Three-dimensional electronic structures and the metal-insulator transition in Ruddlesden-Popper iridates

Yamasaki, Atsushi*; Fujiwara, Hidenori*; Tachibana, Shoichi*; Iwasaki, Daisuke*; Higashino, Yuji*; Yoshimi, Chiaki*; Nakagawa, Koya*; Nakatani, Yasuhiro*; Yamagami, Kohei*; Aratani, Hidekazu*; et al.

Physical Review B, 94(11), p.115103_1 - 115103_10, 2016/11

AA2016-0587.pdf:2.55MB

https://doi.org/10.1103/PhysRevB.94.115103

In this study, we systematically investigate three-dimensional(3D) momentum-resolved electronic structures of Ruddlesden-Popper-type iridium oxides SrIrO using soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO-plane structure. This transition occurs when the spin-orbit-coupled = 1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. By scanning the photon energy over 350 eV, we reveal the 3D Fermi surface in SrIrO and -dependent oscillations of photoelectron intensity in SrIrO. To corroborate the physics deduced using low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful complementary technique, as this method surveys more than one whole Brillouin zone and provides a panoramic view of electronic structures.

Model magnet development of D1 beam separation dipole for the HL-LHC upgrade

Nakamoto, Tatsushi*; Sugano, Michinaka*; Xu, Q.*; Kawamata, Hiroshi*; Enomoto, Shun*; Higashi, Norio*; Idesaki, Akira; Iio, Masami*; Ikemoto, Yukio*; Iwasaki, Ruri*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4000505_1 - 4000505_5, 2015/06

https://doi.org/10.1109/TASC.2014.2361404

Recently, development of superconducting magnet system with high radiation resistance has been demanded for application in accelerator facilities such as CERN LHC. In order to realize superconducting magnet system with high radiation resistance, it is necessary to develop electrical insulator with high radiation resistance because the electrical insulator is made of organic materials whose radiation resistance is inferior to that of inorganic materials. We developed a glass fiber reinforced plastic with bismaleimide-triazine resin. The developed material showed excellent radiation resistance; the material evolved gases of 510 mol/g and maintained flexural strength of 640MPa (90% of initial value).

Evaluation of sodium combustion in the JSFR SCCV

Kato, Atsushi; Chikazawa, Yoshitaka; Yamamoto, Tomohiko; Ohno, Shuji; Kubo, Shigenobu; Sakaba, Hiroshi*; Akiyama, Yo*; Iwasaki, Mikinori*

Proceedings of 2013 International Congress on Advances in Nuclear Power Plants (ICAPP 2013) (USB Flash Drive), 9 Pages, 2013/04

After the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Plant, evaluations of severe events beyond the design basis on a NPP are focused. As one of those activities, wide range of sodium combustion and hydrogen generation potentials have been analyzed to investigate potential consequences on SCCV. Structural and boundary integrity of SCCV have been evaluated from sodium combustion analyses for pressure and temperature loads. Hydrogen generation has also been evaluated as potential loads of SCCV.

Location of deuterium atoms in BaZrInO by neutron powder diffraction

Nagasaki, Takanori*; Ito, Tsuyoshi*; Yoshino, Masahito*; Iwasaki, Kota*; Shiotani, Shinya*; Fukazawa, Hiroshi; Igawa, Naoki; Ishii, Yoshinobu*

Journal of Nuclear Science and Technology, 45(Suppl.6), p.122 - 127, 2008/09

https://doi.org/10.1080/00223131.2008.10875992

The neutron powder diffraction measurement was carried out at 10 K on the proton-conducting oxide BaZrInO with and without dissolved DO. Obtained diffraction data were analyzed by the Rietveld method and the maximum entropy method. It was found that deuterium atoms were located close the 12 site of the cubic perovskite structure with the space group -.

Energy spectra of electrons induced by MeV atom clusters

Kudo, Hiroshi*; Iwasaki, Wataru*; Uchiyama, Rumi*; Tomita, Shigeo*; Shima, Kunihiro*; Sasa, Kimikazu*; Ishii, Satoshi*; Narumi, Kazumasa; Naramoto, Hiroshi; Saito, Yuichi; et al.

