Creation of unusual valence compounds and the exploration of novel functions - making use of extreme conditions

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H01195
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Inorganic chemistry
• Research Institution: Osaka University (2018-2019); The University of Tokyo (2017)
• Principal Investigator: Ishiwata Shintaro 大阪大学, 基礎工学研究科, 教授 (00525355)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 高圧合成 / 異常高原子価 / 遷移金属酸化物 / らせん磁性 / 巨大交差相関応答 / ペロブスカイト型酸化物

Outline of Final Research Achievements

We have comprehensively synthesized new perovskite-related compounds containing anomalously high valence 3d transition-metal ions by a high-pressure technique, and discovered a rich variety of unconventional structure and physical properties, reflecting the strong pd hybridization. Notable achievements include the synthesis of novel perovskite PrCuO3 with a quasi-1D structure system and the observation of metal-insulator transition due to an inter-site charge transfer in its derivative, the discovery of novel helimagnetic ordering and giant magnetovolume effect in Sr1-xBaxCoO3 and Sr1-xCaxCoO3, and the discovery of various spin-charge-ordered phases in (Sr,Ba,La)FeO3.

Free Research Field

固体化学、物性物理

Academic Significance and Societal Importance of the Research Achievements

特異な構造と電荷分布を有するPrCuO3およびその置換系(La,Pr)CuO3、強磁性ーらせん磁性転移を示す(Sr,Ba,Ca)CoO3、新奇なトポロジカルらせん磁性を示すSrFeO3とその置換系(Sr,Ba,La)FeO3、というペロブスカイト型構造を有する３種類の新規異常高原子価遷移金属酸化物群の高圧合成と新物性探索を進めたことは、強相関物質科学及び高圧物質科学の基礎学理構築に大きな寄与をもたらしたと言える。また、立方晶ペロブスカイト(Sr,Ba)CoO3における巨大磁気体積効果の発見は、新たな高性能センサ材料や磁気アクチュエータへの応用展開が期待される。