51,466 research outputs found
Aging dynamics of ferromagnetic and reentrant spin glass phases in stage-2 CuCCl graphite intercalation compound
Aging dynamics of a reentrant ferromagnet stage-2
CuCoCl graphite intercalation compound has been studied
using DC magnetic susceptibility. This compound undergoes successive
transitions at the transition temperatures ( K) and
( K). The relaxation rate exhibits a
characteristic peak at below . The peak time as a
function of temperature shows a local maximum around 5.5 K, reflecting a
frustrated nature of the ferromagnetic phase. It drastically increases with
decreasing temperature below . The spin configuration imprinted at the
stop and wait process at a stop temperature () during the
field-cooled aging protocol, becomes frozen on further cooling. On reheating,
the memory of the aging at is retrieved as an anomaly of the
thermoremnant magnetization at . These results indicate the occurrence
of the aging phenomena in the ferromagnetic phase () as well
as in the reentrant spin glass phase ().Comment: 9 pages, 9 figures; submitted to Physical Review
p-Wave superfluid and phase separation in atomic Bose-Fermi mixture
We consider a system of repulsively interacting Bose-Fermi mixtures of spin
polarized uniform atomic gases at zero temperature. We examine possible
realization of p-wave superfluidity of fermions due to an effective attractive
interaction via density fluctuations of Bose-Einstein condensate within
mean-field approximation. We find the ground state of the system by direct
energy comparison of p-wave superfluid and phase-separated states, and suggest
an occurrence of the p-wave superfluid for a strong boson-fermion interaction
regime. We study some signatures in the p-wave superfluid phase, such as
anisotropic energy gap and quasi-particle energy in the axial state, that have
not been observed in spin unpolarized superfluid of atomic fermions. We also
show that a Cooper pair is a tightly bound state like a diatomic molecule in
the strong boson-fermion coupling regime and suggest an observable indication
of the p-wave superfluid in the real experiment.Comment: 7 pages, 6 figur
Is really related to the solar neutrino solutions?
It has been said that the measurements of in the lepton flavor
mixing matrix would help discriminate between the possible solar neutrino
solutions under the natural conditions with the neutrino mass hierarchies of
and , where is the -th
generation neutrino absolute mass. However, it is not true, and the relation
between and obtained by Akhmedov, Branco, and
Rebelo is trivial in actual. We show in this paper that the value of
cannot predict the solar neutrino solutions without one additional nontrivial
condition.Comment: 7pages, no figur
Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow.
The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics
Flow Representation of the Bose-Hubbard Hamiltonian : General Case
In this paper the explicit flow representation to the Bose-Hubbard
Hamiltonian is given in the general case. This representation may be useful in
creating cat states for the system of atoms trapped in the optical ring.Comment: Latex ; 8 pages ; 1 figure ; minor change
Extrapolation-CAM Theory for Critical Exponents
By intentionally underestimating the rate of convergence of
exact-diagonalization values for the mass or energy gaps of finite systems, we
form families of sequences of gap estimates. The gap estimates cross zero with
generically nonzero linear terms in their Taylor expansions, so that
for each member of these sequences of estimates. Thus, the Coherent Anomaly
Method can be used to determine . Our freedom in deciding exactly how to
underestimate the convergence allows us to choose the sequence that displays
the clearest coherent anomaly. We demonstrate this approach on the
two-dimensional ferromagnetic Ising model, for which . We also use it
on the three-dimensional ferromagnetic Ising model, finding , in good agreement with other estimates.Comment: 21 pages, Submitted to Journal of Physics A; new section added
discussing rate of convergence and relation to Finite-Size Scalin
Dynamics of the superfluid to Mott insulator transition in one dimension
We numerically study the superfluid to Mott insulator transition for bosonic
atoms in a one dimensional lattice by exploiting a recently developed
simulation method for strongly correlated systems. We demonstrate this methods
accuracy and applicability to Bose-Hubbard model calculations by comparison
with exact results for small systems. By utilizing the efficient scaling of
this algorithm we then concentrate on systems of comparable size to those
studied in experiments and in the presence of a magnetic trap. We investigate
spatial correlations and fluctuations of the ground state as well as the nature
and speed at which the superfluid component is built up when dynamically
melting a Mott insulating state by ramping down the lattice potential. This is
performed for slow ramping, where we find that the superfluid builds up on a
time scale consistent with single-atom hopping and for rapid ramping where the
buildup is much faster than can be explained by this simple mechanism. Our
calculations are in remarkable agreement with the experimental results obtained
by Greiner et al. [Nature (London) 415, 39 (2002)].Comment: 14 pages, 11 figures, RevTex 4. Replaced with published versio
Effect of random disorder and spin frustration on the reentrant spin glass phase and ferromagnetic phase in stage-2 Cu_{0.93}Co_{0.07}Cl_{2} graphite intercalation compound near the multicritical point
Stage-2 CuCoCl graphite intercalation compound
magnetically behaves like a reentrant ferromagnet near the multicritical point
(). It undergoes two magnetic phase transitions at
( K) and ( K). The static
and dynamic nature of the ferromagnetic and reentrant spin glass phase has been
studied using DC and AC magnetic susceptibility. Characteristic memory
phenomena of the DC susceptibility are observed at and . The
nonlinear AC susceptibility has a positive local maximum at
, and a negative local minimum at . The relaxation time
between and shows a critical slowing down: with and sec. The
influence of the random disorder on the critical behavior above is
clearly observed: , , and . The
exponent of is far from that of 3D Heisenberg model.Comment: 15 pages, 16 figures, submitted to Phys. Rev.
Clustering of Far-Infrared Galaxies in the AKARI All-Sky Survey
We present the first measurement of the angular two-point correlation
function for AKARI 90-m point sources, detected outside of the Milky Way
plane and other regions characterized by high Galactic extinction, and
categorized as extragalactic sources according to our far-infrared-color based
criterion (Pollo et al. 2010). This is the first measurement of the large-scale
angular clustering of galaxies selected in the far-infrared after IRAS
measurements. Although a full description of clustering properties of these
galaxies will be obtained by more detailed studies, using either spatial
correlation function, or better information about properties and at least
photometric redshifts of these galaxies, the angular correlation function
remains the first diagnostics to establish the clustering properties of the
catalog and observed galaxy population. We find a non-zero clustering signal in
both hemispheres extending up to degrees, without any significant
fluctuations at larger scales. The observed correlation function is well fitted
by a power law function. The notable differences between a northern and
southern hemisphere are found, which can be probably attributed to the
photometry problems and point out to a necessity of performing a better
calibration in the data from southern hemisphere.Comment: 6 pages, 6 figures, accepted for publication in Earth, Planets, and
Spac
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