3,186 research outputs found
Three-orbital study on the orbital distillation effect in the high Tc cuprates
Our recent study has revealed that the mixture of the dz2 orbital component
into the Fermi surface suppresses Tc in the cuprates such as La2CuO4. We have
also shown that applying hydrostatic pressure enhances Tc due to smaller mixing
of the Cu4s component. We call these the "orbital distillation" effect. In our
previous study, the 4s orbital was taken into account through the hoppings in
the dx2-y2 sector, but here we consider a model in which of the dx2-y2, dz2 and
4s orbitals are all considered explicitly. The present study reinforces our
conclusion that smaller 4s hybridization further enhances Tc.Comment: 4 pages, 2 figures, submitted as a proceeding of ISS2012(Tokyo
Aerodynamic investigation of an air-cooled axial-flow turbine. Part 2: Rotor blade tip-clearance effects on overall turbine performance and internal gas flow conditions: Experimental results and prediction methods
Total turbine blade performance was investigated while changing the blade tip clearance in three ways. The internal flow at the moving blade outlet point was measured. Experimental results were compared with various theoretical methods. Increased blade clearance leads to decreased turbine efficiency
Incommensurate spin fluctuations in hole-overdoped superconductor KFe2As2
A neutron scattering study of heavily hole-overdoped superconducting
KFeAs revealed a well-defined low-energy incommensurate spin
fluctuation at [),0] with = 0.16. The incommensurate
structure differs from the previously observed commensurate peaks in
electron-doped FeAs ( = Ba, Ca, or Sr) at low energies. The
direction of the peak splitting is perpendicular to that observed in Fe(Te,Se)
or in Ba(Fe,Co)As at high energies. A band structure calculation
suggests interband scattering between bands around the and X points as
an origin of this incommensurate peak. The perpendicular direction of the peak
splitting can be understood within the framework of multiorbital band
structure. The results suggest that spin fluctuation is more robust in
hole-doped than in electron-doped samples, which can be responsible for the
appearance of superconductivity in the heavily hole-doped samples.Comment: 4 pages, 4 figure
Proceedings of the Meeting and the workshop "Algebraic Geometry and Hodge Theory" Vol.I
Meeting:August23-28, 1989, Hokkaido University Workshop:November 28-December 1,1989,Kochi Universit
Photometric Observations of Star Formation Activity in Early Type Spirals
We observationally study the current star formation activities of early type
spiral galaxies. We construct a complete sample of 15 early type spirals having
far-infrared (FIR) to optical B band luminosity ratios, L(FIR)/L(B), larger
than the average of the type, and make their CCD imaging of the R and H-alpha
bands. The equivalent widths of H-alpha emission increase with increasing
L(FIR)/L(B), indicating that L(FIR)/L(B) can be an indicator of star formation
for such early type spirals with star formation activities higher than the
average. For all of the observed early type spirals, the extended HII regions
exist at the central regions with some asymmetric features. H-alpha emission is
more concentrated to the galactic center than the R band light, and the degree
of the concentration increases with the star formation activity. We also
analyze the relation between the star formation activities and the existence of
companion galaxies in the sample galaxies and other bright early type spirals.
No correlation is found and this suggests that the interaction is not
responsible for all of the star formation activities of early type spirals.Comment: LaTex, 23 pages (2 tables included), plus 9 Postscript figures & 1
table. To be published in AJ (November issue
Low-Degree Partial Melting Experiments of CR and H Chondrite Compositions: Implications for Asteroidal Magmatism Recorded in GRA 06128 and GRA 06129 T
Studies of differentiated meteorites have revealed a diversity of differentiation processes on their parental asteroids; these differentiation mechanisms range from whole-scale melting to partial melting without the core formation [e.g., 1]. Recently discovered paired achondrites GRA 06128 and GRA 06129 (hereafter referred to as GRA) represent unique asteroidal magmatic processes. These meteorites are characterized by high abundances of sodic plagioclase and alkali-rich whole-rock compositions, implying that they could originate from a low-degree partial melt from a volatile-rich oxidized asteroid [e.g., 2, 3, 4]. These conditions are consistent with the high abundances of highly siderophile elements, suggesting that their parent asteroid did not segregate a metallic core [2]. In this study, we test the hypothesis that low-degree partial melts of chondritic precursors under oxidizing conditions can explain the whole-rock and mineral chemistry of GRA based on melting experiments of synthesized CR- and H-chondrite compositions
Proceedings of the Meeting and the workshop "Algebraic Geometru and Hodge Theory" Vol.II
Meeting:Augusy 23-28, Hokkaido Univetsity Workshop:November 28-December 1, 1989, Kochi Universit
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