Study of pressure induced valence transition and orbital effect on Ce compounds under high field

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05146
• 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: Shimane University
• Principal Investigator: Fujiwara Kenji 島根大学, 総合理工学研究科, 教授 (50238630)
• Project Period (FY): 2015-10-21 – 2018-03-31
• Keywords: 超伝導 / 重い電子系 / 圧力効果 / 強磁場 / 核磁気共鳴

Outline of Final Research Achievements

Cu-NMR of heavy fermion superconductor CeCu2Si2 was performed under high pressure (5.4, 6.2 and 7.0 GPa) and high field (5～22 T). Ce valence and spin state were investigated by electric field gradient (EFG) at Cu sites, and by Knight Shift (K) and nuclear spin lattice relaxation time (T1), respectively. Above 5 GPa, EFG, K and 1/T1 decrease below identical temperature (T*). These behavior suggest that new crossover with valence change occurs below T*. T* monotonically increases with applying pressure (ex. T*=20, 40, 55K at 5.4, 6.2 and 7.0 GPa). Furthermore, T* is independent of magnetic field between 7 and 22 T. Therefore, the crossover at T* field induced valence transition does not result from field induced valence transition predicted by valence fluctuation model.

Free Research Field

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