Theoretical Study for Anomalous Properties due to Fluctuations of Non-magnetic Degrees of Freedom

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K05555
• 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: Osaka University
• Principal Investigator: Miyake Kazumasa 大阪大学, 大学院理学研究科, 招へい教授 (90109265)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 量子臨界価数転移 / 原子価スキッピング / 電荷近藤効果 / ４極子近藤効果

Outline of Final Research Achievements

In order to clarify the origin of unconventional physical phenomena originate from the fluctuations of non-magnetic local degrees of freedom, such as valence and electric quadrupole moment, three subjects were investigated. Namely, "quantum critical phenomena of valence transition", "charge Kondo effect",and "electric quadrupole fluctuations" were investigated theoretically. As a result, new insights were obtained as explicitly discussed below. These achievements were reported in international conferences (20) and domestic conferences (31),in which 14 resentations were invited talks.

Free Research Field

物性物理

Academic Significance and Societal Importance of the Research Achievements

価数ゆらぎに（Valence Fluctuations）関する物理の研究は、20世紀後半に多くの研究の蓄積はあったが、それは主に静的性質に関するものであった。21世紀に入るころから、価数の２次的相転移に伴う臨界ゆらぎが電気抵抗や比熱の温度依存性を始めとするとする様々な物性に非自明な振舞いを生じることが次第に分かってきた。この研究分野は、20世紀を通じて多くの研究成果が蓄積されてきた磁性研究の分野に比べると研究の発展段階は初期の段階にあったと言える。本基盤研究（C)では、価数ゆらぎの物理をより広く「非磁性自由度のゆらぎ」に起因する異常物性を解明するという点に学術的意義がある。