Exploration of chiral d-wave superconducting states in honeycomb-lattice compounds with van Hove singularity

2018 Fiscal Year Annual Research Report

• Project/Area Number: 16K05451
• Research Institution: Okayama University
• Principal Investigator: 工藤 一貴 岡山大学, 異分野基礎科学研究所, 准教授 (40361175)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: カイラル超伝導 / ハニカム構造

Outline of Annual Research Achievements

本研究では、時間反転対称性を破る新奇な超伝導状態であるカイラル超伝導状態の探索を進めている。前年度、本研究で発見したハニカム構造を持つ新超伝導体のミュオンスピン回転／緩和実験を行い、超伝導状態において自発磁場発生の兆候を捉えた。その結果は、時間反転対称性の破れた超伝導状態を示唆する。結晶構造の対称性から、その有力な候補として２つのd波対称性が混成して生じるカイラルd波の超伝導状態が挙げられた。平成３０年度は、当該新超伝導体において示唆されたカイラルd波超伝導状態に関する検証を進めた。
(1) 不純物置換を行うと当該新超伝導体の超伝導転移温度が大きく変化することが分かった。その際、電子状態密度とデバイ温度がほとんど変化しなかったことから、当該物質が示す超伝導が少なくとも電子格子相互作用で説明できないことが明らかになった。(2) これまでに行ったミュオンスピン回転／緩和実験の詳細なデータ解析を進め、ミュオンスピン緩和率の物質依存性を調べた。その結果、時間反転対称性の破れた超伝導状態を示唆するミュオンスピン緩和率の増大が、不純物置換によって完全に抑制されることが明らかになった。(3) 第一原理計算を行いバンド構造を調べた結果、フェルミ準位近傍におけるファンホーブ特異性と、ネスティングが比較的良いフェルミ面が示唆された。これらの実験とバンド計算の結果は全て、カイラルd波超伝導発現と矛盾しない。

