing time. For the two dimensional case we have a transition
between weak localization, observed when the dephasing length is
less than the localization length (calculated for static
scatterers), and strong localization observed in the opposite
case. 相似文献
5.
G. Benenti X. Waintal J.-L. Pichard D.L. Shepelyansky 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(3):515-521
Using Hartree-Fock orbitals with residual Coulomb repulsion, we study spinless fermions in a two-dimensional random potential.
When we increase the system size L at fixed particle density, the size dependence of the average inverse compressibility exhibits a smooth crossover from a
1/L
2 towards a 1/L decay when the Coulomb energy to Fermi energy ratio increases from 0 to 3. In contrast, the distribution of the first energy excitation displays a sharp Poisson-Wigner-like
transition at .
Received 13 March 2000 相似文献
6.
X.Q. Huang R.W. Peng F. Qiu S.S. Jiang A. Hu 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):275-281
We study in this paper, with the context of a tight-binding on-side model, the electronic properties of one-dimensional random
lattices with correlated impurities. We show that, when symmetrical impurities
are inserted in a host chain of site energy and a constant hopping interaction V, diffusion will occur even when is random. We provide analytic expressions for the transmittance and confirm the theoretical results by a great deal of numerical
calculations. When = V, we find that the mean-square displacement (MSD) follows the law
m
2
∝t
β with β = 2.0 for = constant and β = 1.0 for = = random, respectively.
Received 15 January 2001 and Received in final form 30 April 2001 相似文献
7.
P. Schwab R. Raimondi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):5-8
We consider non-equilibrium transport in disordered conductors. We calculate the interaction correction to the current for
a short wire connected to electron reservoirs by resistive interfaces. In the absence of charging effects we find a universal
current-voltage-characteristics. The relevance of our calculation for existing experiments is discussed as well as the connection
with alternative theoretical approaches.
Received 2 September 2002 Published online 29 October 2002 相似文献
8.
L. Bartosch P. Kopietz 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):29-36
We consider the effect of Coulomb interactions on the average density of states (DOS) of disordered low-dimensional metals
for temperatures T and frequencies ω smaller than the inverse elastic life-time 1/τ. Using the fact that long-range Coulomb interactions in two dimensions (2d) generate ln2-singularities in the DOS ν(ω) but only ln-singularities in the conductivity σ(ω), we can re-sum the most singular contributions
to the average DOS via a simple gauge-transformation. If σ(ω) > 0, then a metallic Coulomb gapν(ω) ∝ |ω|/e
4 appears in the DOS at T = 0 for frequencies below a certain crossover frequency Ω
2 which depends on the value of the DC conductivity σ(0). Here, - e is the charge of the electron. Naively adopting the same procedure to calculate the DOS in quasi 1d metals, we find ν(ω) ∝ (|ω|/Ω
1)1/2exp(- Ω
1/|ω|) at T = 0, where Ω
1 is some interaction-dependent frequency scale. However, we argue that in quasi 1d the above gauge-transformation method is on less firm grounds than in 2d. We also discuss the behavior of the DOS at finite temperatures and give numerical results for the expected tunneling conductance
that can be compared with experiments.
Received 28 August 2001 / Received in final form 28 January 2002 Published online 9 July 2002 相似文献
9.
G.N. Katomeris S.N. Evangelou 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(1):133-136
We examine the validity of the recently proposed semi-Poisson level spacing distribution function P(S), which characterizes “critical quantum chaos”, in 2D disordered systems with spin-orbit coupling. At the Anderson transition
we show that the semi-Poisson P(S) can describe closely the critical distribution obtained with averaged boundary conditions, over Dirichlet in one direction
with periodic in the other and Dirichlet in both directions. We also obtain a sub-Poisson linear number variance , with asymptotic value . The obtained critical statistics, intermediate between Wigner and Poisson, is discussed for disordered systems and chaotic
models.
Received 1 September 1999 相似文献
10.
