1,401 research outputs found
Formation of an Icosahedral Structure during the Freezing of Gold Nanoclusters: Surface-Induced Mechanism
The freezing behavior of gold nanoclusters was studied by employing molecular
dynamics simulations based on a semi-empirical embedded-atom method.
Investigations of the gold nanoclusters revealed that, just after freezing,
ordered nano-surfaces with a fivefold symmetry were formed with interior atoms
remaining in the disordered state. Further lowering of temperatures induced
nano-crystallization of the interior atoms that proceeded from the surface
towards the core region, finally leading to an icosahedral structure. These
dynamic processes explain why the icosahedral cluster structure is dominantly
formed in spite of its energetic metastability.Comment: 9 pages, 4 figures(including 14 eps-files
Critical Level Statistics of the Fibonacci Model
We numerically analyze spectral properties of the Fibonacci model which is a
one-dimensional quasiperiodic system. We find that the energy levels of this
model have the distribution of the band widths obeys and , the gap
distribution () .
We also compare the results with those of multi-scale Cantor sets. We find
qualitative differences between the spectra of the Fibonacci model and the
multi-scale Cantor sets.Comment: 7 page
Photoemission Spectral Weight Transfer and Mass Renormalization in the Fermi-Liquid System LaSrTiO
We have performed a photoemission study of LaSrTiO near
the filling-control metal-insulator transition (MIT) as a function of hole
doping. Mass renormalization deduced from the spectral weight and the width of
the quasi-particle band around the chemical potential is compared with
that deduced from the electronic specific heat. The result implies that, near
the MIT, band narrowing occurs strongly in the vicinity of . Spectral
weight transfer occurs from the coherent to the incoherent parts upon
antiferromagnetic ordering, which we associate with the partial gap opening at
.Comment: 4 pages, 3 figure
Electron-Like Fermi Surface and Remnant (pi,0) Feature in Overdoped La1.78Sr0.22CuO4
We have performed an angle-resolved photoemission study of overdoped
La1.78Sr0.22CuO4, and have observed sharp nodal quasiparticle peaks in the
second Brillouin zone that are comparable to data from Bi2Sr2CaCu2O8+d. The
data analysis using energy distribution curves, momentum distribution curves
and intensity maps all show evidence of an electron-like Fermi surface, which
is well explained by band structure calculations. Evidence for many-body
effects are also found in the substantial spectral weight remaining below the
Fermi level around (pi,0), where the band is predicted to lie above EF.Comment: 4 pages, 4 figure
The Haldane-Rezayi Quantum Hall State and Magnetic Flux
We consider the general abelian background configurations for the
Haldane-Rezayi quantum Hall state. We determine the stable configurations to be
the ones with the spontaneous flux of with .
This gives the physical mechanism by which the edge theory of the state becomes
identical to the one for the 331 state. It also provides a new experimental
consequence which can be tested in the enigmatic plateau in a single
layer system.Comment: RevTex, 5 pages, 2 figures. v2:minor corrections. v4: published
version. Discussion on the thermodynamic limit adde
Theory of Electron Differentiation, Flat Dispersion and Pseudogap Phenomena
Aspects of electron critical differentiation are clarified in the proximity
of the Mott insulator. The flattening of the quasiparticle dispersion appears
around momenta and on square lattices and determines the
criticality of the metal-insulator transition with the suppressed coherence in
that momentum region of quasiparticles. Such coherence suppression at the same
time causes an instability to the superconducting state if a proper incoherent
process is retained. The d-wave pairing interaction is generated from such
retained processes without disturbance from the coherent single-particle
excitations. Pseudogap phenomena widely observed in the underdoped cuprates are
then naturally understood from the mode-mode coupling of d-wave
superconducting(dSC) fluctuations with antiferromagnetic ones. When we assume
the existence of a strong d-wave pairing force repulsively competing with
antiferromagnetic(AFM) fluctuations under the formation of flat and damped
single-particle dispersion, we reproduce basic properties of the pseudogap seen
in the magnetic resonance, neutron scattering, angle resolved photoemission and
tunneling measurements in the cuprates.Comment: 9 pages including 2 figures, to appear in J. Phys. Chem. Solid
One-dimensional metallic behavior of the stripe phase in LaSrCuO
Using an exact diagonalization method within the dynamical mean-field theory
we study stripe phases in the two-dimensional Hubbard model. We find a
crossover at doping from diagonal stripes to vertical
site-centered stripes with populated domain walls, stable in a broad range of
doping, . The calculated chemical potential shift and the doping dependence of the magnetic incommensurability are in
quantitative agreement with the experimental results for doped
LaSrCuO. The electronic structure shows one-dimensional
metallic behavior along the domain walls, and explains the suppression of
spectral weight along the Brillouin zone diagonal.Comment: 4 pages, 4 figure
- …