Study of high-pressure quantum phase of orthogonal dimer spin system by low-temperature 4 GPa class high-pressure ESR measurement

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03746
• 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: Kobe University
• Principal Investigator: Sakurai Takahiro 神戸大学, 研究基盤センター, 助教 (60379477)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 熱検出型ESR / 高圧 / 直交ダイマー / 直接遷移 / 電場励起

Outline of Final Research Achievements

We have developed a pressure cell for ESR measurement, which can generate a pressure above 3 GPa. We also have succeeded in observing ESR under pressure with thermal detection technique, which observes ESR by the temperature increase of the sample due to the spin relaxation. Taking advantage of the fact that this technique can make the probe compact, we combined it with a split-pair type superconducting magnet. This enables us to obtain the magnetic field angle dependence of ESR spectra under pressure. This is very useful for detailed observation of the high-pressure quantum phase of the orthogonal dimer system SrCu2(BO3)2. Polarization dependence measurements of the direct transition ESR mode were carried out for this material using a wire grid. As a result, it was found that the direct transition mode in this system can be excited not only by the magnetic field component of electromagnetic waves but also by the electric field component.

Free Research Field

電子スピン共鳴

Academic Significance and Societal Importance of the Research Achievements

本研究の意義は、強磁場、高周波数下で、3 GPaという高圧下においてESR測定が可能な、更にその磁場角度依存性測定をも可能なシステムを構築した点にある。これは高圧量子相の解明が望まれるSrCu2(BO3)2においても威力を発揮すると期待される。しかも観測に用いた熱検出法は、専用のミリ波検出器が不要、周波数の制限がない等、汎用性、拡張性が高い。また同物質については、従来Dzyaloshinsky-Moriya由来の振動磁場励起によるとされてきた本系のESRの直接遷移モードが、振動電場によっても励起可能であることを示した。これは今後の理論研究等にバラエティを与えるものである。