14,775 research outputs found
Interplay between different states in heavy fermion physics
Calorimetry experiments under high pressure were used to clarify the
interplay between different states such as superconductivity and
antiferromagnetism in CeRhIn5, spin density wave and large moment
antiferromagnetism in URu2Si2. Evidences are given on the re-entrance of
antiferromagnetism under magnetic field in the superconducting phase of CeRhIn5
up to pc = 2.5 GPa where the Neel temperature will collapse in the absence of
superconductivity. For URu2Si2 measurements up to 10 GPa support strongly the
coexistence of spin density wave and large moment antiferromagnetism at high
pressures.Comment: 6 pages, 9 figures, presented at ICM200
Manifestation of spin degrees of freedom in the double fractional quantum Hall system
The double fractional quantum Hall system of spin 1/2 electrons is
numerically studied to predict that there exists a novel spin-unpolarized
quantum liquid specific to the multi-species system, which exemplifies a link
between the spin state and the inter-layer electron correlation. Even when the
ground state is spin-polarized, the lowest charge-excitation mode involves the
spin when the interlayer tunneling is considered.Comment: typeset in LATEX, 2 figures available upon request at
[email protected], 9 pages, NA-94-0
Investigation of environmental change pattern in Japan. Investigation of the ecological environment index from observation of the regional vegetation cover and their growing condition
There are no author-identified significant results in this report
Spin-squeezed Ground States in the Bilayer Quantum Hall Ferromagnet
A "squeezed-vacuum" state considered in quantum optics is shown to be
realized in the ground-state wavefunction for the bilayer quantum Hall system
at the total Landau level filling of (m: odd integer). This is
derived in the boson approximation, where a particle-hole pair creation across
the symmetric-antisymmetric gap, , is regarded as a boson. In
terms of the pseudospin describing the layers, the state is a spin-squeezed
state, where the degree of squeezing is controlled by the layer separation and
. An exciton condensation, which amounts to a rotated
spin-squeezed state, has a higher energy due to the degraded SU(2) symmetry for
.Comment: 4 pages, revtex, one figure, to appear in PRB Rapid Communicatio
Superconductivity at T_c ~ 14 K in Single Crystalline FeTeSe
Single crystalline FeTeSe with a sharp superconducting
transition at 14 K is synthesized via slow furnace
cooling followed by low-temperature annealing. The effect of annealing on the
chemical and superconducting inhomogeneities is carefully characterized. We
also report resistivity, magnetization, and magneto-optical images of this
crystal. Based on the Bean model, critical current density is estimated to
exceed A/cm below 5 K under zero field. Weak fish-tail
effect is identified at lower temperatures.Comment: 4 pages, 4 figure
Very Fast Chip-level Thermal Analysis
We present a new technique of VLSI chip-level thermal analysis. We extend a
newly developed method of solving two dimensional Laplace equations to thermal
analysis of four adjacent materials on a mother board. We implement our
technique in C and compare its performance to that of a commercial CAD tool.
Our experimental results show that our program runs 5.8 and 8.9 times faster
while keeping smaller residuals by 5 and 1 order of magnitude, respectively.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Thermodynamic Construction of an One-Step Replica-Symmetry-Breaking Solution in Finite Connectivity Spin Glasses
An one-step replica-symmetry-breaking solution for finite connectivity
spin-glass models with K body interaction is constructed at finite temperature
using the replica method and thermodynamic constraints. In the absence of
external fields, this construction provides a general extension of replica
symmetric solution at finite replica number to one-step
replica-symmetry-breaking solution. It is found that this result is formally
equivalent to that of the one-step replica-symmetry-breaking cavity method. To
confirm the validity of the obtained solution, Monte Carlo simulations are
performed for K = 2 and 3. The thermodynamic quantities of the Monte Carlo
results extrapolated to a large-size limit are consistent with those estimated
by our solution for K = 2 at all simulated temperatures and for K = 3 except
near the transition temperature.Comment: 11pages, 19 figures. Added content and references. Accepted to Phys.
Rev.
A-site Randomness Effect on Structural and Physical Properties of Ba-based Perovskite Manganites
The discovery of novel structural and physical properties in the -site
ordered manganite BaMnO ( = Y and rare earth elements) has
demanded new comprehension about perovskite manganese oxides. In the present
study, the -site disordered form, BaMnO, has been
investigated and compared with both BaMnO and
MnO (: Sr, Ca) in the structures and electromagnetic
properties. BaMnO has a primitive cubic perovskite cell
in the structure and magnetic glassy states are dominant as its ground state,
in contrast to the ordinary disordered MnO (: Sr, Ca).
In Pr-compounds with various degrees of Pr/Ba randomness at the -sites, the
-site disorder gradually suppresses both ferromagnetic and A-type
antiferromagnetic transitions and finally leads to a magnetic glassy state in
PrBaMnO. A peculiar behavior, multi-step magnetization
and resistivity change, has been observed in PrBaMnO.
These properties could be closely related to any spatial heterogeneity caused
by the random distribution of Ba and with much different
ionic radius.Comment: 9 pages, to be published in J. Phys. Soc. Jpn. 73 Aug. (2004
Coexistence of ferromagnetism and superconductivity near quantum phase transition: The Heisenberg- to Ising-type crossover
A microscopic mean-field theory of the phase coexistence between
ferromagnetism and superconductivity in the weakly ferromagnetic itinerant
electron system is constructed, while incorporating a realistic mechanism for
superconducting pairing due to the exchange of critical spin fluctuations. The
self-consistent solution of the resulting equations determines the
superconducting transition temperature which is shown to depend strongly on the
exchange splitting. The effect of phase crossover from isotropic
(Heisenberg-like) to uniaxial (Ising-like) spin fluctuations near the quantum
phase transition is analysed and the generic phase diagram is obtained. This
scenario is then applied to the case of itinerant ferromagnet ZrZn2, which
sheds light on the proposed phase diagram of this compound. Possible
explanation of superconductivity in UGe2 is also discussed.Comment: 5 pages, 3 figure
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