1,514 research outputs found
In-situ growth of superconducting NdFeAs(O,F) thin films by Molecular Beam Epitaxy
The recently discovered high temperature superconductor F-doped LaFeAsO and
related compounds represent a new class of superconductors with the highest
transition temperature (Tc) apart from the cuprates. The studies ongoing
worldwide are revealing that these Fe-based superconductors are forming a
unique class of materials that are interesting from the viewpoint of
applications. To exploit the high potential of the Fe-based superconductors for
device applications, it is indispensable to establish a process that enables
the growth of high quality thin films. Efforts of thin film preparation started
soon after the discovery of Fe-based superconductors, but none of the earlier
attempts had succeeded in an in-situ growth of a superconducting film of
LnFeAs(O,F) (Ln=lanthanide), which exhibits the highest Tc to date among the
Fe-based superconductors. Here, we report on the successful growth of
NdFeAs(O,F) thin films on GaAs substrates, which showed well-defined
superconducting transitions up to 48 K without the need of an ex-situ heat
treatment
Detection of the linear radical HC4N in IRC+10216
We report the detection of the linear radical HC4N in the C-rich envelope of
IRC+10216. After HCCN, HC4N is the second member of the allenic chain family
HC_(2n)N observed in space. The column density of HC4N is found to be 1.5
10**12 cm**(-2). The abundance ratio HC2N/HC4N is 9, a factor of two larger
than the decrement observed for the cyanopolyynes HC$_(2n+1)N/HC_(2n+3)N.
Linear HC_4N has a 3-Sigma electronic ground state and is one of the 3
low-energy isomeric forms of this molecule. We have searched for the bent and
ringed HC4N isomers, but could only derive an upper limit to their column
densities of about 3 10**(12) cm**(-2).Comment: Preprint of 10 page
Momentum dependence of the energy gap in the superconducting state of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu)
The energy gap of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu) was probed by
angle resolved photoemission spectroscopy (ARPES) using a vacuum ultraviolet
laser (photon energy 6.994 eV) or He I resonance line (21.218 eV) as photon
source. The results show that the gap around the node at sufficiently low
temperatures can be well described by a monotonic d-wave gap function for both
samples and the gap of the R=La sample is larger reflecting the higher Tc.
However, an abrupt deviation from the d-wave gap function and an opposite R
dependence for the gap size were observed around the antinode, which represent
a clear disentanglement between the antinodal pseudogap and the nodal
superconducting gap.Comment: Submitted as the proceedings of LT2
Growth-related profiles of remanent flux in bulk melt-textured YBaCuO crystal magnetized by pulsed fields
We have studied the remanent magnetic flux distribution in bulk melt-textured
YBa2Cu3O7 (YBCO) crystals after their magnetization in quasi-static and pulsed
magnetic fields up to 6T. It has been shown that, provided that the magnetic
pulse is sharp enough and its amplitude much exceeds the twice penetration
magnetic field, the pulse magnetization technique becomes extremely sensitive
to the sample inhomogeneities. Using this method with appropriate parameters of
the magnetic pulse, we have particularly demonstrated that the growth of YBCO
crystals in the growth sectors (GSs) responds for a macroscopic arrangement of
weaks links -- they mostly appear inside of GSs, but not along the GS
boundaries.Comment: 8 pages in LaTeX2e, 5 figures. Revised version, submitted to
Supercond. Sci. Techno
Single grain (LRE)-Ba-Cu-O superconductors fabricated by top seeded melt growth in air
We have recently reported a practical processing method for the fabrication in air of large, single grain (LRE)-Ba-Cu-O [where LRE Nd, Sm, Eu and Gd] bulk superconductors that exhibit high Tc and high Jc. The process is based initially on the development of a new type of generic seed crystal that can promote effectively the epitaxial nucleation of any (RE)-Ba-Cu-O system and, secondly, by suppressing the formation of (LRE)/Ba solid solution in a controlled manner within large LRE-Ba-Cu-O grains processed in air. In this paper we investigate the degree of homogeneity of large grain Sm-Ba-Cu-O superconductors fabricated by this novel process. The technique offers a significant degree of freedom in terms of processing parameters and reproducibility in the growth of oriented single grains in air and yields bulk samples with significantly improved superconducting and field-trapping properties compared to those processed by conventional top seeded melt growth (TSMG)
A Case History of Raft Foundation Behavior for a Large-Scaled Building Complex
This paper describes the field observation of settlement of a raft foundation for a large scale building complex in Nagoya city in Japan. The complex consists of a 28 story hotel, a 15 story office building and a low-storied banquet hall in the middle all of which are supported on a single 80 m square basement on raft foundation. Since the load on the foundation is non-uniform, the differential settlement of the foundation was investigated analytically, taking into consideration the interaction between the ground and the raft. To confirm the validity of the design, measurements were conducted for about 2 years during the building construction. The results of the measurement are discussed below
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