Dopant ordering and enhancement of superconducting transition temperature induced by co-doping of iron-based superconductors

2012 Fiscal Year Final Research Report

• Project/Area Number: 23740274
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Okayama University
• Principal Investigator: KUDO Kazutaka 岡山大学, 大学院・自然科学研究科, 助教 (40361175)
• Project Period (FY): 2011 – 2012
• Keywords: 高温超伝導

Research Abstract

Iron-based superconductors consist of alternating two-dimensional Fe2As2layers and spacer layers. In order to realize higher transition temperature Tc, it is essential to seek novel spacer layers to optimize the electronic state in Fe2As2layer. The spacer layers reported so far consist of ionic chemical bonds. In this study, we discovered iron-based superconductors Ca10(PtnAs8)(Fe2-xPtxAs2)5(n = 3, 4) with PtnAs8spacer layers made of covalent chemical bonds. Tc= 17 K was observed in the beta phase (n = 3), in which Pt and vacancy are ordered in the spacer layer. By adjusting the amounts of Pt and vacancy, Tcwas raised up to 38 K in the alpha phase (n = 4). Our results demonstrated that a variety of spacer layers can be included in the iron-based superconductors.

Research Products

• [Journal Article] Emergence of superconductivity at 45 K by lanthanum and phosphorus co-doping of CaFe2As2 (2013)
  • Author(s): K. Kudo, K. Iba, M. Takasuga, Y. Kitahama, J. Matsumura, M. Danura, Y. Nogami, and M. Nohara
  • Journal Title: Scientific Reports Volume: 3 Pages: 1478 (5)
  • DOI: DOI:10.1038/srep01478
  • Peer Reviewed
• [Journal Article] Giant Phonon Softening and Enhancement of Superconductivity by Phosphorus Doping of BaNi2As2 (2012)
  • Author(s): K. Kudo, M. Takasuga, Y. Okamoto, Z. Hiroi, and M. Nohara
  • Journal Title: Physical Review Letters Volume: 109 Pages: 097002 (5)
  • DOI: DOI:10.1103/PhysRevLett.109.097002
  • Peer Reviewed
• [Journal Article] Iron-platinum-arsenide superconductors Ca10(PtnAs8)(Fe2-xPtxAs2)5 (2012)
  • Author(s): M. Nohara, S. Kakiya, K. Kudo, Y. Oshiro, S. Araki, T. C. Kobayashi, K. Oku, E. Nishibori, and H. Sawa
  • Journal Title: Solid State Communications Volume: 152 Pages: 635-639
  • DOI: DOI:10.1016/j.ssc.2011.12.034
  • Peer Reviewed
• [Journal Article] Breakdown of chemical scaling for Pt-doped CaFe2As2 (2012)
  • Author(s): K. Kudo, M. Kobayashi, S. Kakiya, M. Danura, and M. Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 81 Pages: 035002 (2)
  • DOI: DOI:10.1143/JPSJ.81.035002.
  • Peer Reviewed
• [Journal Article] Interplay of superconductivity and Fermi-liquid transport in Rh-doped CaFe2As2with lattice- collapse transition (2011)
  • Author(s): M. Danura, K. Kudo, Y. Oshiro, S. Araki, T. C. Kobayashi, and M. Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 80 Pages: 103701 (4)
  • DOI: DOI:10.1143/JPSJ.80.103701
  • Peer Reviewed
• [Journal Article] Superconductivity at 38 K in iron-based compound with platinum-arsenide layers Ca10(Pt4As8)(Fe2-xPtxAs2)5 (2011)
  • Author(s): S. Kakiya, K. Kudo, Y. Nishikubo, K. Oku, E. Nishibori, H. Sawa, T. Yamamoto, T. Nozaka, and M. Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 80 Pages: 093704 (4)
  • DOI: DOI:10.1143/JPSJ.80.093704
  • Peer Reviewed
• [Journal Article] Superconductivity in the honeycomb-lattice pnictide SrPtAs (2011)
  • Author(s): Y. Nishikubo, K. Kudo, and M. Nohara
  • Journal Title: Journal of the Physical Society of Japan Volume: 80 Pages: 055002 (2)
  • DOI: DOI:10.1143/JPSJ.80.055002
