共查询到20条相似文献,搜索用时 15 毫秒
1.
T. Grenet J. Delahaye M. Sabra F. Gay 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):183-197
We present a study of non-equilibrium phenomena observed
in the electrical conductance of insulating granular aluminium thin films.
An anomalous field effect and its slow relaxation are studied in some
detail. The phenomenology is very similar to the one already observed in
indium oxide. The origin of the phenomena is discussed. In granular systems,
the present experiments can naturally be interpreted along two different
lines. One relies on a slow polarisation in the dielectric surrounding the
metallic islands. The other one relies on a purely electronic mechanism: the
formation of an electron Coulomb glass in the granular metal. More selective
experiments and/or quantitative predictions about the Coulomb glass
properties are still needed to definitely distinguish between the two
scenarios. 相似文献
2.
T. Grenet 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):275-278
Conductivity and field effect measurements in thin insulating Al granular films are reported. The occurrence of a symmetrical
field effect and of very slow conductance relaxations is demonstrated. They are identical to the electron glassy behaviours
already reported in insulating indium oxide thin films. The results suggest that the phenomena are quite general. The study
of structurally discontinuous samples should help to understand the origin and mechanism of the glassy behaviour.
Received 4 December 2002 / Received in final form 26 February 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: thierry.grenet@grenoble.cnrs.fr 相似文献
3.
Y.-X. Wang S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(1):63-69
We investigate localization behavior of electron states in bilayer graphene formed with the Bernal stacking in the presence
of various types of disorder (site-energy, in-plane hopping and inter-plane hopping) by the use of the transfer matrix method.
It is found that all the states are localized at various kinds of disorder (site-energy, in-plane hopping and inter-plane
hopping) except that in the case of inter-plane-hopping disorder the states at the zero energy are critical. The implications
of the results are discussed. 相似文献
4.
E. Akkermans 《The European physical journal. E, Soft matter》2009,28(2):199-204
The storage and transmission of information is well defined using the notions of entropy, mutual information and channel capacity
as formalized by Shannon. These quantities are calculated for a quantum mesoscopic system in terms of scattering parameters.
For a one-dimensional system, the mutual information is related to the thermal conductance. This relation allows to show that
for an incident signal of power P, the channel capacity C has a universal upper bound given by C
independent of quantum statistics. A general framework is proposed which makes use of a natural underlying symplectic structure,
to relate the entropy of a quantum mesoscopic system to the scattering matrix. 相似文献
5.
R. Baltin Y. Gefen G. Hackenbroich H.A. Weidenmüller 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(1):119-129
We investigate the Coulomb blockade resonances and the phase of the transmission amplitude of a deformed ballistic quantum
dot weakly coupled to leads. We show that preferred single-particle levels exist which stay close to the Fermi energy for
a wide range of values of the gate voltage. These states give rise to sequences of Coulomb blockade resonances with correlated
peak heights and transmission phases. The correlation of the peak heights becomes stronger with increasing temperature. The
phase of the transmission amplitude shows lapses by between the resonances. Implications for recent experiments on ballistic quantum dots are discussed.
Received 17 July 1998 相似文献
6.
S. -H. Ouyang C. -H. Lam J. Q. You 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):67-72
We study electron transport through a quantum dot, connected to non-magnetic leads, in a magnetic field. A super-Poissonian
electron noise due to the effects of both interacting localized states and dynamic channel blockade is found when the Coulomb
blockade is partially lifted. This is sharp contrast to the sub-Poissonian shot noise found in the previous studies for a
large bias voltage, where the Coulomb blockade is completely lifted. Moreover, we show that the super-Poissonian shot noise
can be suppressed by applying an electron spin resonance (ESR) driving field. For a sufficiently strong ESR driving field
strength, the super-Poissonian shot noise will change to be sub-Poissonian. 相似文献
7.
