アクチノイド化合物の新奇強磁性超伝導の探索と磁場誘起現象

2015 Fiscal Year Annual Research Report

• Project/Area Number: 25247055
• Research Institution: Tohoku University
• Principal Investigator: 青木 大 東北大学, 金属材料研究所, 教授 (30359541)
• Co-Investigator(Kenkyū-buntansha): 本多 史憲 東北大学, 金属材料研究所, 准教授 (90391268) ; 本間 佳哉 東北大学, 金属材料研究所, 助教 (00260448) ; 李 徳新 東北大学, 金属材料研究所, 助教 (40281985)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 強磁性 / 超伝導 / ウラン化合物

Outline of Annual Research Achievements

強磁性と超伝導は、通常は共存することができない。強磁性には強い内部磁場が働いており、超伝導電子対を破壊してしまうからである。理論的には、強磁性量子臨界点近傍で、スピン三重項による超伝導が予想されていたが、近年まで実験で明らかになった例はなかった。ウラン化合物であるUGe2で強磁性と超伝導の共存が初めて発見されて以降、これまでにURhGe、UCoGeの強磁性超伝導が発見されている。いずれもウラン化合物であり、5f電子系物質がきわめて興味深い物質群であることを示している。これら強磁性超伝導体の最も特徴的な性質は、高い超伝導上部臨界磁場Hc2である。本研究では、強磁性超伝導の性質を精密物性測定から明らかにすること、また高いHc2を含む磁場誘起現象を実験的に明らかにすることを目的として研究をすすめた。
本年度は、磁場あるいは圧力で誘起されたフェルミ面の不安定性とリフシッツ転移を、熱電能、磁気抵抗、ホール効果、ドハース・ファンアルフェン効果など、極限環境下における多数の実験手段を用いて多角的に研究をすすめた。その結果、URhGeにおいては磁場誘起超伝導を引き起こす要因となっているスピン再配列近傍でフェルミ面が大きく変わること、また弱い一次の転移が起きていることが明らかになった。また、UCoGeにおいては強磁性が抑制される臨界圧近傍でやはりフェルミ面の再構築が起きていることが分かった。強磁性超伝導体の特異な磁場誘起現象は、スピンゆらぎだけでなくフェルミ面のゆらぎも重要な役割を果たしていることが分かった。