  • Peer Reviewed
• [Presentation] Chemical tuning of soft-phonons and enhancement of superconductivity in BaNi2As2 (2013)
  • Author(s): K. Kudo
  • Organizer: QS2C Theory Forum International Symposium on "Strongly Correlated Quantum Science"
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 20130126-29
• [Presentation] Electronic phase diagram of the iron-based superconductors Ca10(PtnAs8)(Fe2-xPtxAs2)5(n = 3, 4) with novel platinum-arsenide layers (2012)
  • Author(s): K. Kudo
  • Organizer: International Symposium on Physics and Chemistry of Novel Superconductors and Related Materials
  • Place of Presentation: Okayama, Japan
  • Year and Date: 20121001-03
• [Presentation] Superconductivity in the platinum-based arsenide SrPt2As2with a CaBe2Ge2-type structure (2012)
  • Author(s): K. Kudo
  • Organizer: M2S 2012 Materials & Mechanisms of Superconductivity Conference
  • Place of Presentation: Washington, D.C., USA
  • Year and Date: 20120729-0803
• [Presentation] Electronic phase diagram of the iron-platinum-based superconductors Ca10(Pt4As8)(Fe2-xPtxAs2)5and Ca10(Pt3As8)(Fe2-xPtxAs2)5 (2012)
  • Author(s): K. Kudo
  • Organizer: M2S 2012 Materials & Mechanisms of Superconductivity Conference
  • Place of Presentation: Washington, D.C., USA
  • Year and Date: 20120729-0803
• [Presentation] Interplay of Magnetic Fluctuation and Superconductivity in Ca(Fe1-xTMx)2As2(TM = Ru, Rh) with Lattice Collapse Transition (2012)
  • Author(s): K. Kudo
  • Organizer: 2012 MRS Spring Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 20120409-13
• [Presentation] Superconductivity at 38 K in Ca10(Pt4As8)(Fe2-xPtxAs2)5with Novel Platinum-Arsenide Layers (2012)
  • Author(s): K. Kudo
  • Organizer: 2012 MRS Spring Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 20120409-13
• [Presentation] 鉄白金系超伝導体Ca10(Pt4As8)(Fe2-xPtxAs2)5における超伝導転移温度のPt量依存性 (2012)
  • Author(s): 垣谷知美
  • Organizer: 日本物理学会第67回年次大会
  • Place of Presentation: 関西大学
  • Year and Date: 20120324-27
• [Presentation] Discovery of Iron-Platinum based Arsenide Superconductor with Transition Temperature 38 K (2012)
  • Author(s): K. Kudo
  • Organizer: UK-Japan Meeting 2012 in Tokyo
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 20120109-10
• [Presentation] 転移温度38Kを示す鉄白金系高温超伝導体の発見 (2011)
  • Author(s): 工藤一貴
  • Organizer: 「対称性の破れた凝縮系におけるトポロジカル量子現象」第2回 領域研究会
  • Place of Presentation: 岡山大学
  • Year and Date: 20111217-19
• [Presentation] Interplay of superconductivity and magnetic fluctuation in doped CaFe2As2with lattice collapse transition (2011)
  • Author(s): K. Kudo
  • Organizer: International Conference on Novel Superconductivity in Taiwan
  • Place of Presentation: Tainan, Taiwan
  • Year and Date: 20110804-09
• [Remarks] 2013年3月29日, 日刊工業新聞, 岡山大、鉄系物質で超電導転移温度を絶対温度45度に、5年ぶり最高値更新
• [Remarks] 2013年3月27日, 日経産業新聞, 安価な鉄で超電導物質 岡山大、加工容易な結晶
• [Remarks] 2012年11月9日, 山陽新聞, 電気抵抗ゼロ 高い移行温度 化合物軟化に成功
• [Remarks] 2012年10月1日, 日刊工業新聞, 岡山大など、ニッケル化合物がリン混合で転移温度5倍以上に上昇することを発見
• [Remarks] 2012年9月27日, 日経産業新聞, 臨界温度高める新手法 岡山大など 超電導材料、軟らかく
• [Remarks] 2011年10月7日, 科学新聞, 世界一複雑な原子配列を持つ高温超伝導体 岡山大、名大、東大の研究グループ発見
• [Remarks] 2011年9月26日, 日経産業新聞, 超電導物質 新しい鉄系発見 岡山大
• [Remarks]
  • URL: http://www.okayama-u.ac.jp/up_load_files/soumu-pdf/press23/press-110915-4.pdf
• [Remarks]
  • URL: http://www.okayama-u.ac.jp/up_load_files/soumu-pdf/press24/press-0920-7.pdf
• [Remarks]
  • URL: http://www.okayama-u.ac.jp/up_load_files/soumu-pdf/press24/press-0322-3.pdf