NMR study on the internal structure of a quantum spin liquid state in the triangular lattice antiferromagnets

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340082
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Kyoto University
• Principal Investigator: MAEGAWA Satoru 京都大学, 人間・環境学研究科(研究院), 名誉教授 (40135489)
• Co-Investigator(Kenkyū-buntansha): ITOU Tetsuaki 東京理科大学, 理学部, 准教授 (50402748) ; OYAMADA Akira 京都大学, 大学院人間・環境学研究科, 助教 (60211835)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: スピン液体 / 三角格子 / 反強磁性体 / 核磁気共鳴 / フラストレーション / 量子スピン

Outline of Final Research Achievements

We have performed NMR measurements on the organic triangular-lattice spin liquid system EtMe3Sb[Pd(dmit)2]2. The measurements were conducted on a single crystal at ultra-low temperatures and under applied pressures. We found that a slowly fluctuating electronic state is realized around the Mott boundary, which is situated around 5 kbar. This indicates that the charge degree of freedom and the randomness, which has been overlooked previously, play a vital role to realize the spin liquid state in EtMe3Sb[Pd(dmit)2]2.
We also discovered new rare-earth quantum-spin antiferromagnets on the triangular lattice, CeZn3P3 and YbCuGe. Our NMR measurements clarified that the magnetic diagram in CeZn3P3 is affected by the quantum spin fluctuation, and that in YbCuGe extremely slow spin fluctuation remains even below the ordering temperature. These results demonstrate that the quantum spin fluctuations are still important in the magnetically ordered state of the frustrated magnets.

Free Research Field

低温磁性物理学