1,387 research outputs found
High Pressure Effects on Superconductivity in the beta-pyrochlore Oxides AOs2O6 (A=K, Rb, Cs)
Recently new pyrochlore oxides superconductors AOs2O6 (A=K,Rb,Cs) were found
and we measured the pressure dependence of magnetization up to 1.2 GPa in order
to deduce the pressure effect of Tc in the three beta-pyrochlore oxides. It is
found that the initial pressure dependence of Tc is positive for all the
compounds. Only KOs2O6 exhibits a saturation in Tc at 0.56 GPa and the downturn
at higher pressureComment: 7 pages, 2 figure
New beta-Pyrochlore Oxide Superconductor CsOs2O6
The discovery of a new beta-pyrochlore oxide superconductor CsOs2O6 with Tc =
3.3 K is reported. It is the third superconductor in the family of
beta-pyrochlore oxides, following KOs2O6 with Tc = 9.6 K and RbOs2O6 with Tc =
6.3 K. The Tc of this series decreases with increasing the ionic radius of
alkaline metal ions, imposing negative chemical pressure upon the Os pyrochlore
lattice.Comment: submitted to J. Phys. Soc Jp
Antiferromagnetic Exchange Interaction between Electrons on Degenerate LUMOs in Benzene Dianion
We discuss the ground state of Benzene dianion (Bz) on the basis of
the numerical diagonalization method of an effective model of orbitals.
It is found that the ground state can be the spin singlet state, and the
exchange coupling between LUMOs can be antiferromagnetic.Comment: Accepted for publication in J. Phys. Soc. Jpn., 2 pages, 3 figure
Anharmonicity in one-dimensional electron-phonon system
We investigate the effect of anharmonicity on the one-dimensional half-filled
Holstein model by using the determinant quantum Monte Carlo method. By
calculating the order parameters we find that with and without anharmonicity
there is always an transition from a disorder phase to a dimerized phase.
Moreover, in the dimerized phase a lattice dimerization and a charge density
wave coexist. The anharmonicity represented by the quartic term suppresses the
dimerization as well as the charge density wave, while a double-well potential
favors the dimerization. In addition, by calculating the correlation exponents
we show that the disorder phase is metallic with gapless charge excitations and
gapful spin excitations while in the dimerized phase both excitations are
gapful.Comment: 5 page
Exceptional type-I superconductivity of the layered silver oxide AgPbO
We report zero-resistivity transition and the details of magnetic transition
of a layered silver oxide AgPbO single crystal, which make
definitive evidence of superconductivity in this compound. In the AC
susceptibility of a mono-crystal, we observed large supercooling, as well as
positive peaks in the real part of the susceptibility indicating the
reversibility of magnetic process. These observations reveal that
AgPbO is probably the first oxide that shows type-I
superconductivity. Evaluation of the superconducting parameters not only gives
confirming evidence of type-I superconductivity, but also indicates that it is
a dirty-limit superconductor. We also analyze supercooling to determine the
upper limit of the Ginzburg-Landau parameter.Comment: v2: PACS numbers are adde
Anomalous magnetic phase in an undistorted pyrochlore oxide Cd2Os2O7 induced by geometrical frustration
We report on the muon spin rotation/relaxation study of a pyrochlore oxide,
Cd2Os2O7, which exhibits a metal-insulator (MI) transition at T_{MI}~225 K
without structural phase transition. It reveals strong spin fluctuation
(>10^8/s) below the MI transition, suggesting a predominant role of geometrical
spin frustration amongst Os^{5+} ions. Meanwhile, upon further cooling, a
static spin density wave discontinuously develops below T_{SDW}~150 K. These
observations strongly suggest the occurrence of an anomalous magnetic
transition and associated change in the local spin dynamics in undistorted
pyrochlore antiferromagnet.Comment: 5 pages, 4 figure
Multiple superconducting transitions in the Sr3Ru2O7 region of Sr3Ru2O7-Sr2RuO4 eutectic crystals
We report superconducting properties of Sr3Ru2O7-Sr2RuO4 eutectic crystals,
consisting of the spin-triplet superconductor Sr2RuO4 with a monolayer stacking
of RuO2 planes and the metamagnetic normal metal Sr3Ru2O7 with a bilayer
stacking. Although Sr3Ru2O7 has not been reported to exhibit superconductivity
so far, our AC susceptibility measurements revealed multiple superconducting
transitions occurring in the Sr3Ru2O7 region of the eutectic crystals. The
diamagnetic shielding essentially reached the full fraction at low AC fields
parallel to the c axis. However, both the shielding fraction and the onset
temperature are easily suppressed by AC fields of larger than 0.1 mT-rms and no
anomaly was observed in the specific heat. Moreover, the critical field curves
of these transitions have a positive curvature near zero fields, which is
different from the upper critical field curve of the bulk Sr2RuO4. These facts
suggest that the superconductivity observed in the Sr3Ru2O7 region is not a
bulk property. To explain these experimental results, we propose the scenario
that stacking RuO2 planes, the building block of superconducting Sr2RuO4, are
contained in the Sr3Ru2O7 region as stacking faults.Comment: 8 pages, 10 figures, accepted for publication in Phys. Rev.
Emission pricing and CO2 compensation in the EU. The optimal compensation to the power-intensive and trade-exposed industries for increased electricity prices
Unilateral CO2 emission reduction can lead to carbon leakage, such as relocation of power-intensive
and trade-exposed industries. In the EU emission trading system, these industries are also subjected
to higher cost of electricity due to emission pricing in this sector. As a result, the industries in the EU
receive free emission allowances to mitigate carbon leakage as well as CO2 compensation due to
higher electricity cost. This paper examines the welfare effects of supplementing free allowances
with a CO2 compensation on the power-intensive and trade-exposed goods. The analytical results
suggest that introducing CO2 compensation has a regional and global welfare improving effect
under certain plausible conditions. Numerical simulations in the context of the EU ETS support the
analytical findings if the emission reduction target is stringent enough
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