Development of strongly correlated multipole materials

2019 Fiscal Year Final Research Report

• Project Area: J-Physics: Physics of conductive multipole systems
• Project/Area Number: 15H05886
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: Okayama University
• Principal Investigator: NOHARA Minoru 岡山大学, 異分野基礎科学研究所, 教授 (70272531)
• Co-Investigator(Kenkyū-buntansha): 鬼丸 孝博 広島大学, 先端物質科学研究科, 教授 (50444708) ; 水口 佳一 首都大学東京, 理学研究科, 准教授 (50609865) ; 秋光 純 岡山大学, 異分野基礎科学研究所, 特任教授 (80013522) ; 播磨 尚朝 神戸大学, 理学研究科, 教授 (50211496)
• Project Period (FY): 2015-06-29 – 2020-03-31
• Keywords: J-Physics / 多極子伝導系 / スピン軌道結合 / 物質開発 / 超伝導

Outline of Final Research Achievements

We have developed model materials for observing novel phenomena caused by ordering, fluctuations, and delocalization of multipoles. The results include: (1) Development of new materials which exhibit large spin splitting of Fermi surfaces due to spatial inversion breaking and strong spin-orbit coupling. (2) Theoretical understanding of orbital crossing between spin split Fermi surfaces. (3) Synthesis of novel materials with conducting j-fermions. (4) Discovery of new materials with ordered honeycomb networks and observation of chiral superconductivity. (5) Experimental confirmation of single-site quadrupolar Kondo effect. (6) Discovery of superconductors which consist of Ir with a large SOC. (7) Discovery of Bi-based layered materials.

Free Research Field

固体物理学

Academic Significance and Societal Importance of the Research Achievements

多極子や局所対称性、スピン軌道結合に注目して、広範囲に物質探索と物質開発を進めたことで、30年以上前に理論的に予測されていた単サイトの四極子近藤効果が実験的に検証され、フェルミ面のスピン分裂や軌道交差が生じる典型物質が得られ、非従来型の超伝導や熱電現象が現れることが分かった。これよりj-フェルミオンという概念を創出し、遍歴する多極子研究の端緒を切り開いた。