研究者詳細 - 村岡　祐治

論文 - 村岡　祐治

分割表示 184 件中 41 - 60 件目／全件表示 >>

Determination of the local structure of CsBi4-xPbxTe6 (x=0, 0.5) by X-ray absorption spectroscopy 査読

Takanori Wakita, Eugenio Paris, Takashi Mizokawa, Muammer Yasin Hacisalihoglu, Kensei Terashima, Hiroyuki Okazaki, Olivier Proux, Isabelle Kieffer, Eric Lahera, William Del Net, Luca Olivi, Yoshihiko Takano, Yuji Muraoka, Takayoshi Yokoya, Naurang L. Saini

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 18 ( 36 ) 25136 - 25142 2016年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

We have studied the local structure and valence electronic unoccupied states of thermoelectric CsBi4Te6 and superconducting CsBi3.5Pb0.5Te6 (T-c similar to 3 K) by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) measurements. The Bi-L-3 edge EXAFS reveals wide Bi-Te distance distribution for both compounds indicating complex atomic arrangements in the studied system. The mean square relative displacements (MSRDs) of the Bi-Te bond distances appear largely increased in Pb substituted system due to larger overall local disorder, however, one of the Bi-Te bonds shows a reduced disorder. On the other hand, the Bi-L-3 edge XANES is hardly affected by Pb substitution while the Te-L-1 edge XANES reveals increased density of unoccupied Te 5p states. This suggests that the carriers introduced by the Pb substitution in CsBi4-xPbxTe6 preferentially goes on Te sites. Similarly, the Cs-L-3 edge XANES also shows small changes due to Pb-substitution and reduced local disorder indicated by the reduced width of the Cs-L3 edge white line. We have also shown that the X-ray photoemission spectroscopy (XPS) measurements on various electronic core levels are in a qualitative agreement with the XANES results. These findings are consistent with carrier doping and a reduced disorder in one direction to be likely factors to drive the thermoelectric CsBi4Te6 into a bulk superconductor by Pb-substitution in CsBi4-xPbxTe6.

DOI： 10.1039/c6cp04949d

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Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor 査読

Masanori Sunagawa, Kensei Terashima, Takahiro Hamada, Hirokazu Fujiwara, Tetsushi Fukura, Aya Takeda, Masashi Tanaka, Hiroyuki Takeya, Yoshihiko Takano, Masashi Arita, Kenya Shimada, Hirofumi Namatame, Masaki Taniguchi, Katsuhiro Suzuki, Hidetomo Usui, Kazuhiko Kuroki, Takanori Wakita, Yuji Muraoka, Takayoshi Yokoya

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 85 ( 7 ) 073704 2016年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PHYSICAL SOC JAPAN

One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (T-c). In the early days, based on a weak-coupling viewpoint, the nesting between hole-and electron-like Fermi surfaces (FSs) leading to the so-called s +/- state was considered to be one such key feature. However, this theory has faced a serious challenge ever since the discovery of alkali-metal-doped FeSe (AFS) superconductors, in which only electron-like FSs with a nodeless superconducting gap are observed. Several theories have been proposed, but a consistent understanding is yet to be achieved. Here we show experimentally that a hole-like band exists in KxFe2-ySe2, which presumably forms a hole-like Fermi surface. The present study suggests that AFS can be categorized in the same group as iron arsenides with both hole- and electron-like FSs present. This result provides a foundation for a comprehensive understanding of the superconductivity in iron-based superconductors.

DOI： 10.7566/JPSJ.85.073704

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Local electronic state in the half-metallic ferromagnet CrO2 investigated by site-selective Cr-53 NMR measurements 査読

Hikaru Takeda, Yasuhiro Shimizu, Yoshiaki Kobayashi, Masayuki Itoh, Takaaki Jin-no, Masahiko Isobe, Yutaka Ueda, Sho Yoshida, Yuji Muraoka, Takayoshi Yokoya

PHYSICAL REVIEW B 93 ( 23 ) 235129 2016年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

We have made Cr-53 NMR measurements on polycrystalline and single-crystalline film samples to study the local electronic state of a half-metallic ferromagnet CrO2 which has the rutile structure with one crystallographically equivalent Cr site. We observe two kinds of Cr-53 NMR spectra in the ferromagnetic state of both the samples. An analysis on the hyperfine field shows the presence of two Cr sites with different orbital occupancies, suggesting that a local orbital order takes place with breaking the local symmetry in the rutile structure. This may be ascribed to the negative charge transfer between chromium and oxygen ions.

