Multidirectionaly thermodynamic study on charge order and charge fluctuation on molecular dimer Mott insulators

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05447
• 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: Osaka University
• Principal Investigator: Yamashita Satoshi 大阪大学, 理学研究科, 助教 (40587466)
• Project Period (FY): 2016-10-21 – 2020-03-31
• Keywords: 電荷秩序 / 分子性導体 / 強相関 / 熱容量測定 / 量子スピン液体

Outline of Final Research Achievements

We have performed heat capacity measurements and thermoelectric power measurements for two solid solution systems in order to clarify the charge order transition behavior and the excitation structure in molecular dimer Mott insulating system, which have phase boundary between quantum spin liquid phase and charge ordered phase. The both results of the heat capacity measurements and the thermoelectric power measurements indicate a higher order transition character in charge ordering of present systems. It is also suggested the non-magnetic transition and forming of charge ordering can be occurred independently. We found a new low-energy excitation structure distinguished from gap-less excitation in spin liquid state. A possibility of short range charge ordering was also suggested.

Free Research Field

固体物性・熱測定

Academic Significance and Societal Importance of the Research Achievements

分子ダイマー型Mott絶縁体系の電荷秩序転移が高次相転移的な性質を持ち、温度低下に従って徐々に電荷秩序が成長するという特徴は、本系においては短距離の電荷秩序形成が可能であることを示している。量子スピン液体領域の電荷秩序相境界近傍において、ギャップレス励起とは別種の低エネルギー励起を観測したこととを合わせて考察すると、量子スピン液体領域においても小規模の電荷秩序形成やその駆動力となる電荷揺らぎの影響が存在することを示唆している。この結果は、電荷揺らぎに焦点をあてることで量子スピン液体相の実現機構を解明できる可能性を示している。