Research Progress Status

27年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

27年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] CEA-Grenoble/CNRS/LNCMI(フランス)
  • Country Name: FRANCE
  • Counterpart Institution: CEA-Grenoble/CNRS/LNCMI
• [Journal Article] Field-Induced Lifshitz Transition without Metamagnetism in CeIrIn5 (2016)
  • Author(s): Aoki, D. Seyfarth, G. Pourret, A. Gourgout, A. McCollam, A. Bruin, J. A. N. Krupko, Y. Sheikin, I.
  • Journal Title: PHYSICAL REVIEW LETTERS Volume: 116 Pages: 037202-1-5
  • DOI: 10.1103/PhysRevLett.116.037202
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Pressure cell for transport measurements under high pressure and low temperature in pulsed magnetic fields (2016)
  • Author(s): Braithwaite, Daniel Knafo, William Settai, Rikio Aoki, Dai Kurahashi, Shuhei Flouquet, Jacques
  • Journal Title: REVIEW OF SCIENTIFIC INSTRUMENTS Volume: 87 Pages: 023907-1-5
  • DOI: 10.1063/1.4941714
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Properties and Collapse of the Ferromagnetism in UCo1-xRuxAl Studied in Single Crystals (2016)
  • Author(s): Pospisil, Jiri Opletal, Petr Valiska, Michal Tokunaga, Yo Stunault, Anne Haga, Yoshinori Tateiwa, Naoyuki Gillon, Beatrice Honda, Fuminori Yamamura, Tomoo Niznansky, Vojtech Yamamoto, Etsuji Aoki, Dai
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Volume: 85 Pages: 034710-1-10
  • DOI: 10.7566/JPSJ.85.034710
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Superconducting and Fermi Surface Properties of Single Crystal Zr2Co (2016)
  • Author(s): Teruya, Atsushi Kakihana, Masashi Takeuchi, Tetsuya Aoki, Dai Honda, Fuminori Nakamura, Ai Haga, Yoshinori Matsubayashi, Kazuyuki Uwatoko, Yoshiya Harima, Hisatomo Hedo, Masato Nakama, Takao Onuki, Yoshichika
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Volume: 85 Pages: 034706-1-10
  • DOI: 10.7566/JPSJ.85.034706
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Thermoelectric power quantum oscillations in the ferromagnet UGe2 (2016)
  • Author(s): A. Palacio Morales, A. Pourret, G. Knebel, G. Bastien, V. Taufour, D. Aoki, H. Yamagami, and J. FlouquetA. Palacio Morales, A. Pourret, G. Knebel, G. Bastien, V. Taufour, D. Aoki, H. Yamagami, and J. Flouquet
  • Journal Title: Phys. Rev. B Volume: 93 Pages: 155120-1-11
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Lattice dynamics of the heavy-fermion compound URu2Si2 (2015)
  • Author(s): J. Buhot, M. A. Measson, Y. Gallais, M. Cazayous, A. Sacuto, F. Bourdarot, S. Raymond, G. Lapertot, D. Aoki, L. P. Regnault, A. Ivanov, P. Piekarz, K. Parlinski, D. Legut, C. C. Homes, P. Lejay, R. P. S. M. Lobo
  • Journal Title: Phys. Rev. B Volume: 91 Pages: 035129-1-13
  • DOI: 10.1103/PhysRevB.91.035129
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Pressure-Temperature-Field Phase Diagram in the Ferromagnet U3P4 (2015)
  • Author(s): Araki, Shingo Hayashida, Minami Nishiumi, Naoto Manabe, Hiroki Ikeda, Yoichi Kobayashi, Tatsuo C. Murata, Keizo Inada, Yoshihiko Wisniewski, Piotr Aoki, Dai Onuki, Yoshichika Yamamoto, Etsuji Haga, Yoshinori
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Volume: 84 Pages: 024705-1-8
  • DOI: 10.7566/JPSJ.84.024705
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Uniaxial-Stress-Induced Ferromagnetism in the Itinerant Metamagnetic Compound UCoAl Probed by MagnetostrictionMeasurements (2015)
  • Author(s): Shimizu, Yusei Salce, Bernard Combier, Tristan Aoki, Dai Flouquet, Jacques
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Volume: 84 Pages: 023704-1-4
  • DOI: 10.7566/JPSJ.84.023704
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Large Cyclotron Effective Mass Detected by de Haas-van Alphen Effect in YbCu2Si2 (2015)
  • Author(s): Dai Aoki, Fuminori Honda, Yoshiya Homma, DeXin Li, Rikio Settai, Hisatomo Harima, Yoshichika Onuki
  • Journal Title: J. Phys. Soc. Jpn. Volume: 84 Pages: 035002-1-2
  • DOI: 10.7566/JPSJ.84.035002