DOI： 10.1103/PhysRevB.93.235129

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Preparation of TaO2 thin films using NbO2 template layers by a pulsed laser deposition technique 査読

Y. Muraoka, Y. Fujimoto, M. Kameoka, Y. Matsuura, M. Sunagawa, K. Terashima, T. Wakita, T. Yokoya

599 125 - 132 2016年1月

Bulk sensitive angle-resolved photoelectron spectroscopy on Nd(O,F)BiS2 査読

K. Terashima, J. Sonoyama, M. Sunagawa, H. Fujiwara, T. Nagayama, T. Muro, M. Nagao, S. Watauchi, I. Tanaka, H. Okazaki, Y. Takano, Y. Mizuguchi, H. Usui, K. Suzuki, K. Kuroki, T. Wakita, Y. Muraoka, T. Yokoya

TMU INTERNATIONAL SYMPOSIUM ON NEW QUANTUM PHASES EMERGING FROM NOVEL CRYSTAL STRUCTURE 683 0012003 2016年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IOP PUBLISHING LTD

Bulk electronic structure of novel layered superconductor Nd(O,F)BiS2 was studied by using soft x-ray angle-resolved photoelectron spectroscopy (ARPES). Electron-like Fermi surface centered at the X(R) point was observed, consistent with earlier ARPES reports on surface-sensitive VUV light source. Based on the comparison of the electronic structure between Nd(O,F)BiS2 and La(O,F)BiS2, we discuss possible important factors for the superconductivity in this series of material.

DOI： 10.1088/1742-6596/683/1/012003

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Comparative ARPES studies of LaOxF1−xBiS2 (x = 0.23 and 0.46) 査読

K. Terashima, T. Wakita, M. Sunagawa, H. Fujiwara, T. Nagayama, K. Ono, H. Kumigashira, M. Nagao, S. Watauchi, I. Tanaka, H. Okazaki, Y. Takano, Y. Mizuguchi, H. Usui, K. Kuroki, Y. Muraoka, T. Yokoya

J. Phys.: Conf. Ser. 683 012002 2016年

19aBP-1 熱電変換物質SnSeの角度分解光電子分光

永山貴将, 寺嶋健成, 田中将嗣, 小木曽理, 高野義彦, 森仁志, 臼井秀知, 黒木和彦, 脇田高徳, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 71 1441 - 1441 2016年

19pAJ-1 ハーフメタルCrO_2(001)膜表面の金属性

藤原弘和, 砂川正典, 寺嶋健成, 永山貴将, 橘高朋子, 尾形誠, 出田真一郎, 田中清尚, 脇田高徳, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 71 2492 - 2492 2016年

21pBN-6 Sr_<2-x>La_xIrO_4の角度分解光電子分光

寺嶋健成, 濱田貴裕, 砂川正典, 藤原弘和, 藤井政徳, 堀金和正, 小林夏野, 堀江理恵, 秋光純, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 71 2315 - 2315 2016年

Intrinsic spin polarized electronic structure of CrO2 epitaxial film revealed by bulk-sensitive spin-resolved photoemission spectroscopy 査読

Hirokazu Fujiwara, Masanori Sunagawa, Kensei Terashima, Tomoko Kittaka, Takanori Wakita, Yuji Muraoka, Takayoshi Yokoya

APPLIED PHYSICS LETTERS 106 ( 20 ) 202404 2015年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

We have performed bulk-sensitive spin-resolved photoemission spectroscopy in order to clarify the intrinsic spin-resolved electronic states of half-metallic ferromagnet CrO2. We used CrO2 epitaxial films on TiO2(100), which shows a peak at 1 eV with a clear Fermi edge, consistent with the bulk-sensitive PES spectrum for CrO2. In spin-resolved spectra at 40 K, while the Fermi edge was observed in the spin up (majority spin) state, no states at the Fermi level (EF) with an energy gap of 0.5 eV below EF were observed in the spin down (minority spin) state. At 300 K, the gap in the spin down state closes. These results are consistent with resistivity measurements and magnetic hysteresis curves of the fabricated CrO2 film, constituting spectroscopic evidence for the half-metallicity of CrO2 at low temperature and reducing the spin polarization at room temperature. We also discuss the electron correlation effects of Cr 3d. (C) 2015 AIP Publishing LLC.

