Narrow band terahertz wave emitter using ferromagnetic ultrathin films

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14218
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: SASAKI Yuta 国立研究開発法人物質・材料研究機構, 若手国際研究センター, NIMSポスドク研究員 (60855782)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: テラヘルツ / スピントロニクス / 金属薄膜 / 全光学的時間分解分光 / 超短パルスレーザー

Outline of Final Research Achievements

Terahertz waves are a collective term for electromagnetic waves with frequencies ranging from 0.1 to 10 THz. They are being explored as a valuable tool for the analysis of explosives, drugs, and other substances. Conventionally, terahertz waves have been generated using semiconductor materials. However, recently there has been a growing interest in efficient terahertz wave generation from ultrathin films of ferromagnetic metals. In this study, we aimed to develop materials for efficient and narrowband terahertz wave emission, which is crucial for practical applications.
We found that the material called Co2MnSi exhibits remarkably high efficiency in injecting spin angular momentum, making it a promising candidate for terahertz wave emission devices. Additionally, we discovered that MnCrAlGe films can efficiently excite spin dynamics in the terahertz wave range.

Free Research Field

強磁性金属薄膜

Academic Significance and Societal Importance of the Research Achievements

テラヘルツ波帯の物性評価では, 一般的な電気測定機器の周波数帯域を超えているため計測が困難であり, 特に強磁性材料におけるテラヘルツ波帯のスピンダイナミクスはあまり調べられてこなかった. 本研究では, そのような技術的困難を全光学的手法を用いて克服し, 様々な材料についてテラヘルツ波帯のダイナミクスを明らかにした点で学術的意義がある. また, 高効率なテラヘルツ波光源やMnCrAlGeおよびFePtといった磁性材料において実際にテラヘルツ波帯の磁化ダイナミクスを実証することで, 今後強磁性金属極薄膜を用いたテラヘルツ素子の開発につながる点で社会的意義がある.