Novel phenomena in the incommensurate orbital/charge ordered state

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04020
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Waseda University
• Principal Investigator: Katsufuji Takuro 早稲田大学, 理工学術院, 教授 (00272386)
• Co-Investigator(Kenkyū-buntansha): 和達 大樹 東京大学, 物性研究所, 准教授 (00579972) ; 森 茂生 大阪府立大学, 工学(系)研究科(研究院), 教授 (20251613) ; 奥田 哲治 鹿児島大学, 理工学域工学系, 准教授 (20347082)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 軌道整列 / 電荷整列 / 非整合 / 緩和現象

Outline of Final Research Achievements

We have investigated the incommensurate superstructures caused by the orbital and charge ordering of d electrons in transition-metal oxides and have studied the exotic physical properties caused by such ordering. We have found characteristic incommensurate superstructures in hollandite Ti oxides with double chains of Ti ions and the V oxides with quasi-triangular lattices of V ions, and have found the anomalies associated with such ordering in transport, magnetic, and thermal properties. From these measurements, we have clarified the physics of incommensurate orbital/charge ordering and have opened up a way in the research of strongly correlated electron systems.

Free Research Field

数物系科学

Academic Significance and Societal Importance of the Research Achievements

物性物理の研究分野の中でも、現在最も活発な研究が進んでいる強相関電子系の研究において、非整合な軌道/電荷秩序という新たな研究分野を作り上げることができた。さらに本研究で扱ったホランダイト型Ti酸化物においては、大きな熱起電力、高い電気伝導度、低い熱伝導度を持つことから、新たなn型熱電材料としても期待されている。