D.V. Livanov E.I. Isaev Yu.Kh. Vekilov S.I. Manokhin A.S. Mikhaylushkin S.I. Simak 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):119-126
Al-Si solid solutions synthesized under high pressure demonstrate striking physical properties, such as enhanced superconductivity
and peculiarities of low-temperature transport coefficients. In order to understand the connection of these effects to the
electronic structure changes we have performed a first-principles study of the electronic spectra and Fermi surfaces of Al-Si
solid solutions. We show that two electronic topological transitions (ETT's) lead to unusual concentration dependencies of
the resistivity, thermoelectric power and Hall constant of the system while a variety of other interesting phenomena such
as lattice instability and superconductivity enhancement may be a result of the nesting features appearing upon Si doping.
We present also the results of our theoretical calculations of the thermodynamic and transport properties of Al-Si solid solutions
which are in good agreement with experiment and reproduce nicely the experimentally observed peculiarities.
Received 31 January 2002 相似文献
11.
A. Politi S. Ruffo L. Tessieri 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):673-679
We have investigated numerically the quantum evolution of a -like wave-packet in a quenched disordered medium described by a tight-binding Hamiltonian with long-range hopping (band random
matrix approach). We have obtained clean data for the scaling properties in time and in the bandwidth b of the packet width and its fluctuations with respect to disorder realizations. We confirm that the fluctuations of the packet width in the steady-state show an anomalous
scaling [0pt] with [0pt] . This can be related to the presence of non-Gaussian tails in the distribution of [0pt]. Finally, we have analysed the steady state probability profile and we have found 1/b corrections with respect to the theoretical formula derived by Zhirov in the limit, except at the origin, where the corrections are .
Received 6 August 1999 and Received in final form 22 October 1999 相似文献
12.
M.L. Ndawana R.A. Römer M. Schreiber 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):399-407
We compute the number level variance Σ
2 and the level compressibility χ from high precision data for the Anderson model of localization and show that they can be
used in order to estimate the critical properties at the metal-insulator transition by means of finite-size scaling. With
N, W, and L denoting, respectively, linear system size, disorder strength, and the average number of levels in units of the mean level
spacing, we find that both χ(N, W) and the integrated Σ
2 obey finite-size scaling. The high precision data was obtained for an anisotropic three-dimensional Anderson model with disorder
given by a box distribution of width W/2. We compute the critical exponent as ν≈ 1.45±0.12 and the critical disorder as W
c≈ 8.59±0.05 in agreement with previous transfer-matrix studies in the anisotropic model. Furthermore, we find χ≈ 0.28±0.06
at the metal-insulator transition in very close agreement with previous results.
Received 1st November 2001 and Received in final form 8 March 2002 Published online 6 June 2002 相似文献
13.
F.B. Anders M. Huth 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(4):491-499
We present calculations of the electronic transport properties of heavy-fermion systems within a semi-phenomenological approach
to the dynamical mean field theory. In this approach the dynamics of the Hund's rules 4f (5f )-ionic multiplet split in a crystalline environment is taken into account. Within the scope of this calculation we use the
linear response theory to reproduce qualitative features of the temperature-dependent resistivity and hall conductivity, the
magneto-resistivity and the thermoelectric power typical for heavy-fermion systems. The model calculations are directly compared
with experimental results on CeCu
2
Si
2.
Received 30 June 2000 and Received in final form 15 December 2000 相似文献
14.
D. F. Martinez R. A. Molina 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(2):281-290
We generalize the definition of localization length to
disordered systems driven by a time-periodic potential using a
Floquet-Green function formalism. We study its dependence on the
amplitude and frequency of the driving field in a one-dimensional
tight-binding model with different amounts of disorder in the
lattice. As compared to the autonomous system, the localization
length for the driven system can increase or decrease depending on
the frequency of the driving. We investigate the dependence of the
localization length with the particle's energy and prove that it
is always periodic. Its maximum is not necessarily at the band
center as in the non-driven case. We study the adiabatic limit by
introducing a phenomenological inelastic scattering rate which
limits the delocalizing effect of low-frequency fields. 相似文献
15.