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Unusual strong spin-fluctuation effects around the critical pressure of the itinerant Ising-type ferromagnet URhAl (2015)
  • Author(s): Shimizu, Yusei Braithwaite, Daniel Salce, Bernard Combier, Tristan Aoki, Dai Hering, Eduardo N. Ramos, Scheilla M. Flouquet, Jacques
  • Journal Title: PHYSICAL REVIEW B Volume: 91 Pages: 125115-1-9
  • DOI: 10.1103/PhysRevB.91.125115
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Reentrant Superconductivity Driven by Quantum Tricritical Fluctuations in URhGe: Evidence from Co-59 NMR in URh0.9Co0.1Ge (2015)
  • Author(s): Tokunaga, Y. Aoki, D. Mayaffre, H. Kraemer, S. Julien, M. -H. Berthier, C. Horvatic, M. Sakai, H. Kambe, S. Araki, S.
  • Journal Title: PHYSICAL REVIEW LETTERS Volume: 114 Pages: 216401-1-5
  • DOI: 10.1103/PhysRevLett.114.216401
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Fermi surface instabilities in CeRh2Si2 at high magnetic field and pressure (2015)
  • Author(s): Morales, A. Palacio Pourret, A. Seyfarth, G. Suzuki, M. -T. Braithwaite, D. Knebel, G. Aoki, D. Flouquet, J.
  • Journal Title: PHYSICAL REVIEW B Volume: 91 Pages: 245129-1-9
  • DOI: 10.1103/PhysRevB.91.245129
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Microscopic magnetic properties of the ferromagnetic superconductor UCoGe reviewed by x-ray magnetic circular dichroism (2015)
  • Author(s): Taupin, M. Sanchez, J. -P. Brison, J. -P. Aoki, D. Lapertot, G. Wilhelm, F. Rogalev, A.
  • Journal Title: PHYSICAL REVIEW B Volume: 92 Pages: 035124-1-6
  • DOI: 10.1103/PhysRevB.92.035124
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Optical conductivity of URu2Si2 in the Kondo liquid and hidden-order phases (2015)
  • Author(s): Lobo, R. P. S. M. Buhot, J. Measson, M. A. Aoki, D. Lapertot, G. Lejay, P. Homes, C. C.
  • Journal Title: PHYSICAL REVIEW B Volume: 92 Pages: 045129-1-9
  • DOI: 10.1103/PhysRevB.92.045129
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Quasi-two-dimensional Fermi surfaces of the heavy-fermion superconductor Ce2PdIn8 (2015)
  • Author(s): Goetze, K. Klotz, J. Gnida, D. Harima, H. Aoki, D. Demuer, A. Elgazzar, S. Wosnitza, J. Kaczorowski, D. Sheikin, I.
  • Journal Title: PHYSICAL REVIEW B Volume: 92 Pages: 115141-1-5
  • DOI: 10.1103/PhysRevB.92.115141
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Non-Fermi-liquid nature and exotic thermoelectric power in the heavy-fermion superconductor UBe13 (2015)
  • Author(s): Shimizu, Yusei Pourret, Alexandre Knebel, Georg Palacio-Morales, Alexandra Aoki, Dai
  • Journal Title: PHYSICAL REVIEW B Volume: 92 Pages: 241101(R)1-5
  • DOI: 10.1103/PhysRevB.92.241101
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Ferromagnetic superconductivity and Fermi surface instabilities (2016)
  • Author(s): D. Aoki
  • Organizer: Workshop: Anomalous Transport in Multipolar and Topological Materials
  • Place of Presentation: Baltimore, USA
  • Year and Date: 2016-03-11 – 2016-03-12
  • Int'l Joint Research / Invited
• [Presentation] f電子系化合物の純良単結晶育成と強磁性超伝導の最近の進展 (2015)
  • Author(s): 青木大
  • Organizer: 物性研短期研究会
  • Place of Presentation: 東京大学物性研究所
  • Year and Date: 2015-12-08 – 2015-12-09
  • Invited
• [Presentation] f電子系化合物の磁性と超伝導 (2015)
  • Author(s): 青木大
  • Organizer: 中性子プラットフォームによる物質材料科学の進展
  • Place of Presentation: 東北大学金属材料研究所
  • Year and Date: 2015-11-12 – 2015-11-13
• [Presentation] Recent advances in ferromagnetic superconductors (2015)
  • Author(s): D. Aoki
  • Organizer: M2S 2015
  • Place of Presentation: Geneva, Switzerland
  • Year and Date: 2015-08-23 – 2015-08-28
  • Int'l Joint Research
• [Presentation] Metamagnetism in heavy fermion systems (2015)
  • Author(s): G. Knebel, A. Pourret, D. Aoki, T. Combier, A. Palacio Morales, G. Lapertot, T. D. Matsuda, J. Flouquet
  • Organizer: 20th International Conference on Magnetism 2015
  • Place of Presentation: Barcelona, Spain
  • Year and Date: 2015-07-05 – 2015-07-10
  • Int'l Joint Research