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131 results on '"Kobata, M."'

1. Empirical relationship between x-ray photoemission spectra and electrical conductivity in a colossal magnetoresistive manganite La_{1-x}Sr_{x}MnO_{3}

Author

Hishida, T., Ohbayashi, K., Kobata, M., Ikenaga, E., Sugiyama, T., Kobayashi, K., Okawa, M., and Saitoh, T.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract

By using laboratory x-ray photoemission spectroscopy (XPS) and hard x-ray photoemission spectroscopy (HX-PES) at a synchrotron facility, we report an empirical semi-quantitative relationship between the valence/core-level x-ray photoemission spectral weight and electrical conductivity in La_{1-x}Sr_{x}MnO_{3} as a function of x. In the Mn 2p_{3/2} HX-PES spectra, we observed the shoulder structure due to the Mn^{3+} well-screened state. However, the intensity at x=0.8 was too small to explain its higher electrical conductivity than x=0.0, which confirms our recent analysis on the Mn 2p_{3/2} XPS spectra. The near-Fermi level XPS spectral weight was found to be a measure of the variation of electrical conductivity with x in spite of a far lower energy resolution compared with the energy scale of the quasiparticle (coherent) peak because of the concurrent change of the coherent and incoherent spectral weight., Comment: 6 pages, 4 figures, 1 supplemental material

Published
2013
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2. Identifying the electronic character and role of the Mn states in the valence band of (Ga,Mn)As

Author

Fujii, J., Salles, B. R., Sperl, M., Ueda, S., Kobata, M., Kobayashi, K., Yamashita, Y., Torelli, P., Utz, M., Fadley, C. S., Gray, A. X., Minar, J., Braun, J., Ebert, H., Di Marco, I., Eriksson, O., Thunström, P., Fecher, G. H., Ouardi, S., Stryhanyuk, H., Ikenaga, E., Back, C. H., van der Laan, G., and Panaccione, G.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract

We report high-resolution hard x-ray photoemission spectroscopy results on (Ga,Mn)As films as a function of Mn doping. Supported by theoretical calculations we identify, over the entire 1% to 13% Mn doping range, the electronic character of the states near the top of the valence band. Magnetization and temperature dependent core-level photoemission spectra reveal how the delocalized character of the Mn states enables the bulk ferromagnetic properties of (Ga,Mn)As., Comment: prl submitted

Published
2013
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12. Structural characteristics of GeTe-rich GeTe–Sb2Te3 pseudobinary metastable crystals.

Author

Matsunaga, T., Morita, H., Kojima, R., Yamada, N., Kifune, K., Kubota, Y., Tabata, Y., Kim, J.-J., Kobata, M., Ikenaga, E., and Kobayashi, K.

Subjects
PHYSICAL & theoretical chemistry, HEATING equipment, STOICHIOMETRY, ABSORPTION, PHYSICS
Abstract

The (GeTe)1-γ–(Sb2Te3)γ pseudobinary system has, over almost its entire composition range, two kinds of crystalline phase: one is a metastable phase with a NaCl-type structure and the other is a spectrum of stable phases with homologous structures. In the metastable phase, Ge/Sb atoms and intrinsic vacancies occupy the Na sites; on the other hand, Te atoms are located at the Cl sites. These vacancies are produced by following γ/1+2γ to ensure the stoichiometry of the metastable pseudobinary compound. This metastable phase obstinately holds its NaCl-type structure and resists transformation to stable homologous structures, even at high temperatures on the GeTe-rich side of the system. In GeTe (γ=0), the NaCl-type atomic configuration itself is the stable structure. GeTe has, as is well known, a high-temperature cubic phase and a low-temperature rhombohedral phase. This GeTe and the pseudobinary compounds containing a small quantity of Sb2Te3 have their single-phase regions not on the GeTe–Sb2Te3 tie line but at Ge-poor sides off the line: in other words, the Na sites of these off-stoichiometric compounds have some excess vacancies besides the intrinsic vacancies. As Sb2Te3 is further added to GeTe, however, the structural transformation temperature continuously falls and the single-phase region converges on the tie line as the excess vacancies at the Na site disappear, which change its electrical property from metallic to semiconducting conductivity. The low-temperature rhombohedral phase is present up to near γ=0.14. The NaCl-type metastable phase becomes unstable with increased Sb2Te3; after subjecting the compound Ge8Sb2Te11 (γ=0.11) to heat treatment for 15 days at 773 K, a stable homologous structure appeared. [ABSTRACT FROM AUTHOR]

Published
2008
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13. Structural characteristics of GeTe-rich GeTe-[Sb.sub.2][Te.sub.3] pseudobinary metastable crystals

Author

Matsunaga, T., Morita, H., Kojima, R., Yamada, N., Kifune, K., Kubota, Y., Tabata, Y., Kim, J.-J., Kobata, M., Ikenaga, E., and Kobayashi, K.

Subjects
Germanium -- Structure, Germanium -- Thermal properties, Tellurium -- Structure, Tellurium -- Thermal properties, Antimony -- Structure, Antimony -- Thermal properties, Physics
Abstract

Several studies are conducted to explain the synthesis and structural characteristics of GeTe-rich GeTe-[Sb.sub.2][Te.sub.3] pseudobinary metastable crystals. An increase in the temperature is shown to lead to a change in the structure of the crystals from a slightly distorted NaCl-type structure to a regular type.

