Low-temperature thermal expansion in a diluted Ce system exhibiting the Kondo effect

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K22332
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: University of Hyogo
• Principal Investigator: Yamane Yu 兵庫県立大学, 理学研究科, 助教 (80883511)
• Project Period (FY): 2020-09-11 – 2022-03-31
• Keywords: 強相関電子系 / セリウム化合物 / 近藤効果 / 熱膨張

Outline of Final Research Achievements

To reveal behaviors of thermal expansion when a ground state changes from the heavy Fermion state to the Kondo state, we measured the thermal expansion in a Kondo alloy La1-xCexCu6.A jump observed in x=1 at 215 K, which is attributed to a structural transition, shifts to 260 K with decreasing x to 0.6. This increase is consistent with the results of previous neutron scattering experiments. On the other hand, volume thermal expansions normalized with the Ce concentration x agree well. This result implies that the heavy Fermion state and the Kondo state give rise to similar thermal expansion.

Free Research Field

強相関電子系

Academic Significance and Societal Importance of the Research Achievements

希土類金属間化合物の熱膨張は、重い電子状態、量子臨界点近傍での非フェルミ液体的挙動や非従来型超伝導など、近藤効果とRuderman-Kittel-Kasuya-Yosida相互作用の競合によって発現する多彩な物性を明らかにしてきた。しかしながら，近藤効果を示す物質の熱膨張は測定されておらず，その振る舞いは未解明のままであった。本研究では、近藤合金La1-xCexCe6の熱膨張測定から、重い電子状態と近藤状態は似た熱膨張を与える可能性を提案した。この結果は、量子臨界点近傍で発現する物性の理解を助けるものであると期待される。