24,847 research outputs found
Fermi-liquid ground state in n-type copper-oxide superconductor Pr0.91Ce0.09LaCuO4-y
We report nuclear magnetic resonance studies on the low-doped n-type
copper-oxide Pr_{0.91}LaCe_{0.09}CuO_{4-y} (T_c=24 K) in the superconducting
state and in the normal state uncovered by the application of a strong magnetic
field. We find that when the superconductivity is removed, the underlying
ground state is the Fermi liquid state. This result is at variance with that
inferred from previous thermal conductivity measurement and contrast with that
in p-type copper-oxides with a similar doping level where high-T_c
superconductivity sets in within the pseudogap phase. The data in the
superconducting state are consistent with the line-nodes gap model.Comment: version to appear in Phys. Rev. Let
Hydration-induced anisotropic spin fluctuations in Na_{x}CoO_{2}\cdot1.3H_{2}O superconductor
We report ^{59}Co NMR studies in single crystals of cobalt oxide
superconductor Na_{0.42}CoO_{2}\cdot1.3H_{2}O (T_c=4.25K) and its parent
compound Na_{0.42}CoO_{2}. We find that both the magnitude and the temperature
(T) dependence of the Knight shifts are identical in the two compounds above
T_c. The spin-lattice relaxation rate (1/T_1) is also identical above T_0
\sim60 K for both compounds. Below T_0, the unhydrated sample is found to be a
non-correlated metal that well conforms to Fermi liquid theory, while spin
fluctuations develop in the superconductor. These results indicate that water
intercalation does not change the density of states but its primary role is to
bring about spin fluctuations. Our result shows that, in the hydrated
superconducting compound, the in-plane spin fluctuation around finite wave
vector is much stronger than that along the c-axis, which indicates that the
spin correlation is quasi-two-dimensional.Comment: 4 pages, 5 figure
Thermodynamic analysis of methane-fueled solid oxide fuel cells considering co electrochemical oxidation
2014-2015 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
A Dispersive Analysis on the and Resonances in Processes
We estimate the di-photon coupling of , and
resonances in a coupled channel dispersive approach. The di-photon
coupling is also reinvestigated using a single channel matrix for
scattering with better analyticity property, and it is found to be
significantly smaller than that of a state. Especially we also
estimate the di-photon coupling of the third sheet pole located near
threshold, denoted as .
It is argued that this third sheet pole may be originated from a coupled
channel Breit-Wigner description of the resonance.Comment: 24 pages and 13 eps figures. A nuerical bug in previous version is
fixed. Some results changed. References and new figures added. Version to
appear in Phys. Rev.
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