Control of spin order and observation of its dynamical behavior by using pulsed terahertz electromagnetic wave

2014 Fiscal Year Final Research Report

• Project/Area Number: 23244063
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: The University of Tokyo
• Principal Investigator: SUEMOTO Tohru 東京大学, 物性研究所, 教授 (50134052)
• Co-Investigator(Kenkyū-buntansha): NAKAJIMA Makoto 大阪大学, レーザーエネルギー学研究センター, 准教授 (40361662) ; NISHINO Masamichi 独立行政法人物質・材料研究機構, 理論計算科学ユニット, 主幹研究員 (80391217) ; MINAMI Yasuo 横浜国立大学, 工学(系)研究科(研究院), 研究教員 (60578368)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: テラヘルツ波 / 時間分解 / 磁気共鳴 / スピン再配列転移 / 弱強磁性体 / オルソフェライト / メタマテリアル / 分割リング共振器

Outline of Final Research Achievements

Ultrafast dynamics of spin motion and spin reorientation transition in orthoferrite weak-ferromagnets were investigated by means of several types of pump-and-probe time-resolved spectroscopy based on pulsed magnetic fields accompanying high intensity terahertz (THz) radiation. The main achievements are: (1) Change of spin orientation angle associated with the reorientation transition was successfully observed with THz time-domain spectroscopy. (2) A delay time of ten to several tens of ps was found for the electronic excitation to act on the spin environment. The bottleneck of this process is identified to be the weak interaction between phonons and f-electrons. (3) Spin precession with an exceptionally long coherence time was found. (4) Enhancement of the precession amplitude was observed in a spin system coupled with a split-ring resonator.

Free Research Field

数物系科学