NMR studies of novel quantum states in spni-orbit coupled Re oxides

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03829
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: High Energy Accelerator Research Organization (2021-2022); The University of Tokyo (2020)
• Principal Investigator: Takigawa Masashi 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 協力研究員 (10179575)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 核磁気共鳴 / スピン軌道強結合系 / レニウム酸化物 / 多極子秩序

Outline of Final Research Achievements

NMR experiments have been performed on single crystals of the spin-orbit-coupled-metal Cd2Re2O7 and the double-perovskite Mott insulator Ba2MgReO6 in order to explore novel ordered states generated by 5d electron systems with strong spin-orbit interaction. For Cd2Re2O7, Knight shift measurements of 111Cd nuclei revealed Eu symmetry of the order parameter realized by the inversion-breaking phase transition with the help of a novel analysis method to identify the irreducible representation of the point group of the nuclei, to which the shift tensor in the ordered phases belong. For Ba2MgReO6, we determined the magnetic dipole and octupole moments from the anisotropic hyperfine fields at the oxygen nuclei in the tilted antiferromagnetic phase.

Free Research Field

物性物理学実験

Academic Significance and Societal Importance of the Research Achievements

本研究は強相関電子系の多彩な秩序状態、特に磁気双極子にとどまらない高次多極子のいわゆる隠れた秩序状態の検出に、NMRが有効であることを示した。その中で、ナイトシフトなどNMR応答を支配するテンソル量を、サイトの点群対称性の既約表現の基底によって分類するという新しい解析方法を提示した。また磁気八極子など高次多極子を定量的に評価する方法を提示した。