Search for unique materials of charge Kondo effect and novel superconductivity

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K18734
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Osaka University
• Principal Investigator: Mukuda Hidekazu 大阪大学, 基礎工学研究科, 准教授 (90323633)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 核磁気共鳴 / 超伝導 / 電子局所自由度 / 近藤効果

Outline of Final Research Achievements

We have studied novel physical properties that emerge when the local degrees of freedom of valences derived from the valence skip phenomenon are hybridized with conduction electron systems. An anomalous increase in the nuclear magnetic relaxation rate was observed at low temperatures in the case of Tl-doped PbTe, which is most promising candidate that may skip valences. As a result of comparative verification with the case of various dopants, it was found that anomalies in the electronic state are observed only when the dopant is Tl. It suggests this phenomena is very rare. We plan to continue to research anomalous materials with physical properties that are emerged when the fluctuation of the local degree of freedom of electrons.

Free Research Field

超伝導

Academic Significance and Societal Importance of the Research Achievements

縮退した局在スピンと伝導電子の混成によって解明された近藤効果から半世紀を経た今、スピン以外の自由度が巨大な伝導電子の集団と混成したときに現れる新しいタイプの近藤効果が注目されている。本研究において、原子価スキップ現象による複数の価数(電荷)自由度が伝導電子と混成した電子状態揺らぎの異常を、核磁気共鳴を用いたミクロな視点から世界で初めて明らかにした。原子価スキップ現象が関連した現象はまだ未開拓の領域であり、本研究の萌芽的な成果は今後この現象が起因となる新しい超伝導機構の存在や熱電性能を向上させる可能性など、物性物理学の新概念を創出する可能性があり、今後のさらなる発展が期待される。