39,907 research outputs found
Doping dependent charge injection and band alignment in organic field-effect transistors
We have studied metal/organic semiconductor charge injection in
poly(3-hexylthiophene) (P3HT) field-effect transistors with Pt and Au
electrodes as a function of annealing in vacuum. At low impurity dopant
densities, Au/P3HT contact resistances increase and become nonohmic. In
contrast, Pt/P3HT contacts remain ohmic even at far lower doping. Ultraviolet
photoemission spectroscopy (UPS) reveals that metal/P3HT band alignment shifts
dramatically as samples are dedoped, leading to an increased injection barrier
for holes, with a greater shift for Au/P3HT. These results demonstrate that
doping can drastically alter band alignment and the charge injection process at
metal/organic interfaces.Comment: 5 pages, 4 figure
Single crystal growth and physical properties of SrFe(AsP)
We report a crystal growth and physical properties of
SrFe(AsP). The single crystals for various s were
grown by a self flux method. For , reaches the maximum value of
30\,K and the electrical resistivity () shows -linear dependence.
As increases, decreases and () changes to -behavior,
indicating a standard Fermi liquid. These results suggest that a magnetic
quantum critical point exists around .Comment: 4 pages, 4 figures, accepted to Supplemental issue of the Journal of
Physical Society of Japan (JPSJ
Performance analysis with network-enhanced complexities: On fading measurements, event-triggered mechanisms, and cyber attacks
Copyright © 2014 Derui Ding et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Nowadays, the real-world systems are usually subject to various complexities such as parameter uncertainties, time-delays, and nonlinear disturbances. For networked systems, especially large-scale systems such as multiagent systems and systems over sensor networks, the complexities are inevitably enhanced in terms of their degrees or intensities because of the usage of the communication networks. Therefore, it would be interesting to (1) examine how this kind of network-enhanced complexities affects the control or filtering performance; and (2) develop some suitable approaches for controller/filter design problems. In this paper, we aim to survey some recent advances on the performance analysis and synthesis with three sorts of fashionable network-enhanced complexities, namely, fading measurements, event-triggered mechanisms, and attack behaviors of adversaries. First, these three kinds of complexities are introduced in detail according to their engineering backgrounds, dynamical characteristic, and modelling techniques. Then, the developments of the performance analysis and synthesis issues for various networked systems are systematically reviewed. Furthermore, some challenges are illustrated by using a thorough literature review and some possible future research directions are highlighted.This work was supported in part by the National Natural Science Foundation of China under Grants 61134009, 61329301, 61203139, 61374127, and 61374010, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany
Localized magnetic states in biased bilayer and trilayer graphene
We study the localized magnetic states of impurity in biased bilayer and
trilayer graphene. It is found that the magnetic boundary for bilayer and
trilayer graphene presents the mixing features of Dirac and conventional
fermion. For zero gate bias, as the impurity energy approaches the Dirac point,
the impurity magnetization region diminishes for bilayer and trilayer graphene.
When a gate bias is applied, the dependence of impurity magnetic states on the
impurity energy exhibits a different behavior for bilayer and trilayer graphene
due to the opening of a gap between the valence and the conduction band in the
bilayer graphene with the gate bias applied. The magnetic moment and the
corresponding magnetic transition of the impurity in bilayer graphene are also
investigated.Comment: 16 pages,6 figure
Superconducting gap symmetry of Ba0.6K0.4Fe2As2 studied by angle-resolved photoemission spectroscopy
We have performed high-resolution angle-resolved photoemission spectroscopy
on the optimally-doped BaKFeAs compound and determined
the accurate momentum dependence of the superconducting (SC) gap in four
Fermi-surface sheets including a newly discovered outer electron pocket at the
M point. The SC gap on this pocket is nearly isotropic and its magnitude is
comparable ( 11 meV) to that of the inner electron and hole
pockets (12 meV), although it is substantially larger than that of the
outer hole pocket (6 meV). The Fermi-surface dependence of the SC gap
value is basically consistent with () = coscos
formula expected for the extended s-wave symmetry. The observed finite
deviation from the simple formula suggests the importance of multi-orbital
effects.Comment: 4 pages, 3 figures, 1 tabl
Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors
The superconducting gap is the fundamental parameter that characterizes the
superconducting state, and its symmetry is a direct consequence of the
mechanism responsible for Cooper pairing. Here we discuss about angle-resolved
photoemission spectroscopy measurements of the superconducting gap in the
Fe-based high-temperature superconductors. We show that the superconducting gap
is Fermi surface dependent and nodeless with small anisotropy, or more
precisely, a function of momentum. We show that while this observation is
inconsistent with weak coupling approaches for superconductivity in these
materials, it is well supported by strong coupling models and global
superconducting gaps. We also suggest that the strong anisotropies measured by
other probes sensitive to the residual density of states are not related to the
pairing interaction itself, but rather emerge naturally from the smaller
lifetime of the superconducting Cooper pairs that is a direct consequence of
the momentum dependent interband scattering inherent to these materials.Comment: 7 pages, 5 figure
Dual Ginzburg-Landau Theory for Nonperturbative QCD
Nonperturbative QCD is studied with the dual Ginzburg-Landau theory, where
color confinement is realized through the dual Higgs mechanism by QCD-monopole
condensation. We obtain a general analytic formula for the string tension. A
compact formula is derived for the screened inter-quark potential in the
presence of light dynamical quarks. The QCD phase transition at finite
temperature is studied using the effective potential formalism. The string
tension and the QCD-monopole mass are largely reduced near the critical
temperature, . The surface tension is estimated from the effective
potential at . We propose also a new scenario of the quark-gluon-plasma
creation through the color-electric flux-tube annihilation. Finally, we discuss
a close relation between instantons and QCD-monopoles.Comment: Talk presented by H. Suganuma at the Int. Conf. ``CONFINEMENT95'',
March 22-24, 1995, Osaka, Japan, 12 pages, uses PHYZZ
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