36,550 research outputs found
Colored Ray Configurations
We study the cyclic sequences induced at infinity by pairwise-disjoint colored rays with apices on a given balanced
bichromatic point set, where the color of a ray is
inherited from the color of its apex. We derive a lower bound on the number of color sequences that can be realized from any fixed point set. We also examine sequences
that can be realized regardless of the point set and exhibit negative examples as well. In addition, we provide algorithms to decide whether a sequence is realizable from a given point set on a line or in convex position
High-spin states with seniority v=4,4,6 in 119-126Sn
The 119-126Sn nuclei have been produced as fission fragments in two reactions
induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85
MeV. Their level schemes have been built from gamma rays detected using the
Euroball array. High-spin states located above the long-lived isomeric states
of the even- and odd-A 120-126Sn nuclei have been identified. Moreover isomeric
states lying around 4.5 MeV have been established in 120,122,124,126Sn from the
delayed coincidences between the fission fragment detector SAPhIR and the
Euroball array. The states located above 3-MeV excitation energy are ascribed
to several broken pairs of neutrons occupying the nu h11/2 orbit. The maximum
value of angular momentum available in such a high-j shell, i.e. for
mid-occupation and the breaking of the three neutron pairs, has been
identified. This process is observed for the first time in spherical nuclei.Comment: 20 pages, 22 figures, 12 tables, accepted for publication in Physical
Review
Effect of isoelectronic doping on honeycomb lattice iridate A_2IrO_3
We have investigated experimentally and theoretically the series
(NaLi)IrO. Contrary to what has been believed so far,
only for the system forms uniform solid solutions. For larger Li
content, as evidenced by powder X-ray diffraction, scanning electron microscopy
and density functional theory calculations, the system shows a miscibility gap
and a phase separation into an ordered NaLiIrO phase with
alternating Na and LiIrO planes, and a Li-rich phase close to pure
LiIrO. For we observe (1) an increase of with Li
doping up to , despite the fact that in pure LiIrO is
smaller than in NaIrO, and (2) a gradual reduction of the
antiferromagnetic ordering temperature and ordered moment. The
previously proposed magnetic quantum phase transition at may
occur in a multiphase region and its nature needs to be re-evaluated.Comment: 8 pages, 9 figures including supplemental informatio
Mapping the Gas Turbulence in the Coma Cluster: Predictions for Astro-H
Astro-H will be able for the first time to map gas velocities and detect
turbulence in galaxy clusters. One of the best targets for turbulence studies
is the Coma cluster, due to its proximity, absence of a cool core, and lack of
a central active galactic nucleus. To determine what constraints Astro-H will
be able to place on the Coma velocity field, we construct simulated maps of the
projected gas velocity and compute the second-order structure function, an
analog of the velocity power spectrum. We vary the injection scale, dissipation
scale, slope, and normalization of the turbulent power spectrum, and apply
measurement errors and finite sampling to the velocity field. We find that even
with sparse coverage of the cluster, Astro-H will be able to measure the Mach
number and the injection scale of the turbulent power spectrum--the quantities
determining the energy flux down the turbulent cascade and the diffusion rate
for everything that is advected by the gas (metals, cosmic rays, etc.). Astro-H
will not be sensitive to the dissipation scale or the slope of the power
spectrum in its inertial range, unless they are outside physically motivated
intervals. We give the expected confidence intervals for the injection scale
and the normalization of the power spectrum for a number of possible pointing
configurations, combining the structure function and velocity dispersion data.
Importantly, we also determine that measurement errors on the line shift will
bias the velocity structure function upward, and show how to correct this bias.Comment: 18 pages, 13 figures. Matches published ApJ version, except that it
fixes an error in the left panel of Figure 5 that is being addressed in an
ApJ erratu
Strain-gradient-induced magnetic anisotropy in straight-stripe mixed-phase bismuth ferrites: An insight into flexomagnetic phenomenon
Implementation of antiferromagnetic compounds as active elements in
spintronics has been hindered by their insensitive nature against external
perturbations which causes difficulties in switching among different
antiferromagnetic spin configurations. Electrically-controllable strain
gradient can become a key parameter to tune the antiferromagnetic states of
multiferroic materials. We have discovered a correlation between an
electrically-written straight-stripe mixed-phase boundary and an in-plane
antiferromagnetic spin axis in highly-elongated La-5%-doped BiFeO thin
films by performing polarization-dependent photoemission electron microscopy in
conjunction with cluster model calculations. Model Hamiltonian calculation for
the single-ion anisotropy including the spin-orbit interaction has been
performed to figure out the physical origin of the link between the strain
gradient present in the mixed phase area and its antiferromagnetic spin axis.
Our findings enable estimation of the strain-gradient-induced magnetic
anisotropy energy per Fe ion at around 510 eV m, and provide a
new pathway towards an electric-field-induced 90 rotation of
antiferromagnetic spin axis at room temperature by flexomagnetism.Comment: 32 pages, 5 figure
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