C. C. Wang S. Jain A. O. Adeyeye 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(3):305-309
We investigate the magnetoresistance (MR) responses in a ferromagnetic
rectangular ring structure using a four-point probe technique. The measured
MR curves are strongly dependent on the electrical contact geometries used.
The associated MR characteristics are elucidated by a combination of
micromagnetic simulations and resistor-network based model, and the MR
contributions from different portions of the ring were studied
quantitatively. The systematic angular MR measured at the ring corner
further show that the locations of the domain wall nucleation are very
sensitive to the field alignment. 相似文献
8.
V. Moldoveanu I. V. Dinu B. Tanatar 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(2):231-238
We study the coherent transport in a one-dimensional lead with two side-coupled quantum dots using the Keldysh’s Green function
formalism.The effect of the interdot Coulomb interaction is taken into account by computing the firstand second order contributions
to the self-energy.We show that the Fano interference due to the resonance of one dotis strongly affected by the fixed parameters
that characterize the second dot. If the second dot is tuned close to resonance an additionalpeak develops between the peak
and dip of the Fano line shape of the current. In contrast, when the second dotis off-resonance and its occupation number
is close to unity the interdot Coulomb interaction merely shifts the Fano line and no other maxima appear.The system we consider
is more general than the single-dot interferometer studied experimentally by Kobayashi et al. [Phys. Rev. B 70, 035319 (2004)] and may be used for controlling quantum interference and studying decoherence effects in mesoscopic transport. 相似文献
9.
G. A. Appignanesi J. A. Rodriguez Fris F. Sciortino 《The European physical journal. E, Soft matter》2009,29(3):305-310
The picture of liquid water as consisting of a mixture of molecules of two different structural states (structured, low-density
molecules and unstructured, high-density ones) represents a belief that has been around for long time awaiting for a conclusive
validation. While in the last years some indicators have indeed provided certain evidence for the existence of structurally
different “species”, a more definite bimodality in the distribution function of a sound structural quantity would be desired.
In this context, our present work combines the use of a structural parameter with a minimization technique to yield neat bimodal
distributions in a temperature range within the supercooled liquid regime, thus clearly revealing the presence of two populations
of differently structured water molecules. Furthermore, we elucidate the role of the inter-conversion between the identified
two kinds of states for the dynamics of structural relaxation, thus linking structural information to dynamics, a long-standing
issue in glassy physics. 相似文献
10.
Y. Chushak A. Baumketner 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(1):129-136
The dynamical properties of liquid alloys are investigated by means of memory function equations and molecular-dynamics simulation.
A simple model for the second-order memory function in a binary liquid, based on Mori's memory function formalism, is proposed
and applied in numerical calculations of the time correlation functions and dynamic structure factor of liquid K0.7Cs0.3 and K0.3Cs0.7 alloys. Obtained results are discussed in comparison with the results of computer simulations.
Received: 27 February 1998 / Revised: 24 July 1998 / Accepted: 27 July 1998 相似文献
11.
E. Cuansing J.-S. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(4):505-513
We study quantum transport in honeycomb lattice ribbons with either
armchair or zigzag edges. The ribbons are coupled to semi-infinite
linear chains serving as the input and output leads and we use a
tight-binding Hamiltonian with nearest-neighbor hops. The input
and output leads are coupled to the ribbons through bar contacts.
In narrow ribbons we find transmission gaps for both types of edges.
The appearance of this gap is due to the enhanced quantum
interference coming from the multiple channels in bar contacts.