Published
2008

18. Identifying the Electronic Character and Role of the Mn States in the Valence Band of (Ga,Mn)As

Author

Fujii, J., primary, Salles, B. R., additional, Sperl, M., additional, Ueda, S., additional, Kobata, M., additional, Kobayashi, K., additional, Yamashita, Y., additional, Torelli, P., additional, Utz, M., additional, Fadley, C. S., additional, Gray, A. X., additional, Braun, J., additional, Ebert, H., additional, Di Marco, I., additional, Eriksson, O., additional, Thunström, P., additional, Fecher, G. H., additional, Stryhanyuk, H., additional, Ikenaga, E., additional, Minár, J., additional, Back, C. H., additional, van der Laan, G., additional, and Panaccione, G., additional

Published
2013
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20. Band offsets in complex-oxide thin films and heterostructures of SrTiO3/LaNiO3 and SrTiO3/GdTiO3 by soft and hard X-ray photoelectron spectroscopy

Author

Conti, G., primary, Kaiser, A. M., additional, Gray, A. X., additional, Nemšák, S., additional, Pálsson, G. K., additional, Son, J., additional, Moetakef, P., additional, Janotti, A., additional, Bjaalie, L., additional, Conlon, C. S., additional, Eiteneer, D., additional, Greer, A. A., additional, Keqi, A., additional, Rattanachata, A., additional, Saw, A. Y., additional, Bostwick, A., additional, Stolte, W. C., additional, Gloskovskii, A., additional, Drube, W., additional, Ueda, S., additional, Kobata, M., additional, Kobayashi, K., additional, Van de Walle, C. G., additional, Stemmer, S., additional, Schneider, C. M., additional, and Fadley, C. S., additional

Published
2013
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26. Identification of Different Electron Screening Behavior Between the Bulk and Surface of (Ga,Mn)As

Author

Fujii, J., primary, Sperl, M., additional, Ueda, S., additional, Kobayashi, K., additional, Yamashita, Y., additional, Kobata, M., additional, Torelli, P., additional, Borgatti, F., additional, Utz, M., additional, Fadley, C. S., additional, Gray, A. X., additional, Monaco, G., additional, Back, C. H., additional, van der Laan, G., additional, and Panaccione, G., additional

Published
2011
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37. Core-level electronic structure evolution of heavily boron-doped superconducting diamond studied with hard x-ray photoemission spectroscopy

Author

Yokoya, T., primary, Ikenaga, E., additional, Kobata, M., additional, Okazaki, H., additional, Kobayashi, K., additional, Takeuchi, A., additional, Awaji, A., additional, Takano, Y., additional, Nagao, M., additional, Sakaguchi, I., additional, Takenouchi, T., additional, Kawarada, H., additional, and Oguchi, T., additional

Published
2007
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39. Hard X-ray photoelectron spectroscopy on ultra shallow plasma-doped silicon layers

Author

Kobata, M., primary, Ikenaga, E., additional, Kim, J. J., additional, Yabashi, M., additional, Kobayashi, K., additional, Miwa, D., additional, Nishino, Y., additional, Tamasaku, K., additional, Ishikawa, T., additional, Jin, C. G., additional, Sasaki, Y., additional, Okashita, K., additional, Tamura, H., additional, Ito, H., additional, Mizuno, B., additional, and Okumura, T., additional

Published
2007
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47. Serum Cystatin C Is a More Sensitive Marker of Glomerular Function than Serum Creatinine

Author

Shimizu-Tokiwa, A., Kobata, M., Io, H., Kobayashi, N., Shou, I., Funabiki, K., Fukui, M., Horikoshi, S., Shirato, I., Saito, K., and Tomino, Y.

Abstract

AbstractWe determined the relationship between the levels of serum cystatin C or creatinine (s-Cr) and the grade of creatinine clearance (CCr) in patients with various glomerular diseases. Serum samples from 96 patients with glomerular diseases were obtained from our hospital. The levels of serum cystatin C were measured using the Dade Behring Cystatin C assay with the automated Dade Behring Nephelometer II (BNII). CCr levels were classified into six groups according to the Guidelines of the Japanese Society of Nephrology as follows: grade 1 (normal renal function); grade 2 (slight decrease of renal function); grade 3 (moderate decrease of renal function); grade 4 (severe decrease of renal function); grade 5 (renal failure), and grade 6 (uremia). The mean levels of serum cystatin C in grade 3 patients were significantly higher than those in grade 1. The mean levels of serum cystatin C in grades 4, 5 and 6 patients were also significantly higher than those in grade 1. However, the mean levels of serum Cr in grade 3 patients were not significantly higher than those in grade 1. The levels of s-Cr in grades 4, 5 or 6 patients were significantly higher than those in grade 1. In this study, an increase of serum cystatin C levels occurred earlier than that of s-Cr in various glomerular diseases. It appears that the levels of serum cystatin C may provide early prognostic marker of patients with various glomerular diseases rather than the levels of s-Cr. Copyright © 2002 S. Karger AG, Basel

Published
2002

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