DOI： 10.1063/1.4921629

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Comparative ARPES Study on Iron–Platinum–Arsenide Superconductor Ca10(Pt4As8)(Fe2−xPtxAs2)5 (x = 0.25 and 0.42) 査読

Masanori Sunagawa, Rikiya Yoshida, Toshihiko Ishiga, Koji Tsubota, Taihei Jabuchi, Junki Sonoyama, Satomi Kakiya, Daisuke Mitsuoka, Kazutaka Kudo, Minoru Nohara, Kanta Ono, Hiroshi Kumigashira, Tamio Oguchi, Takanori Wakita, Yuji Muraoka, Takayoshi Yokoya

J. Phys. Soc. Jpn. 84 ( 5 ) 055001 2015年5月

Signature of high T-c above 25 K in high quality superconducting diamond 査読

Hiroyuki Okazaki, Takanori Wakita, Takayuki Muro, Tetsuya Nakamura, Yuji Muraoka, Takayoshi Yokoya, Shin-ichiro Kurihara, Hiroshi Kawarada, Tamio Oguchi, Yoshihiko Takano

APPLIED PHYSICS LETTERS 106 ( 5 ) 052601 2015年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

We have observed zero resistivity above 10K and an onset of resistivity reduction at 25.2K in a heavily B-doped diamond film. However, the effective carrier concentration is similar to that of superconducting diamond with a lower T-c. We found that the carrier has a longer mean free path and lifetime than in the previous report, indicating that this highest T-c diamond has better crystallinity compared to that of other superconducting diamond films. In addition, the susceptibility shows a small transition above 20K in the high quality diamond, suggesting a signature of superconductivity above 20 K. These results strongly suggest that heavier carrier doped defect-free crystalline diamond could give rise to high T-c diamond. (C) 2015 AIP Publishing LLC.

DOI： 10.1063/1.4907411

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Signature of high $T_c$ around 25K in higher quality heavily boron-doped diamond 査読

H. Okazaki, T. Wakita, T. Muro, T. Nakamura, Y. Muraoka, T. Yokoya, S. Kurihara, H. Kawarada, T. Oguchi, Y. Takano

Appl. Phys. Lett. 2015年2月

18pCH-1 バルク敏感スピン分解光電子分光による強磁性金属CrO_2 の本質的な電子状態の解明

藤原弘和, 砂川正典, 寺嶋健成, 橘高朋子, 尾形誠, 脇田高徳, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 942 - 942 2015年

16pDA-7 Ln(O,F)BiS_2におけるフェルミ面形状と化学圧力効果 : 角度分解光電子分光

寺嶋健成, 脇田高徳, 砂川正典, 藤原弘和, 濱田貴裕, 長尾雅則, 綿打敏司, 田中功, 小野寛太, 組頭広志, 岡崎宏之, 高野義彦, 臼井秀知, 黒木和彦, 鈴木雄大, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 1720 - 1720 2015年

16aDB-6 K_xFe_<2-y>Se_2の角度分解光電子分光II

砂川正典, 寺嶋健成, 濱田貴裕, 藤原弘和, 福良哲司, 竹田彩, 田中将嗣, 竹屋浩幸, 高野義彦, 有田将司, 島田賢也, 生天目博文, 谷口雅樹, 鈴木雄大, 臼井秀知, 黒木和彦, 脇田高徳, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 1681 - 1681 2015年

16aAD-4 複鉄酸化物YbFe_2O_4のFe 3p-3d共鳴光電子分光

福良哲司, 脇田高徳, 竹田彩, 寺嶋健成, 藤原孝将, 池田直, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 2405 - 2405 2015年

17pCD-9 Ce(Os_<1-y>Re_y)_2Al_<10>の高分解能光電子分光

永山貴将, 寺嶋健成, 川端丈, 山田義大, 高畠敏郎, 脇田高徳, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 1933 - 1933 2015年

18aCE-9 高濃度ボロンドープダイヤモンド超伝導のB1s-2p共鳴光電子分光

竹田彩, 脇田高徳, 福良哲司, 高野義彦, 栗原慎一郎, 川原田洋, 小口多美夫, 村岡祐治, 横谷尚睦

日本物理学会講演概要集 70 1237 - 1237 2015年

Proximity to Fermi-surface topological change in superconductingLaO0.54F0.46BiS2 査読

Kensei Terashima, Junki Sonoyama, Takanori Wakita, Masanori Sunagawa, Kanta Ono, Hiroshi Kumigashira, Takayuki Muro, Masanori Nagao, Satoshi Watauchi, Isao Tanaka, Hiroyuki Okazaki, Yoshihiko Takano, Osuke Miura, Yoshikazu Mizuguchi, Hidetomo Usui, Katsuhiro Suzuki, Kazuhiko Kuroki, Yuji Muraoka, Takayoshi Yokoya

90 ( 22 ) 220512(R) 2014年12月

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