The center of the gap is at the middle of the band in ribbons with
armchair edges. This particle-hole symmetry is because bar
contacts do not mix the two sublattices of the underlying bipartite
honeycomb lattice when the ribbon has armchair edges. In
ribbons with zigzag edges the gap center is displaced to the right
of the band center. This breakdown of particle-hole symmetry is
the result of bar contacts now mixing the two sublattices. We also
find transmission oscillations and resonances within the transmitting
region of the band for both types of edges. Extending the length of
a ribbon does not affect the width of the transmission gap, as long
as the ribbon’s length is longer than a critical value when the gap
can form. Increasing the width of the ribbon, however, changes the
width of the gap. In ribbons with zigzag edges the gap width
systematically shrinks as the width of the ribbon is increased. In
ribbons with armchair edges the gap is not well-defined because of
the appearance of transmission resonances. We also find only
evanescent waves within the gap and both evanescent and propagating
waves in the transmitting regions. 相似文献
12.
M. Specht M. Sanquer S. Deleonibus G. Guégan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):503-508
We report observation of the Kondo effect in the Coulomb blockade oscillations of an impurity quantum dot (IQD). This IQD
is formed in the channel of a 100 nm gate length Silicon MOSFET. The quantitative analysis of the anomalous temperature and
voltage dependence for the drain-source current over a series of Coulomb blockade oscillations is performed. It strongly supports
the Kondo explanation for the conductance behavior at very low temperature in this standard microelectronics device.
Received 13 November 2001 and Received in final form 18 February 2002 相似文献
13.
Florian Elste Guillaume Weick Carsten Timm Felix von Oppen 《Applied Physics A: Materials Science & Processing》2008,93(2):345-354
Current-induced conformational switching in single-molecule junctions constitutes a fundamental process in molecular electronics.
Motivated by recent experiments on azobenzene derivatives, we study this process for molecules which exhibit two (meta)stable
conformations in the neutral state but only a single stable conformation in the ionic state. We derive and analyze appropriate
Fokker–Planck equations obtained from a density-matrix formalism starting from a generic model and present comprehensive analytical
and numerical results for the switching dynamics in general and the quantum yield in particular. 相似文献
14.
M. Pierre M. Hofheinz X. Jehl M. Sanquer G. Molas M. Vinet S. Deleonibus 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):475-481
We extend a simple model of a charge trap coupled to a single-electron box to energy ranges and parameters such that it gives
new insights and predictions readily observable in many experimental systems. We show that a single background charge is enough
to give lines of differential conductance in the stability diagram of the quantum dot, even within undistorted Coulomb diamonds.
It also suppresses the current near degeneracy of the impurity charge, and yields negative differential lines far from this
degeneracy. We compare this picture to two other accepted explanations for lines in diamonds, based respectively on the excitation
spectrum of a quantum dot and on fluctuations of the density-of-states in the contacts. In order to discriminate between these
models, we emphasize the specific features related to environmental charge traps. Finally we show that our model accounts
very well for all the anomalous features observed in silicon nanowire quantum dots. 相似文献
15.
R. A. Bordallo-Favela A. Ramírez-Saíto C. A. Pacheco-Molina J. A. Perera-Burgos Y. Nahmad-Molinari G. Pérez 《The European physical journal. E, Soft matter》2009,28(4):395-400
We present an experimental study of the spatial correlations of a quasi-two-dimensional dissipative gas kept in a non-static
steady state via vertical shaking. From high temporal resolution images we obtain the Pair Distribution Function (PDF) for
granular species with different restitution coefficients. Effective potentials for the interparticle interaction are extracted
using the Ornstein-Zernike equation with the Percus-Yevick closure. From both the PDFs and the corresponding effective potentials,
we find a clear increase of the spatial correlation at contact with the decreasing values of the restitution coefficient. 相似文献
16.