Research Products

• [Int'l Joint Research] Canadian Light Source/University of Toronto(カナダ)
  • Country Name: CANADA
  • Counterpart Institution: Canadian Light Source/University of Toronto
• [Int'l Joint Research] Max Planck Institute/Philipps-University Marburg(ドイツ)
  • Country Name: GERMANY
  • Counterpart Institution: Max Planck Institute/Philipps-University Marburg
• [Int'l Joint Research] University of Leeds(英国)
  • Country Name: UNITED KINGDOM
  • Counterpart Institution: University of Leeds
• [Int'l Joint Research] Italian Institute of Technology/Universita di Roma “La Sapienza”(イタリア)
  • Country Name: ITALY
  • Counterpart Institution: Italian Institute of Technology/Universita di Roma “La Sapienza”
• [Int'l Joint Research] CELLS - ALBA/ICMM, CSIC(スペイン)
  • Country Name: SPAIN
  • Counterpart Institution: CELLS - ALBA/ICMM, CSIC
• [Int'l Joint Research]
  • # of Other Countries: 1
• [Journal Article] Metastable Superconductivity in Two-Dimensional IrTe2 Crystals (2018)
  • Author(s): Masaro Yoshida, Kazutaka Kudo, Minoru Nohara, and Yoshihiro Iwasa
  • Journal Title: Nano Letters Volume: 18 Pages: 3113～3117
  • DOI: 10.1021/acs.nanolett.8b00673
  • Peer Reviewed
• [Journal Article] Superconductivity in BaPtSb with an Ordered Honeycomb Network (2018)
  • Author(s): Kazutaka Kudo, Yuki Saito, Takaaki Takeuchi, Shin-ya Ayukawa, Takayuki Kawamata, Shinichiro Nakamura, Yoji Koike, and Minoru Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 87 Pages: 063702(1~2)
  • DOI: 10.7566/JPSJ.87.063702
  • Peer Reviewed
• [Journal Article] Commensurate versus incommensurate charge ordering near the superconducting dome in Ir1?xPtxTe2 revealed by resonant x-ray scattering (2018)
  • Author(s): K. Takubo, K. Yamamoto, Y. Hirata, H. Wadati, T. Mizokawa, R. Sutarto, F. He, K. Ishii, Y. Yamasaki, H. Nakao, Y. Murakami, G. Matsuo, H. Ishii, M. Kobayashi, K. Kudo, and M. Nohara
  • Journal Title: Physical Review B Volume: 97 Pages: 205142(1~9)
  • DOI: 10.1103/PhysRevB.97.205142
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Superconductivity in Hexagonal BaPtAs: SrPtSb- and YPtAs-type Structures with Ordered Honeycomb Network (2018)
  • Author(s): Kazutaka Kudo, Takaaki Takeuchi, Hiromi Ota, Yuki Saito, Shin-ya Ayukawa, Kazunori Fujimura, and Minoru Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 87 Pages: 073708(1～5)
  • DOI: 10.7566/JPSJ.87.073708
  • Peer Reviewed
• [Journal Article] Ultrafast dissolution and creation of bonds in IrTe2induced by photodoping (2018)
  • Author(s): Shin-ichiro Ideta, Dongfang Zhang, Arend G. Dijkstra, Sergey Artyukhin, Sercan Keskin, Roberto Cingolani, Takahiro Shimojima, Kyoko Ishizaka, Hiroyuki Ishii, Kazutaka Kudo, Minoru Nohara, and R. J. Dwayne Miller
  • Journal Title: Science Advances Volume: 4 Pages: eaar3867(1～7)
  • DOI: 10.1126/sciadv.aar3867
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Development and application of 2.5 GPa-25 T high-pressure high-field electron spin resonance system using a cryogen-free superconducting magnet (2018)
  • Author(s): T. Sakurai, S. Kimura, M. Kimata, H. Nojiri, S. Awaji, S. Okubo, H. Ohta, Y. Uwatoko, K. Kudo, and Y. Koike
  • Journal Title: Journal of Magnetic Resonance Volume: 296 Pages: 1～4
  • DOI: 10.1016/j.jmr.2018.08.005
  • Peer Reviewed
• [Journal Article] Temperature-dependent local structure and superconductivity of BaPd2As2 and SrPd2As2 (2018)
  • Author(s): K. Terashima, E. Paris, L. Simonelli, E. Salas-Colera, A. Puri, T. Wakita, Y. Yamada, S. Nakano, H. Idei, K. Kudo, M. Nohara, Y. Muraoka, T. Mizokawa, T. Yokoya, and N. L. Saini
  • Journal Title: Physical Review B Volume: 98 Pages: 094525(1~5)
  • DOI: 10.1103/PhysRevB.98.094525
