12,485 research outputs found
First-principles study of the relaxor ferroelectricity of Ba(Zr,Ti)O
Ba(Zr,Ti)O is a lead-free relaxor ferroelectric. Using the
first-principles method, the ferroelectric dipole moments for pure BaTiO
and Ba(Zr,Ti)O supercells have been studied. All possible ion
configurations of BaZrTiO and BaZrTiO
are constructed in a supercell. For the half-substituted
case, divergence of ferroelectric properties has been found among these
structures, which seriously depends on the arrangement of Ti and Zr ions. Thus
our results provide a reasonable explanation to the relaxor behavior of
Ba(Zr,Ti)O. In addition, a model based on the thermal statistics gives the
averaged polarization for Ba(Zr,Ti)O, which depends on the temperature of
synthesis. Our result is helpful to understand and tune the relaxor
ferroelectricity of lead-free Ba(Zr,Ti)O.Comment: 15 pages, 2 figures, 2 table
Search for via associated production at LHC
Many new physics models predict the existence of extra neutral gauge bosons
(). Inspired by the recent development on Higgs search, we study the
properties of via the Higgs and boson associated production. The
couplings of to quarks can be investigated through process, which also provides extraordinary signal for
understanding the properties of interaction. The standard model
background processes can be significantly suppressed by adopting appropriate
kinematic cuts. The charged lepton angular distributions are related to the
ratio of chiral couplings of to quarks via interaction
Singlet -wave pairing in quasi-one-dimensional ACrAs (A=K, Rb, Cs) superconductors
The recent discovery of quasi-one-dimensional Chromium-based
superconductivity has generated much excitement. We study in this work the
superconducting instabilities of a representative compound, the newly
synthesized KCrAs superconductor. Based on inputs from density
functional theory calculations, we first construct an effective multi-orbital
tight-binding Hamiltonian to model its low-energy band structure. We then
employ standard random-phase approximation calculations to investigate the
superconducting instabilities of the resultant multi-orbital Hubbard model. We
find various pairing symmetries in the phase diagram in different interaction
parameter regimes, including the triplet -wave, -wave and singlet
-wave pairings. We argue that the singlet -wave pairing, which
emerges at intermediate interaction strength, is realized in this material.
This singlet pairing is driven by spin-density wave fluctuations enhanced by
Fermi-surface nesting. We point out that phase-sensitive measurement can
distinguish the -wave pairing in KCrAs from the -wave
previously proposed for a related compound KCrAs. The
-wave pairing in KCrAs shall also exhibit a subgap spin
resonance mode near the nesting vector, which can be tested by inelastic
neutron scattering measurements. Another intriguing property of the
-pairing is that it can induce time-reversal invariant topological
superconductivity in a semiconductor wire with large Rashba spin-orbit coupling
via proximity effect. Our study shall be of general relevance to all
superconductors in the family of ACrAs (A=K, Rb, Cs)
How to Write High-quality News on Social Network? Predicting News Quality by Mining Writing Style
Rapid development of Internet technologies promotes traditional newspapers to
report news on social networks. However, people on social networks may have
different needs which naturally arises the question: whether can we analyze the
influence of writing style on news quality automatically and assist writers in
improving news quality? It's challenging due to writing style and 'quality' are
hard to measure. First, we use 'popularity' as the measure of 'quality'. It is
natural on social networks but brings new problems: popularity are also
influenced by event and publisher. So we design two methods to alleviate their
influence. Then, we proposed eight types of linguistic features (53 features in
all) according eight writing guidelines and analyze their relationship with
news quality. The experimental results show these linguistic features influence
greatly on news quality. Based on it, we design a news quality assessment model
on social network (SNQAM). SNQAM performs excellently on predicting quality,
presenting interpretable quality score and giving accessible suggestions on how
to improve it according to writing guidelines we referred to.Comment: 7 pages, 6 figure
High Spatial Resolution Spectroscopy of G292.0+1.8 with Chandra
We present high spatial resolution X-ray spectroscopy of supernova remnant
G292.0+1.8 with the {\sl Chandra} observations. The X-ray emitting region of
this remnant was divided into 25 25 pixels with a scale of 20\arcsec
20\arcsec each. Spectra of 324 pixels were created and fitted with
an absorbed one component non-equilibrium ionization model. With the spectral
analysis results we obtained maps of absorbing column density, temperature,
ionization age, and the abundances for O, Ne, Mg, Si, S, and Fe. The abundances
of O, Ne and Mg show tight correlations between each other in the range of
about two orders of magnitude, suggesting them all from explosive C/Ne burning.