T. S. Li Y. C. Huang S. C. Chang Y. C. Chuang M. F. Lin 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):73-80
The electronic and thermal properties of AB-stacked bilayer graphene nanoribbons subject to the influences of a transverse
electric field are investigated theoretically, including their transport properties. The dispersion relations are found to
exhibit a rich dependence on the interlayer interactions, the field strength, and the geometry of the layers. The interlayer
coupling will modify the subband curvature, create additional band-edge states, change the subband spacing or energy gap,
and separate the partial flat bands. The bandstructures will be symmetric or asymmetric about the Fermi energy for monolayer
or bilayer nanoribbons, respectively. The inclusion of a transverse electric field will further alter the bandstructures and
lift the degeneracy of the partial flat bands. The chemical-potential-dependent electrical and thermal conductance exhibit
a stepwise increase behavior. Variations in the electronic structures with field strength will be reflected in the electrical
and thermal conductance. Prominent peaks, as well as single-shoulder and multi-shoulder structures in the electrical and thermal
conductance are predicted when varying the electric field strength. The features of the conductance are found to be strongly
dependent on the field strength, the geometry, interlayer interactions and temperature. 相似文献
17.
S.-G. Cheng Y. X. Xing X. C. Xie Q.-F. Sun 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(4):551-557
The Josephson current through an Aharonov-Bohm (AB)
interferometer, in which a quantum dot (QD) is situated on one arm
and a magnetic flux Φ threads through the ring, has been
investigated. In the presence of the magnetic flux, the relation
between the Josephson current and the superconductor phase is
complex, and the system can be adjusted to π junction by either
modulating the magnetic flux or the QD’s energy level
εd. Due to the electron-hole symmetry, the Josephson
current I has the property
I(εd,Φ)=I(-εd,Φ+π). The Josephson
current exhibits a jump when a pair of Andreev bound states aligns
with the Fermi energy. The condition for the current jump is given.
Particularly, we find that the position of the current jump and the
position of the maximum value of the critical current Ic are
identical. Due to the interference between the two paths, the
critical current Ic versus the QD’s level εd shows a
typical Fano shape, which is similar to the Fano effect in the
corresponding normal device. However they also show some
differences. For example, the critical current never reaches zero
for any parameters, while the current in the normal device can reach
zero at the destruction point. 相似文献
18.
We discuss here the effect of dissipation of relative angular momentum on fluctuations of excitation functions in dissipative heavy-ion collisions. Dissipation and fluctuation of relative angular momentum modify and smooth the time-angle localization of the rotating dinuclear system. The secondary maxima in the energy correlation function of the cross-section shift to smaller values of the energy difference, the shift depending on the relaxation time and the diffusion coefficient for angular-momentum dissipation. The results are illustrated for the collision28Si(E
lab=130 MeV)+48Ti.Partly supported by the Alexander von Humboldt Foundation 相似文献
19.
E. Khosravi S. Kurth G. Stefanucci E. K. U. Gross 《Applied Physics A: Materials Science & Processing》2008,93(2):355-364
Charge transport through a nanoscale junction coupled to two macroscopic electrodes is investigated for the situation when
bound states are present. We provide numerical evidence that bound states give rise to persistent, non-decaying current oscillations
in the junction. We also show that the amplitude of these oscillations can exhibit a strong dependence on the history of the
applied potential as well as on the initial equilibrium configuration. Our simulations allow for a quantitative investigation
of several transient features. We also discuss the existence of different timescales and address their microscopic origin. 相似文献
20.
Boor Singh Lalia K. Yamada M. S. Hundal Jin-Soo Park Gu-Gon Park Won-Yong Lee Chang-Soo Kim S. S. Sekhon 《Applied Physics A: Materials Science & Processing》2009,96(3):661-670
Polymer–ionic liquid composite electrolytes based on poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF–HFP) and room
temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium hexafluorophosphate (DMOImPF6) have been synthesized and studied. The addition of dimethylacetamide (DMA) and propylene carbonate (PC), both with high
dielectric constant and low viscosity, to polymer electrolytes has been found to result in an enhancement of conductivity
by one order of magnitude. Composite polymer electrolytes containing ionic liquid have been found to be thermally stable upto
300°C. Motional narrowing observed in the variation of line width of 1H and 19F NMR peaks with temperature suggests that both cations and anions are mobile in these electrolytes. 相似文献