10,431 research outputs found
Gutzwiller study of extended Hubbard models with fixed boson densities
We studied all possible ground states, including supersolid (SS) phases and
phase separations of hard-core- and soft-core-extended Bose--Hubbard models
with fixed boson densities by using the Gutzwiller variational wave function
and the linear programming method. We found that the phase diagram of the
soft-core model depends strongly on its transfer integral. Furthermore, for a
large transfer integral, we showed that an SS phase can be the ground state
even below or at half filling against the phase separation. We also found that
the density difference between nearest-neighbor sites, which indicates the
density order of the SS phase, depends strongly on the boson density and
transfer integral.Comment: 14 pages, 14 figures, to be published in Phys. Rev.
Test evaluation of fuel cell catalysts Quarterly report, 15 Feb. - 15 May 1967
Catalytic activity of iron compounds for fuel cell catalyst
Inelastic contribution of the resistivity in the hidden order in URu2Si2
In the hidden order of URu2Si2 the resistivity at very low temperature shows
no T^2 behavior above the transition to superconductivity. However, when
entering the antiferromagnetic phase, the Fermi liquid behavior is recovered.
We discuss the change of the inelastic term when entering the AF phase with
pressure considering the temperature dependence of the Grueneisen parameter at
ambient pressure and the influence of superconductivity by an extrapolation of
high field data.Comment: 5 pages, 2 figures, SCES conference proceedin
Confirmation of a one-dimensional spin-1/2 Heisenberg system with ferromagnetic first-nearest-neighbor and antiferromagnetic second-nearest-neighbor interactions in RbCuMoO
We have investigated magnetic properties of RbCuMoO
powder. Temperature dependence of magnetic susceptibility and magnetic-field
dependence of magnetization have shown that this cuprate is a model compound of
a one-dimensional spin-1/2 Heisenberg system with ferromagnetic
first-nearest-neighbor (1NN) and antiferromagnetic second-nearest-neighbor
(2NN) competing interactions (competing system). Values of the 1NN and 2NN
interactions are estimated as K and K (). This value of suggests that the ground state is a
spin-singlet incommensurate state. In spite of relatively large and
, no magnetic phase transition appears down to 2 K, while an
antiferromagnetic transition occurs in other model compounds of the competing
system with ferromagnetic 1NN interaction. For that reason,
RbCuMoO is an ideal model compound to study properties of
the incommensurate ground state that are unconfirmed experimentally.Comment: 6 pages, 4 figure
Information-Seeking Activity of Rural Health Practitioners
Qualitative methods were used to identify the information-seeking activity (ISA) of rural health practitioners (non-physicians). Conditions shaping ISA were time, resources, and barriers. The primary strategy used was connecting with resources, particularly people. ISA led to consequences of problem resolution, greater competence, or more questions
Effects of hole-doping on the magnetic ground state and excitations in the edge-sharing CuO chains of CaYCuO
Neutron scattering experiments were performed on the undoped and hole-doped
CaYCuO, which consists of ferromagnetic edge-sharing
CuO chains. It was previously reported that in the undoped
CaYCuO there is an anomalous broadening of spin-wave
excitations along the chain, which is caused mainly by the antiferromagnetic
interchain interactions [Matsuda , Phys. Rev. B 63, 180403(R)
(2001)]. A systematic study of temperature and hole concentration dependencies
of the magnetic excitations shows that the magnetic excitations are softened
and broadened with increasing temperature or doping holes irrespective of
direction. The broadening is larger at higher . A characteristic feature is
that hole-doping is much more effective to broaden the excitations along the
chain. It is also suggested that the intrachain interaction does not change so
much with increasing temperature or doping although the anisotropic interaction
and the interchain interaction are reduced. In the spin-glass phase (=1.5)
and nearly disordered phase (=1.67) the magnetic excitations are much
broadened in energy and . It is suggested that the spin-glass phase
originates from the antiferromagnetic clusters, which are caused by the hole
disproportionation.Comment: 8 pages, submitted to Phys. Rev.
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