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Ultrathin Bismuth Film on High-Temperature Cuprate Superconductor Bi2Sr2CaCu2O8+δ as a Candidate of a Topological Superconductor (2018)
  • Author(s): Natsumi Shimamura, Katsuaki Sugawara, Sukrit Sucharitakul, Seigo Souma, Katsuya Iwaya, Kosuke Nakayama, Chi Xuan Trang, Kunihiko Yamauchi, Tamio Oguchi, Kazutaka Kudo, Takashi Noji, Yoji Koike, Takashi Takahashi, Tetsuo Hanaguri, and Takafumi Sato
  • Journal Title: ACS Nano Volume: 12 Pages: 10977～10983
  • DOI: 10.1021/acsnano.8b04869
  • Peer Reviewed
• [Journal Article] Atomic Imaging of Iron-Based Superconductor Parent FeTe Using X-Ray Fluorescence Holography (2018)
  • Author(s): Benedict Paulus, Shinya Hosokawa, Jens Rudiger Stellhorn, Benjamin Klee, Katarzyna M. Sowa, Kazutaka Kudo, Naoki Nishimoto, HiromiOta, Minoru Nohara, Marc de Boissieu, Nils Blanc, Nathalie Boudet, and Wolf-Christian Pilgrim
  • Journal Title: physica status solidi (b) Volume: 255 Pages: 1800200(1～5)
  • DOI: 10.1002/pssb.201800200
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Superconductivity and polymorphism in Pt and Pd pnictides (2019)
  • Author(s): K. Kudo
  • Organizer: RIIS Mini-workshop on Exploration of Novel Energy Materials
  • Int'l Joint Research
• [Presentation] Superconductivity in Pt-based pnictides with ordered honeycomb networks (2019)
  • Author(s): K. Kudo
  • Organizer: International Meeting on Study of Matter at Extreme Conditions (SMEC2019)
  • Int'l Joint Research / Invited
• [Presentation] Superconductivity in hexagonal BaPtAs and BaPtSb with an ordered honeycomb network (2018)
  • Author(s): K. Kudo, T. Takeuchi, H. Ota, Y. Saito, S. Ayukawa, K. Fujimura, T. Kawamata, S. Nakamura, Y. Koike, and M. Nohara
  • Organizer: J-Physics：多極子伝導系の物理 平成30年度領域全体会議
• [Presentation] Superconductivity and polymorphism in hexagonal BaPtAs with an ordered honeycomb network (2018)
  • Author(s): K. Kudo, T. Takeuchi, Y. Saito, H. Ota, and M. Nohara
  • Organizer: J-Physics 2018: International Workshop on New Materials and Crystal Growth
  • Int'l Joint Research
• [Presentation] Superconductivity in Novel Hexagonal BaPtAs with an Ordered Honeycomb Network (2018)
  • Author(s): K. Kudo, T. Takeuchi, H. Ota, and M. Nohara
  • Organizer: The 12th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (M2S2018)
  • Int'l Joint Research
• [Presentation] 秩序型ハニカム構造を持つ六方晶BaPtAsの超伝導 (2018)
  • Author(s): 工藤一貴, 竹内貴亮, 太田弘道, 齋藤有紀, 鮎川晋也, 藤村一徳, 野原実
  • Organizer: 日本物理学会2018年秋季大会
• [Presentation] Superconductivity and polymorphism in hexagonal Pt-based pnictides (2018)
  • Author(s): K. Kudo
  • Organizer: 2018 E-MRS Fall Meeting
  • Int'l Joint Research / Invited
• [Presentation] 秩序型ハニカム構造を持つ新超伝導体BaPtAsとBaPtSbの発見 (2018)
  • Author(s): 工藤一貴，竹内貴亮，齋藤有紀，野原実
  • Organizer: 第１２回物性科学領域横断研究会（領域合同研究会）
• [Presentation] Superconductivity in hexagonal BaPtAs with an ordered honeycomb network (2018)
  • Author(s): K. Kudo, T. Takeuchi, Y. Saito, and M. Nohara
  • Organizer: International Workshop on j-fermion Physics and Materials
  • Int'l Joint Research
• [Presentation] Ptニクタイドの結晶多形と超伝導 (2018)
  • Author(s): 工藤一貴，竹内貴亮，齋藤有紀，野原実
  • Organizer: 東京大学物性研究所 短期研究会「量子多体効果が生み出す液晶的電子状態」
• [Presentation] Discovery of Superconductivity in BaPtSb with a Noncentrosymmetric Structure (2018)
  • Author(s): Y. Saito, K. Kudo, T. Takeuchi, S. Ayukawa, T. Kawamata, S. Nakamura, Y. Koike, and M. Nohara
  • Organizer: The 12th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (M2S2018)
  • Int'l Joint Research
• [Presentation] 秩序型ハニカム構造を持つBaPtSbの超伝導 (2018)
  • Author(s): 齋藤有紀, 工藤一貴, 竹内貴亮, 鮎川晋也, 川股隆行, 中村慎一郎, 小池洋二, 野原実
  • Organizer: 日本物理学会2018年秋季大会
• [Remarks] 新しい超電導体を作り出す~電気抵抗ゼロの世界~
  • URL: https://www.okayama-u.ac.jp/up_load_files/press30/press-180531-5.pdf