15,365 research outputs found
Half-Skyrmions, Tensor Forces and Symmetry Energy in Cold Dense Matter
In a previous article, the 4D half-skyrmion (or 5D dyonic salt) structure of
dense baryonic matter described in crystalline configuration in the large
limit was shown to impact nontrivially on how anti-kaons behave in compressed
nuclear matter with a possible implication on an "ice-9" phenomenon of deeply
bound kaonic matter and condensed kaons in compact stars. We extend the
analysis to make a further prediction on the scaling properties of hadrons that
have a surprising effect on the nuclear tensor forces, the symmetry energy and
hence on the phase structure at high density. We treat this problem relying on
certain topological structure of chiral solitons. Combined with what can be
deduced from hidden local symmetry for hadrons in dense medium and the "soft"
dilatonic degree of freedom associated with the trace anomaly of QCD, we
uncover a novel structure of chiral symmetry in the "supersoft" symmetry energy
that can influence the structure of neutron stars.Comment: 8 pages, 4 figures; contents unchanged but expanded for a journa
Rotating Black Hole Entropy from Two Different Viewpoints
Using the brick-wall method, we study the entropy of Kerr-Newman black hole
from two different viewpoints, a rest observer at infinity and zero angular
momentum observer near horizon. We investigate this with scalar field in the
canonical quantization approach. An observer at infinity can take one of the
two possible frequency ranges; one is with positive frequencies only and the
other is with the whole range including negative frequencies. On the other
hand, a zero angular momentum observer near horizon can take positive
frequencies only. For the observer at infinity the superradiant modes appear in
either choice of the frequency ranges and the two results coincide. For the
zero angular momentum observer superradiant modes do not appear due to absence
of ergoregion. The resulting entropies from the two viewpoints turn out to be
the same.Comment: LaTeX 18 pages, 2 figures, Minor modifications in section 3(ZAMO
Giant Flexoelectric Effect in Ferroelectric Epitaxial Thin Films
We report on nanoscale strain gradients in ferroelectric HoMnO3 epitaxial
thin films, resulting in a giant flexoelectric effect. Using grazing-incidence
in-plane X-ray diffraction, we measured strain gradients in the films, which
were 6 or 7 orders of magnitude larger than typical values reported for bulk
oxides. The combination of transmission electron microscopy, electrical
measurements, and electrostatic calculations showed that flexoelectricity
provides a means of tuning the physical properties of ferroelectric epitaxial
thin films, such as domain configurations and hysteresis curves.Comment: Accepted by Phys. Rev. Let
Putative spin liquid in the triangle-based iridate BaIrTiO
We report on thermodynamic, magnetization, and muon spin relaxation
measurements of the strong spin-orbit coupled iridate BaIrTiO,
which constitutes a new frustration motif made up a mixture of edge- and
corner-sharing triangles. In spite of strong antiferromagnetic exchange
interaction of the order of 100~K, we find no hint for long-range magnetic
order down to 23 mK. The magnetic specific heat data unveil the -linear and
-squared dependences at low temperatures below 1~K. At the respective
temperatures, the zero-field muon spin relaxation features a persistent spin
dynamics, indicative of unconventional low-energy excitations. A comparison to
the isostructural compound BaRuTiO suggests that a concerted
interplay of compass-like magnetic interactions and frustrated geometry
promotes a dynamically fluctuating state in a triangle-based iridate.Comment: Physical Review B accepte
1-{2-[(Anthracen-10-yl)methyleneamino]phenyl}-3-phenylthiourea
The title compound, C28H21N3S, crystallizes with two molecules in the asymmetric unit. There are only very slight differences in the torsion angles between the two molecules. The two molecules are stabilized by intramolecular N—H⋯N interactions and the crystal packing is stabilized by intermolecular N—H⋯S interactions
Double polarization hysteresis loop induced by the domain pinning by defect dipoles in HoMnO3 epitaxial thin films
We report on antiferroelectriclike double polarization hysteresis loops in
multiferroic HoMnO3 thin films below the ferroelectric Curie temperature. This
intriguing phenomenon is attributed to the domain pinning by defect dipoles
which were introduced unintentionally during film growth process. Electron
paramagnetic resonance suggests the existence of Fe1+ defects in thin films and
first principles calculations reveal that the defect dipoles would be composed
of oxygen vacancy and Fe1+ defect. We discuss migration of charged point
defects during film growth process and formation of defect dipoles along
ferroelectric polarization direction, based on the site preference of point
defects. Due to a high-temperature low-symmetry structure of HoMnO3, aging is
not required to form the defect dipoles in contrast to other ferroelectrics
(e.g., BaTiO3).Comment: 4 figure
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