Variation of the superconducting order parameters in quasi-one-dimensional superconductors revealed by field-angle-resolved calorimetory under pressure

2013 Fiscal Year Final Research Report

• Project/Area Number: 23540407
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Kyoto University
• Principal Investigator: YONEZAWA Shingo 京都大学, 理学(系)研究科(研究院), 助教 (30523584)
• Project Period (FY): 2011 – 2013
• Keywords: 非従来型超伝導 / スピン三重項超伝導 / 磁気熱量効果 / 比熱 / 一軸性歪み / 一次相転移 / 超伝導ギャップ構造

Research Abstract

The purpose of this research project is to extract interesting properties of superconductors from thermodynamic measurements and from pressure experiments. In particular, by using sensitive calorimeters that we ourselves developed, we tried to discover phenomena that could not be resolved in previous studies.
The most important achievement of this project is the result of the magnetocaloric effect measurements of the spin-triplet superconductor Sr2RuO4. We found that at low temperatures the superconducting-normal state transition is of first order when the magnetic field is exactly parallel to the crystalline ab plane. This fact indicates that the superconductivity in this material is destroyed by unknown mechanism. In addition, we revealed the superconducting gap structure of the organic superconductor (TMTSF)2ClO4 from specific heat measurements. We furthermore investigated uniaxial strain effects on ruthenium oxides.

