Study on the critical fluctuations by the Hall effect and quantum oscillations measurements on heavy-fermion superconductors

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05544
• 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: Okayama University
• Principal Investigator: Araki Shingo 岡山大学, 自然科学研究科, 准教授 (90362615)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 高圧実験 / ホール効果 / 強相関電子系

Outline of Final Research Achievements

We determined the temperature-pressure phase diagram on CeRh2Si2 around the antiferromagnetic quantum critical pressure, 1 GPa. We observed two successive phase transitions, from the localized-antiferromagnetic phase to the itinerant-antiferromagnetic one , and from the itinerant-antiferromagnetic phase to the paramagnetic one. The A coefficient of the low-temperature resistivity increased at both phase boundaries, indicating the enhancement of the quantum fluctuations. The pressure-induced superconductivity appears in the itinerant-antiferromagnetic phase.
We observed the discontinuous change in the Hall coefficient on the antiferromagnet CeIn3, indicating the phase transition between the localized-antiferromagnetic phase and the itinerant-antiferromagnetic one. Although the quantum fluctuations increased around the localize-itinerant transition, the superconductivity was not observed.

Free Research Field

固体物理学

Academic Significance and Societal Importance of the Research Achievements

本研究ではCeRh2Si2とCeIn3において，反強磁性が絶対零度に抑制される磁気的量子臨界点だけではなく，反強磁性相内においてｆ電子の局在・遍歴転移の量子臨界点の存在とその周辺で量子ゆらぎが発達することを明らかにした。今後，他の重い電子系化合物においても同様の量子臨界点の探索と，量子ゆらぎをに起因する新奇電子状態の探索が期待される。