Study of electronic-ferroelectric domains driven by strong optical and terahertz fields

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01144
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Tohoku University
• Principal Investigator: Itoh Hirotake 東北大学, 理学研究科, 助教 (70565978)
• Co-Investigator(Kenkyū-buntansha): 山本 薫 岡山理科大学, 理学部, 准教授 (90321603)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 電子強誘電体 / 電荷秩序 / テラヘルツ波発生 / テラヘルツ強電場 / 光誘起相転移

Outline of Final Research Achievements

Toward tailoring gigantic optical responses of matters, terahertz (THz) and optical spectroscopies were performed on electronic-ferroelectric (e-FE) domains in strongly-correlated organic conductors. (1) By developing the terahertz-emission microscope, the e-FE domains were found to have a typical size of 100 microns. (2) e-FE domains were found to show characteristic behaviors upon photoexcitation, such as polarization inversion or ultrafast THz oscillation. (3) With the developed intense THz light source, e-FE polarization was found to show ultrafast and gigantic responses following a THz electric field. (4) The newly-developed instrument has enabled precise measurement of pyroelectric current in e-FE materials.

Free Research Field

強相関電子系の光物性

Academic Significance and Societal Importance of the Research Achievements

強相関電子系では強誘電・強磁性・金属・超伝導など多彩な電子状態が競合しており、外部刺激によってこれらを自由に制御できれば基礎応用両面で高価値である。本研究によって、空間的に現れた相競合状態といえるドメイン壁(正負の電子強誘電分極ドメインの境界)が、巨大で高速な光・テラヘルツ応答を示すことが明らかとなった。この成果は、電子状態を光で操るための指針となるだけでなく、ドメイン壁を利用して非バルク的な物性を創り出せる可能性をも示している。