C. Furtlehner 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(2):297-301
Localization of an electron moving in two dimensions, submitted to a strong magnetic field and scattered by randomly distributed
zero-range impurities is investigated. Considering the explicit expression for the density of states obtained by Brézin, Gross
and Itzykson, the Lifshitz argument is adapted in order to analyze the unusual power-law behavior of the low energy spectrum.
When the impurity density is smaller than the Landau degeneracy, typical configurations of disorder responsible for low energy
states are identified as cluster of impurities of well defined form. This allows for an interpretation of low-lying states,
localized around these clusters, whose size diverges logarithmically as the energy goes to zero.
Received 5 January 2000 相似文献
16.
M. Kolář F. Slanina 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(3):379-384
We examine a model of biological evolution of Eigen's quasispecies in a so-called holey fitness landscape, where the fitness
of a site is either 0 (lethal site) or a uniform positive constant (viable site). The evolution dynamics is therefore determined
by the topology of the genome space which is modelled by the random Bethe lattice. We use the effective medium and single-defect
approximations to find the criteria under which the localized quasispecies cloud is created. We find that shorter genomes,
which are more robust to random mutations than average, represent a selective advantage which we call “topological”. A way
of assessing empirically the relative importance of reproductive success and topological advantage is suggested.
Received 9 August 2002 / Received in final form 7 November 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: slanina@fzu.cz 相似文献
17.
B.S. Pavlov I.Yu. Popov S.V. Frolov 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(2):283-287
The problem of construction of quantum multiplexer is discussed. A possible construction based on resonance transport properties
of quantum waveguides coupled through small windows is considered. Small apertures play double role of “connecting channels"
and “resonant elements". Transmission coefficients for the system are determined. The workability of the device as a quantum
switch to one of three (or to two of three) channels is discussed. Control parameters for the switch are electron energy and
bias voltage.
Received 13 August 2000 and Received in final form 19 February 2001 相似文献
18.
P. Liu S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):513-516
The spin Hall transport properties in a two-dimensional electron
system with both Rashba spin-orbit coupling (SOC) and magnetic
impurities are investigated. Electrons are scattered by impurities
through an exchange interaction that leads to spin flip-flop
processes and so changes the spin Hall effect induced by the SOC.
The spin Hall conductance is calculated in a 4-terminal system
using the Landauer-Buttiker formula and Green function approach.
In comparison with the simulation results on nonmagnetic
impurities doping systems, our results reveal that the spin Hall
conductance is still nonzero in a system with a large density of
magnetic impurities and a finite intensity of the exchange
interaction between the electrons and impurities, and its sign may
be altered when the doping density and interaction strength are
large enough. 相似文献
19.
M. Auslender E. Kogan 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(4):525-529
We study density of states and conductivity of the doped double-exchange system, treating interaction of charge carriers both
with the localized spins and with the impurities in the coherent potential approximation. It is shown that under appropriate
conditions there is a gap between the conduction band and the impurity band in paramagnetic phase, while the density of states
is gapless in ferromagnetic phase. This can explain metal-insulator transition frequently observed in manganites and magnetic
semiconductors. Activated conductivity in the insulator phase is numerically calculated.
Received 13 June 2000 and Received in final form 5 January 2001 相似文献
20.
P. Schwab R. Raimondi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(4):483-495
We show that in the metallic phase of a two dimensional electron gas the spin-orbit coupling due to structure inversion asymmetry
leads to a characteristic anisotropy in the magnetoconductance. Within the assumption that the metallic phase can be described
by a Fermi liquid, we compute the conductivity in the presence of an in-plane magnetic field. Both the spin-orbit coupling
and the Zeeman coupling with the magnetic field give rise to two spin subbands, in terms of which most of the transport properties
can be discussed. The strongest conductivity anisotropy occurs for Zeeman energies of the order of the Fermi energy corresponding
to the depopulation of the upper spin subband. The energy scale associated with the spin-orbit coupling controls the strength
of the effect. More in particular, we find that the detailed behavior and the sign of the anisotropy depends on the underlying
scattering mechanism. Assuming small angle scattering to be the dominant scattering mechanism our results agree with recent
measurement on Si-MOSFET's in the vicinity of the metal-insulator transition.
Received 11 July 2001 相似文献