213 research outputs found
Incombustible resin composition
Incombustible resin compositions composed of aromatic compounds were obtained through (1) combustion polymer material and (2) bisphenol A or halogenated bisphenol A and bisphenol A diglycidl ether or halogenated bisphenol A diglycidyl ether. The aromatic compound is an adduct of bifunctional phenols and bifunctional epoxy resins
Hybrid Micro-Gravity Simulator Consisting of a High-speed Parallel Robot
科研費報告書収録論文(課題番号:08555062・基盤研究(A)(2)・H8~H10/研究代表者:内山, 勝/6自由度超高速パラレルロボットの試作研究
Quasi-particle Density in Sr2RuO4 Probed by means of the Phonon Thermal Conductivity
The thermal conductivity of Sr2RuO4 along the least conducting direction
perpendicular to the RuO2 plane has been studied down to 0.3 K. In this
configuration the phonons remain the dominant heat carriers down to the lowest
temperature, and their conductivity in the normal state is determined by the
scattering on conduction electrons. We show that the phonon mean free path in
the superconducting state is sensitive to the density of the quasi-particles in
the bulk. An unusual magnetic field dependence of the phonon thermal
conductivity is ascribed to the anisotropic superconducting gap structure in
Sr2RuO4.Comment: 14 pages, 6 eps figures, Latex. This article corresponds to the
reference 25 of Phys. Rev. Lett. vol.86 page2649-2652 (2001) and
cond-mat/010449
Interface superconductivity in the eutectic Sr2RuO4-Ru: 3-K phase of Sr2RuO4
The eutectic system Sr2RuO4-Ru is referred to as the 3-K phase of the
spin-triplet supeconductor Sr2RuO4 because of its enhanced superconducting
transition temperature Tc of ~3 K. We have investigated the field-temperature
(H-T) phase diagram of the 3-K phase for fields parallel and perpendicular to
the ab-plane of Sr2RuO4, using out-of-plane resistivity measurements. We have
found an upturn curvature in the Hc2(T) curve for H // c, and a rather gradual
temperature dependence of Hc2 close to Tc for both H // ab and H // c. We have
also investigated the dependence of Hc2 on the angle between the field and the
ab-plane at several temperatures. Fitting the Ginzburg-Landau effective-mass
model apparently fails to reproduce the angle dependence, particularly near H
// c and at low temperatures. We propose that all of these charecteric features
can be explained, at least in a qualitative fashion, on the basis of a theory
by Sigrist and Monien that assumes surface superconductivity with a
two-component order parameter occurring at the interface between Sr2RuO4 and Ru
inclusions. This provides evidence of the chiral state postulated for the 1.5-K
phase by several experiments.Comment: 7 pages and 5 figs; accepted for publication in Phys. Rev.
Superconducting Properties under Magnetic Field in NaCoOHO Single Crystal
We report the in-plane resistivity and magnetic susceptibility of the layered
cobalt oxide NaCoOHO single crystal. The
temperature dependence of the resistivity shows metallic behavior from room
temperature to the superconducting transition temperature of 4.5 K.
Sharp resistive transition, zero resistivity and almost perfect superconducting
volume fraction below indicate the good quality and the bulk
superconductivity of the single crystal. The upper critical field and
the coherence length are obtained from the resistive transitions in
magnetic field parallel to the c-axis and the -plane. The anisotropy of
, 12 nm/1.3 nm 9.2, suggests that this
material is considered to be an anisotropic three dimensional superconductor.
In the field parallel to the -plane, seems to be suppressed to the
value of Pauli paramagnetic limit. It may indicate the spin singlet
superconductivity in the cobalt oxide.Comment: 4 pages, 4 figure
Detailed study of the ac susceptibility of Sr2RuO4 in oriented magnetic fields
We have investigated the ac susceptibility of the spin triplet superconductor
SrRuO as a function of magnetic field in various directions at
temperatures down to 60 mK. We have focused on the in-plane field configuration
(polar angle ), which is a prerequisite for inducing
multiple superconducting phases in SrRuO. We have found that the
previous attribution of a pronounced feature in the ac susceptibility to the
second superconducting transition itself is not in accord with recent
measurements of the thermal conductivity or of the specific heat. We propose
that the pronounced feature is a consequence of additional involvement of
vortex pinning originating from the second superconducting transition.Comment: Accepted for publication in Phys. Rev.
Spin-triplet superconductivity due to antiferromagnetic spin-fluctuation in Sr_2RuO_4
A mechanism leading to the spin-triplet superconductivity is proposed based
on the antiferromagnetic spin fluctuation. The effects of anisotropy in spin
fluctuation on the Cooper pairing and on the direction of d vector are examined
in the one-band Hubbard model with RPA approximation. The gap equations for the
anisotropic case are derived and applied to Sr_2RuO_4. It is found that a
nesting property of the Fermi surface together with the anisotropy leads to the
triplet superconductivity with the d=z(sin{k_x}\pm isin{k_y}), which is
consistent with experiments.Comment: 4 pages, 3 eps figures, revte
Upper critical field in layered superconductors
The theoretical statements about a restoration of a superconductivity at
magnetic fields higher than the quasiclassical upper critical field and a
reentrance of superconductivity at temperatures in the
superconductors with open Fermi surfaces are reinvestigated taking into account
a scattering of quasiparticles on the impurities.
The system of integral equations for determination of the upper critical
field parallel to the conducting planes in a layered conventional and
unconventional superconductors with impurities are derived. The
values for the "clean" case in the Ginzburg-Landau regime and at any
temperature in the "dirty" case are found analytically. The upper limit of the
superconductor purity when the upper critical field definately has a finite
value is established.Comment: 10 page
Low temperature electronic properties of Sr_2RuO_4 III: Magnetic fields
Based on the microscopic model introduced previously the observed specific
heat and ac-susceptibility data in the superconducting phase in Sr_2RuO_4 with
applied magnetic fields are described consistently within a phenomenological
approach. Discussed in detail are the temperature dependence of the upper
critical fields H_{c2} and H_2, the dependence of the upper critical fields on
the field direction, the linear specific heat below the superconducting phase
transition as a function of field or temperature, the anisotropy of the two
spatial components of the order parameter, and the fluctuation field H_p.Comment: 8 pages REVTEX, 4 figure
Field dependence of the vortex structure in chiral p-wave superconductors
To investigate the different vortex structure between two chiral pairing p_x
+(-) i p_y, we calculate the pair potential, the internal field, the local
density of states, and free energy in the vortex lattice state based on the
quasiclassical Eilenberger theory, and analyze the magnetic field dependence.
The induced opposite chiral component of the pair potential plays an important
role in the vortex structure. It also produces H^{1/2}-behavior of the
zero-energy density of states at higher field. These results are helpful when
we understand the vortex states in Sr2RuO4.Comment: 11 pages, 10 figures, to be published in Phys. Rev.
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