245 research outputs found
Positional Order and Diffusion Processes in Particle Systems
Nonequilibrium behaviors of positional order are discussed based on diffusion
processes in particle systems. With the cumulant expansion method up to the
second order, we obtain a relation between the positional order parameter
and the mean square displacement to be with a reciprocal vector and the dimension of the system .
On the basis of the relation, the behavior of positional order is predicted to
be when the system involves normal diffusion
with a diffusion constant . We also find that a diffusion process with
swapping positions of particles contributes to higher orders of the cumulants.
The swapping diffusion allows particle to diffuse without destroying the
positional order while the normal diffusion destroys it.Comment: 4 pages, 4 figures. Submitted to Phys. Rev.
Growth of Antiperovskite Oxide Ca3SnO Films by Pulsed Laser Deposition
We report the epitaxial growth of Ca3SnO antiperovskite oxide films on
(001)-oriented cubic yttria-stabilized zirconia (YSZ) substrates by using a
conventional pulsed laser deposition (PLD) technique. In this work, a sintered
Ca3SnO pellet is used as the ablation target. X-ray diffraction measurements
demonstrate the (001) growth of Ca3SnO films with the antiperovskite structure
and a cube-on-cube orientation relationship to the YSZ substrate. The
successful synthesis of the antiperovskite phase is further confirmed by x-ray
photoemission spectroscopy. These results strongly suggest that
antiperovskite-oxide films can be directly grown on substrates from the target
material using a PLD technique
Phase Structure of Four-dimensional Simplicial Quantum Gravity with a U(1) Gauge Field
The phase structure of four-dimensional simplicial quantum gravity coupled to
U(1) gauge fields has been studied using Monte-Carlo simulations. The smooth
phase is found in the intermediate region between the crumpled phase and the
branched polymer phase. This new phase has a negative string susceptibility
exponent, even if the number of vector fields (Nv) is 1. The phase transition
between the crumpled phase and the smooth phase has been studied by a finite
size scaling method. From the numerical results, we expect that this model
(coupled to one gauge field) has a higher order phase transition than first
order, which means the possibility to take the continuum limit at the critical
point. Furthermore, we consider a modification of the balls-in-boxes model for
a clear understanding of the relation between the numerical results and the
analytical one.Comment: 18 pages, latex, 6 figures, uses psfig.st
Salvage Surgery for Symptomatic Recurrence of Retro-Odontoid Pseudotumor after a C1 Laminectomy
We provide the first report of successful salvage surgery for a post-C1 laminectomy symptomatic recurrence of a retro-odontoid pseudotumor (ROP) that caused myelopathy. The 72-year-old Japanese woman presented with an ROP causing symptomatic cervical myelopathy. With ultrasonography support, we performed the enucleation of the ROP via a transdural approach and fusion surgery for the recurrence of the mass. At the final observation 2-year post-surgery, MRI demonstrated the mass’s regression and spinal cord decompression, and the patient’s symptoms had improved. Our strategy is an effective option for a symptomatic recurrence of ROP
A rejection-free Monte Carlo method for the hard-disk system
We construct a rejection-free Monte Carlo method for the hard-disk system.
Rejection-free Monte Carlo methods preserve the time-evolution behavior of the
standard Monte Carlo method, and this relationship is confirmed for our method
by observing nonequilibrium relaxation of a bond-orientational order parameter.
The rejection-free method gives a greater computational efficiency than the
standard method at high densities. The rejection free method is implemented in
a shrewd manner using optimization methods to calculate a rejection probability
and to update the system. This method should allow an efficient study of the
dynamics of two-dimensional solids at high density.Comment: 8 pages, 9 figures. This paper has been combined into the
cond-mat/0508652, and published in Phys. Rev.
Emergence of quantum critical behavior in metallic quantum-well states of strongly correlated oxides
Controlling quantum critical phenomena in strongly correlated electron
systems, which emerge in the neighborhood of a quantum phase transition, is a
major challenge in modern condensed matter physics. Quantum critical phenomena
are generated from the delicate balance between long-range order and its
quantum fluctuation. So far, the nature of quantum phase transitions has been
investigated by changing a limited number of external parameters such as
pressure and magnetic field. We propose a new approach for investigating
quantum criticality by changing the strength of quantum fluctuation that is
controlled by the dimensional crossover in metallic quantum well (QW)
structures of strongly correlated oxides. With reducing layer thickness to the
critical thickness of metal-insulator transition, crossover from a Fermi liquid
to a non-Fermi liquid has clearly been observed in the metallic QW of SrVO
by \textit{in situ} angle-resolved photoemission spectroscopy. Non-Fermi liquid
behavior with the critical exponent is found to emerge in the
two-dimensional limit of the metallic QW states, indicating that a quantum
critical point exists in the neighborhood of the thickness-dependent Mott
transition. These results suggest that artificial QW structures provide a
unique platform for investigating novel quantum phenomena in strongly
correlated oxides in a controllable fashion.Comment: 6 pages, 3 figure
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