Magnetic-field effects on the in-plane electrical resistivity in the single-crystal La2−x_{2-x}Bax_xCuO4_4 and La1.6−x_{1.6-x}Nd0.4_{0.4}Srx_xCuO4_4 around x=1/8x=1/8: Relating to the field-induced stripe order

Temperature dependence of the in-plane electrical resistivity, $\rho_{\rm ab}$, in various magnetic fields has been measured in the single-crystal La$_{2-x}$Ba$_x$CuO$_4$ with $x=0.08$, 0.10, 0.11 and La$_{1.6-x}$Nd$_{0.4}$Sr$_x$CuO$_4$ with $x=0.12$. It has been found that the superconducting transition curve shows a so-called fan-shape broadening in magnetic fields for $x=0.08$, while it shifts toward the low-temperature side in parallel with increasing field for $x=0.11$ and 0.12 where the charge-spin stripe order is formed at low temperatures. As for $x=0.10$, the broadening is observed in low fields and it changes to the parallel shift in high fields above 9 T. Moreover, the normal-state value of $\rho_{\rm ab}$ at low temperatures markedly increases with increasing field up to 15 T. It is possible that these pronounced features of $x=0.10$ are understood in terms of the magnetic-field-induced stabilization of the stripe order suggested from the neutron-scattering measurements in the La-214 system. The $\rho_{\rm ab}$ in the normal state at low temperatures has been found to be proportional to ln(1/$T$) for $x=0.10$, 0.11 and 0.12. The ln(1/$T$) dependence of $\rho_{\rm ab}$ is robust even in the stripe-ordered state.Comment: 6 pages, 4 figures, ver. 2 has been accepted for publication in Phys. Rev.

Effect of layer charge on chemical and physical properties of synthetic K-fluorine micas

The original publication is available at www.springerlink.com.ArticleJOURNAL OF MATERIALS SCIENCE. 40(21): 5597-5602 (2005)journal articl

Formation of hydrogen-boron complexes in boron-doped silicon treated with a high concentration of hydrogen atoms

The formation of hydrogen (H) related complexes and their effect on boron (B) dopant were investigated in B-ion implanted and annealed silicon (Si) substrates treated with a high concentration of H. Isotope shifts by replacement of 10B with 11B were observed for some H-related Raman peaks, but not for other peaks. This shows proof of the formation of B-H complexes in which H directly bonds to B in Si. This is an experimental result concerning the formation of B-H complexes with H bonded primarily to B. Electrical resistivity measurements showed that the B acceptors are passivated via the formation of the observed B-H complexes, as well as the well-known passivation center in B-doped Si; namely, the H-B passivation center

Extraction of a strongly focusing He + beam from three-stage concave electrodes for alpha particle measurement system in ITER

A strongly focusing He + ion beam source equipped with concave multi-aperture electrodes was developed for production of He - through a charge exchange cell. The beam was extracted at a voltage less than 20 kV from 301 apertures distributed in an area of 100 mm , and focused at 750 mm distance. The beam current and the beam size of 2 A and 20 mm in diameter, respectively, were achieved with an arc power less than 10 kW. The optimum perveance was obtained at 0.02 AkV 1.5 at the beam energy less than 20 keV which is suitable for the conversion to He - in an alkali vapor cell

Observation of multi-scale turbulence and non-local transport in LHD plasmas

We have studied two types of spatio-temporal turbulence dynamics in plasmas in the Large Helical Device, based on turbulence measurements with high spatial and temporal resolution. Applying conditional ensemble-averaging to a plasma with Edge-Localized Modes (ELMs), fast radial inward propagation of a micro-scale turbulence front is observed just after ELM event, and the propagation speed is evaluated as ??100m/s. A self-organized radial electric field structure is observed in an electrode biasing experiment, and it is found to realize a multi-valued state. The curvature of the radial electric field is found to play an important role for turbulence reduction

Characterization of scintillators for lost alpha diagnostics on burning plasma experiments

The characteristics of light output by ion beam irradiations under high ion fluxes have been measured for three kinds of scintillators: ZnS:Ag deposited on the glass plate, Y_3Al_5O_12:Ce powder stiffened with a binder, and Y_3Al_5O_12:Ce ceramics sintered at high temperature. The ion beam flux in the range from 10^12 to 10^13 ions/(cm^2 s) is irradiated to simulate the burning plasma experiments. The decrease of light output has been observed by long time ion irradiation. The deterioration of ZnS:Ag deposited scintillator is most serious. The deterioration has been improved for the scintillators of Y_3Al_5O_12:Ce with a binder and that sintered. Their applications to ITER lost alpha diagnostics are discussed