Research Products

• [Journal Article] Strong Increase of Tc of Sr2RuO4 Under Both Tensile and Compressive Strain (2014)
  • Author(s): C. W. Hicks, D. O. Brodsky, E. A. Yelland, A. S. Gibbs, J. A. N. Bruin, M. E. Barber, S. D. Edkins, K. Nishimura, S. Yonezawa, Y. Maeno, A. P. Mackenzie
  • Journal Title: Science Volume: 344 Pages: 283
  • DOI: 10.1126/science.1248292
  • Peer Reviewed
• [Journal Article] Anisotropic uniaxial pressure response of the Mott insulator Ca2RuO4 (2013)
  • Author(s): H. Taniguchi, K. Nishimura, R. Ishikawa, S. Yonezawa, S. K. Goh, F. Nakamura, Y. Maeno
  • Journal Title: Phys. Rev. B Volume: 88 Pages: 205111
  • DOI: 10.1103/PhysRevB.88.205111
  • Peer Reviewed
• [Journal Article] Extended analysis of the fieldangle-dependent heat capacity of (TMTSF) 2ClO4 toward identification of the superconducting gap structure (2013)
  • Author(s): S. Yonezawa, Y. Maeno D. Jérome
  • Journal Title: J. Phys. : Conf. Ser Volume: 449 Pages: 012032
  • DOI: 10.1088/1742-6596/449/1/012032
  • Peer Reviewed
• [Journal Article] First-Order Superconducting Transition of Sr2RuO4 (2013)
  • Author(s): S. Yonezawa, T. Kajikawa, Y. Maeno
  • Journal Title: Phys. Rev. Lett Volume: 110 Pages: 077003
  • DOI: 10.1103/PhysRevLett.110.077003
  • Peer Reviewed
• [Journal Article] Nodal superconducting order parameter and thermodynamic phase diagram of (TMTSF) 2ClO4 (2012)
  • Author(s): S. Yonezawa, Y. Maeno, K. Bechgaard, D. Jérome
  • Journal Title: Phys. Rev. B Volume: 85 Pages: 140502R
  • DOI: 10.1103/PhysRevB.85.140502
  • Peer Reviewed
• [Presentation] Sr2RuO4 の超伝導転移温度の面内一軸的歪み依存性 (2014)
  • Author(s): 西村佳悟, 米澤進吾, C. W. Hicks, D. O. Brodsky, A. P. Mackenzie, 前野悦輝
  • Organizer: 日本物理学会第69回年次大会
  • Place of Presentation: 東海大学
  • Year and Date: 2014-03-29
• [Presentation] Sr2RuO4の比熱や上部臨界磁場の内磁場異方性の増強 (2013)
  • Author(s): 米澤進吾, 梶川知宏, 前野悦輝
  • Organizer: 日本物理学会2013年秋季大会
  • Place of Presentation: 徳島大学
  • Year and Date: 2013-09-28
• [Presentation] Thermodynamic Evidence of the FirstOrder Superconducting Transition in Sr2RuO4 (2013)
  • Author(s): S. Yonezawa, T. Kajikawa, Y. Maeno
  • Organizer: The International Conference on Strongly Correlated Electron Systems (SCES2013)
  • Place of Presentation: 東京大学本郷キャンパス
  • Year and Date: 2013-08-07
• [Presentation] Sr2RuO4純良単結晶試料の交流比熱の磁場方向依存性 (2013)
  • Author(s): 梶川知宏, 米澤進吾, 前野悦輝
  • Organizer: 日本物理学会第68回年次大会
  • Place of Presentation: 広島大学東広島キャンパス
  • Year and Date: 2013-03-27
• [Presentation] 擬一次元超伝導体(TMTSF)2ClO4の磁場角度分解熱容量の詳細な解析 (2013)
  • Author(s): 米澤進吾
  • Organizer: 新学術領域研究「分子自由度が拓く新物質科学」第7回領域会議
  • Place of Presentation: 東京大学, 小柴ホール
  • Year and Date: 2013-03-03
• [Presentation] Anisotropic superconductivity in (TMTSF) 2ClO4 (2012)
  • Author(s): S. Yonezawa, Y. Maeno, K. Bechgaard, D. Jérome
  • Organizer: International Symposium on Materials Science Opened by Molecular Degrees of Freedom (MDF2012)
  • Place of Presentation: 宮崎シーガイア
  • Year and Date: 2012-12-03
• [Presentation] Sr2RuO4の微小単結晶の交流比熱測定 (2012)
  • Author(s): 米澤進吾, 梶川知宏, 前野悦輝
  • Organizer: 日本物理学会2012年秋季大会
  • Place of Presentation: 横浜国立大学
  • Year and Date: 2012-09-18
• [Presentation] Calorimetric study of unconventional superconductivity in (TMTSF) 2ClO4 (2012)
  • Author(s): S. Yonezawa, Y. Maeno, K. Bechgaard, D. Jérome
  • Organizer: International Conference on Materials and Mechanisms of Superconductivity (M2S2012)
  • Place of Presentation: Washington DC, USA
  • Year and Date: 2012-07-30
  • Invited
• [Presentation] Thermodynamic Study of Unconventional Superconductivity in the Bechgaard Salt (2012)
  • Author(s): S. Yonezawa, Y. Maeno, K. Bechgaard, D. Jérome
  • Organizer: International Conference on Science and Technology of Synthetic Metals 2012 (ICSM2012)
  • Place of Presentation: Atlanta, USA
  • Year and Date: 2012-07-12
  • Invited
• [Presentation] Anomalous Superconducting Transition of Sr2RuO4 Investigated by Magnetocaloric Effect (2012)
  • Author(s): S. Yonezawa, T. Kajikawa, Y. Maeno
  • Organizer: International Conference on Topological Quantum Phenomena (TQP2012)
  • Place of Presentation: 名古屋大学, ES 総合館
  • Year and Date: 2012-05-17
• [Presentation] Superconducting Phase Diagram of Sr2RuO4 Revealed by the Magnetocaloric Effect (2012)
  • Author(s): S. Yonezawa, T. Kajikawa, Y. Maeno
  • Organizer: UK-Japan Meettiing 2012
  • Place of Presentation: 東京大学, 小柴ホール・武田ホール
  • Year and Date: 2012-01-10
• [Presentation] Superconducting Gap Structure and Phase Diagram of (TMTSF) 2ClO4 (2011)
  • Author(s): S. Yonezawa, Y. Maeno, K. Bechgaard, D. Jérome
  • Organizer: The 9th International Symposium on Crystalline Organic Metals, Superconductors and Ferromagnets (ISCOM 2011)
  • Place of Presentation: Gniezno, Poland
  • Year and Date: 2011-09-27
  • Invited
• [Presentation] 擬一次元系超伝導(TMTSF)2ClO4の回転磁場中熱容量測定と超伝導ギャップ構造 (2011)
  • Author(s): 米澤進吾, 前野悦輝, Klaus Bechgaard, Denis Jérome
  • Organizer: 日本物理学会2011年秋季大会
  • Place of Presentation: 富山大学
  • Year and Date: 2011-09-23
• [Remarks]
  • URL: http://www.ss.scphys.kyotou.ac.jp/person/yonezawa/index.html
• [Remarks] アウトリーチ活動
• [Remarks] 2011-2013年度京都府立嵯峨野高等学校学校評議員
• [Remarks] 2011-2013年度京都物理コンテスト運営委員
• [Remarks] 2011-2013年度京都大学オープンキャンパス に参加
• [Remarks] 2012年度「最先端科学の体験型学習講座」Experienced-based Learning Course for Advanced Science(ELCAS)担当
• [Remarks] 報道関連
• [Remarks] プレスリリース「ルテニウム酸化物における超伝導の一次相転移の発見-超伝導と磁場の未知の相互作用メカニズムの存在を示唆-」(京都大学ホームページ, 2013年2月15日)
• [Remarks] 新聞報道「京大, ルテニウム酸化物の超電導で「一次相転移」を確認」(日刊工業新聞, 2013年2月20日朝刊25面)