2,860 research outputs found
Cooper-Pair Spin Current in a Strontium Ruthenate Heterostructure
It has been recognized that the condensation of spin-triplet Cooper pairs
requires not only the broken gauge symmetry but also the spin ordering as well.
One consequence of this is the possibility of the Cooper-pair spin current
analogous to the magnon spin current in magnetic insulators, the analogy also
extending to the existence of the Gilbert damping of the collective
spin-triplet dynamics. The recently fabricated heterostructure of the thin film
of the itinerant ferromagnet SrRuO3 on the bulk Sr2RuO4, the best-known
candidate material for the spin-triplet superconductor, offers a promising
platform for generating such spin current. We will show how such
heterostructure allows us to not only realize the long-range spin valve but
also electrically drive the collective spin mode of the spin-triplet order
parameter. Our proposal represents both a new realization of the spin
superfluidity and a transport signature of the spin-triplet superconductivity.Comment: 5 pages, 3 figure
Magnon topology and thermal Hall effect in trimerized triangular lattice antiferromagnet
The non-trivial magnon band topology and its consequent responses have been
extensively studied in two-dimensional magnetisms. However, the triangular
lattice antiferromagnet (TLAF), the best-known frustrated two-dimensional
magnet, has received less attention than the closely related Kagome system,
because of the spin-chirality cancellation in the umbrella ground state of the
undistorted TLAF. In this work, we study the band topology and the thermal Hall
effect (THE) of the TLAF with (anti-)trimerization distortion under the
external perpendicular magnetic field using the linearized spin wave theory. We
show that the spin-chirality cancellation is removed in such case, giving rise
to the non-trivial magnon band topology and the finite THE. Moreover, the
magnon bands exhibit band topology transitions tuned by the magnetic field. We
demonstrate that such transitions are accompanied by the logarithmic divergence
of the first derivative of the thermal Hall conductivity. Finally, we examine
the above consequences by calculating the THE in the hexagonal manganite
YMnO, well known to have anti-trimerization.Comment: 6 + 7 pages, 3 + 5 figures, 0 + 1 table; Journal reference adde
Protein Fractions from Korean Mistletoe ( Viscum Album coloratum
Mistletoe (Viscum Album coloratum) has been known as a medicinal plant in European and Asian countries. Recent data show that biological activity of mistletoe alleviates hypertension, heart disease, renal failure, and cancer development. In this study, we report the antidiabetic effect of Korean mistletoe extract (KME). KME treatments enhanced the insulin secretion from the pancreatic ฮฒ-cell without any effects of cytotoxicity. PDX-1 and beta2/neuroD known as transcription factors that regulate the expression of insulin gene were upregulated by treatment of the KME protein fractions isolated by ion-exchange chromatography after ammonium sulfate precipitation. Furthermore, these KME protein fractions significantly lowered the blood glucose level and the volume of drinking water in alloxan induced hyperglycemic mice. Taken together with the findings, it provides new insight that KME might be served as a useful source for the development of medicinal reagent to reduce blood glucose level of type I diabetic patients
Orbital selective Fermi surface shifts and mechanism of high T superconductivity in correlated AFeAs (A=Li,Na)
Based on the dynamical mean field theory (DMFT) and angle resolved
photoemission spectroscopy (ARPES), we have investigated the mechanism of high
superconductivity in stoichiometric LiFeAs. The calculated spectrum is in
excellent agreement with the observed ARPES measurement. The Fermi surface (FS)
nesting, which is predicted in the conventional density functional theory
method, is suppressed due to the orbital-dependent correlation effect with the
DMFT method. We have shown that such marginal breakdown of the FS nesting is an
essential condition to the spin-fluctuation mediated superconductivity, while
the good FS nesting in NaFeAs induces a spin density wave ground state. Our
results indicate that fully charge self-consistent description of the
correlation effect is crucial in the description of the FS nesting-driven
instabilities.Comment: 5 pages, 4 figures, supporting informatio
Two-dimensional charge distributions of the baryon: Interpolation between the nonrelativistic and ultrarelativistic limit
We investigate how the charge distributions of both the unpolarized and
transversely polarized baryon change as the longitudinal
momentum~() of the baryon increases from to
in a Wigner phase-space perspective. When the baryon is
longitudinally polarized, its two-dimensional charge distribution is kept to be
spherically symmetric with varied, whereas when the baryon is
transversely polarized along the -axis, the quadrupole contribution emerges
at the rest frame (). When grows, the electric dipole and
octupole moments are induced. The induced dipole moment dominates over other
higher multipole contributions and governs the deformation of the charge
distribution of the baryon.Comment: 22 pages, 12 figure
Instanton effects on electromagnetic transitions of charmonia
We investigate the mass spectrum and electromagnetic transitions of
charmonia, emphasizing the instanton effects on them. The heavy-quark potential
consists of the Coulomb-like potential from one-gluon exchange and the linear
confining potential. We introduce the nonperturbative heavy-quark potential
derived from the instanton vacuum. We also consider the screened confining
potential, which better describes the electromagnetic decays of higher excited
states. Using this improved heavy-quark potential, we compute the mass spectrum
and electromagnetic decays of the charmonia. Focusing on the instanton effects,
we discuss the results compared with the experimental data and those from other
works. The instanton effects are marginal on the electromagnetic decays of
charmonia.Comment: 10 pages and 4 figures. The final version to be published in Progress
of Theoretical and Experimental Physic
Energy-Efficient Region Shift Scheme to Support Mobile Sink Group in Wireless Sensor Networks.
Mobile sink groups play crucial roles to perform their own missions in many wireless sensor network (WSN) applications. In order to support mobility of such sink groups, it is important to design a mechanism for effective discovery of the group in motion. However, earlier studies obtain group region information by periodic query. For that reason, the mechanism leads to significant signaling overhead due to frequent flooding for the query regardless of the group movement. Furthermore, the mechanism worsens the problem by the flooding in the whole expected area. To deal with this problem, we propose a novel mobile sink group support scheme with low communication cost, called Region-Shift-based Mobile Geocasting Protocol (RSMGP). In this study, we utilize the group mobility feature for which members of a group have joint motion patterns. Thus, we could trace group movement by shifting the region as much as partial members move out of the previous region. Furthermore, the region acquisition is only performed at the moment by just deviated members without collaboration of all members. Experimental results validate the improved signaling overhead of our study compared to the previous studies
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