Meanwhile, the abundances of Si and S are also well correlated, indicating them
to be the ashes of explosive explosive O-burning or incomplete Si-burbing. The
Fe emission lines are not prominent among the whole remnant, and its abundance
are significantly deduced, indicating that the reverse shock may have not
propagated to the Fe-rich ejecta. Based on relative abundances of O, Ne, Mg, Si
and Fe to Si, we suggest a progenitor mass of for this
remnant.Comment: accepted by RA
Strain driven sequential magnetic transitions in strained GdTiO3 on compressive substrates: a first-principles study
The compressive strain effects on the magnetic ground state and electronic
structure of strained GdTiO 3 have been studied by the first-principles method.
Different from the congeneric YTiO3 and LaTiO3 cases both of which becomes the
A-type antiferromagnetism on the (001) LaAlO3 substrate despite their
contrastive magnetism, the ground state of strained GdTiO3 on the LaAlO3
substrate changes from the original ferromagnetism to G-type antiferromagnetim,
instead of the A-type one although Gd 3+ is between Y3+ and La3+. Only when the
in-plane compressive strain is large enough, e.g. on the (001) YAlO3 substrate,
the ground state finally becomes the A-type one. The band structure calculation
shows that these compressive strained GdTiO3 remain insulating, although the
band gap changes a little in these strained GdTiO3.Comment: 18 pages, 5 figures, 3 table
Search for signal in single top quark production at LHC
The heavy charged gauge bosons were proposed in the theories beyond standard
model. We explore the discovery potential for with top quark
semi-leptonic decay at the LHC. We concentrate on the new physics signal search
with the deviation from the standard model prediction if the resonance peak of
can not be observed directly. The events of signal with two jets plus one
charged lepton and missing energy are simulated together with the dominant
standard model backgrounds. In this paper, it is found that suitable cuts on
the kinematic observables can effectively suppress the standard model
backgrounds, so that it is possible to search for signal at the LHC with
its mass less than 6.6 TeV.Comment: 20 pages, 14 figure
Szegedy Quantum Walks with Memory on Regular Graphs
Quantum walks with memory(QWM) are a type of modified quantum walks that
record the walker's latest path. The general model of coined QWM is presented
in Phys. Rev. A 93, 042323 (2016). In this paper, we present general model of
Szegedy QWM. Importantly, the relation of coined QWM and Szegedy QWM is
revealed. By transforming coined QWM to Szegedy QWM, some amazing results about
QWM are founded.Comment: 6 pages, 8 figure
Controlled Alternate Quantum Walks based Quantum Hash Function
Through introducing controlled alternative quantum walks, we present
controlled alternate quantum walks (CAQW) based quantum hash function. CAQW
based quantum hash function have excellent security, outstanding statistical
performance and splendid expansibility. Furthermore, due to the structure of
alternative quantum walks, implementing CAQW based quantum hash function
significantly reduces the resources necessary for its feasible experimental
realization than implementing other quantum hash functions. Besides, CAQW based
quantum hash function has expansibility
Poly[μ-aqua-di-μ-benzoato-lead(II)]
The reaction of lead(II) nitrate and benzoic acid in aqueous solution yields the title polymer, [Pb(C7H5O2)2(H2O)]n. The asymmetric unit contains one PbII ion, two benzoate ligands and one water molÂecule. The Pb—O bond distances are in the range 2.494 (4)–2.735 (4) Å. The Pb⋯Pb distance is 4.0683 (4) Å, indicating an insignificant metal–metal interÂaction. The PbII atom has a distorted pentaÂgonal-bipyramidal geometry chelated by two carboxylÂate O atoms. The Pb atoms are bridged through a coordinating water molÂecule and two carboxylÂate O atoms from another two benzoate ligands, giving an infinite three-dimensional supraÂmolecular structure. O—H⋯O hydrogen-bonding interÂactions involved the coordinating water and carboxylÂate O atoms enhance the stability of the supraÂmolecular arrangement
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