Japanese Journal of Applied Physics, Part 2, 45(22), p.L565 - L568, 2006/06

https://doi.org/10.1143/JJAP.45.L565

The first observation of the energy distribution of electrons emitted from solids bombarded by MeV atom clusters is reported. In the backward direction, using graphite and Si bombarded by C and Al (n 8), an appreciable suppression of electron emission has been observed at electron energies lower than 10 eV. Electron yield per atom decreases with increasing n, and becomes less than 50% at n 3, relative to the case of n = 1. The experimental results cannot be explained in terms of projectile stopping cross sections nor by the clearing-the-way effect. It is probable that the suppressed electron emission is a result of the suppression of the transport or surface transmission of the produced low-energy electrons, rather than of the suppression of ionization.

Reconstruction of CT images by the Bayes-back projection method

Haruyama, Mitsuo; Takase, Misao*; Iwasaki, Shin*; Tobita, Hiroshi

JAERI-Research 2002-022, 91 Pages, 2002/12

JAERI-Research-2002-022.pdf:37.97MB

In the course of research on quantitative assay of non-destructive measurement of radioactive waste, the authors have developed a unique program based on the Bayesian theory for reconstruction of transmission computed tomography (TCT) image. The reconstruction of cross-section images in the CT technology usually employs the Filtered Back Projection method. The new imaging reconstruction program reported here is based on the Bayesian Back Projection method, and it has a function of iterative improvement images by every step of measurement. Namely, this method has the capability of prompt display of a cross-section image corresponding to each angled projection data from every measurement. Hence, it is possible to observe an improved cross-section view by reflecting each projection data in almost real time. The present reconstruction program developed here for the -ray CT can widely applied also to, for instance, the Neutron Imaging and the Positron Emission Tomography (PET).

High-resolution resonance photoemission study of Ce (=Pt, Pd; =P, As, Sb)

Iwasaki, T.*; Sekiyama, Akira*; Yamasaki, Atsushi*; Okazaki, Makoto*; Kadono, Koji*; Utsunomiya, Hiroshi*; Imada, Shin*; Saito, Yuji; Muro, Takayuki*; Matsushita, Tomohiro*; et al.

Physical Review B, 65(19), p.195109_1 - 195109_9, 2002/05

https://doi.org/10.1103/PhysRevB.65.195109

no abstracts in English

Characterization of the granitic rock by meas of the borehole radar; On the result of the measurements at the Kamaishi mine in-situ experiment site

Semba, Takeshi; Ogata, Nobuhisa; Hasegawa, Ken; Iwasaki, Hiroshi*; Watanabe, Kunio*

PNC TN7410 92-005, 22 Pages, 1992/03

PNC-TN7410-92-005.pdf:0.86MB

Power Reactor and Nuclear Fuel Development Corporation (PNC) has been developping techniques for evaluation of groundwater flow in the granitic rock as crystalline rock. In a link of this purpose, PNC introduced the borehole radar system (RAMAC) which was developped in Stripa Project by OECD/Nuclear Energy Agency because it is essential to investigate the spatial extent and dimensions of fracture zones. This report describes the results of crosshole measurements which were performed with RAMAC system at the Kamaishi In-situ Experiment Site in the northern part of Honsyu Island, Japan. Crosshole measurements were performed with four boreholes which were drilled at G.L. -260 meters. The tomographic inversion was made using crosshole data and figures of slowness distribution were interpreted. Integrated analysis on the tomogurams was carried out in the combination of the observation of the fracture zones with flowing groundwater. The results are summarized as follows; (1)Spatial extent of some low velocity zones and high velocity zones of electromagnetic waves were delineated. (2)Most of the seeping points identified by borehole TV lies in the low velocity zones. (3)The low velocity zones exactly correspond to the fracture-concentrated zones or fracture zones with flowing groundwater recognized on the walls of the gallery, which was excavated after drilling of the boreholes. (4)This may indicate that low velocity zones obtained by the borehole radar measurements corresponds with fracture-concentrated zones or fracture zones with groundwater in the deep underground.

Deuteron site in BaSnInO and its change with temperature by neutron powder diffraction

Ito, Tsuyoshi*; Nagasaki, Takanori*; Iwasaki, Kota*; Yoshino, Masahito*; Matsui, Tsuneo*; Fukazawa, Hiroshi; Igawa, Naoki; Ishii, Yoshinobu

no journal, , 

no abstracts in English

Location of deuterium atoms in BaSnInO-DO at 77-473 K by neutron powder diffraction, 2

Ito, Tsuyoshi*; Nagasaki, Takanori*; Iwasaki, Kota*; Yoshino, Masahito*; Matsui, Tsuneo*; Fukazawa, Hiroshi; Igawa, Naoki; Ishii, Yoshinobu

no journal, , 

no abstracts in English