2次元強磁性体の超高速スピンダイナミクスを磁場で制御（Scientists Uncover Magnetic-field Control of Ultrafast Spin Dynamics in 2D Ferromagnets）

2025-06-10 中国科学院(CAS)

Magnetic control acceleration effect of ultrafast demagnetization in 2D magnet FGT. (Image by WANG Zhou)

＜関連情報＞

• https://english.cas.cn/newsroom/research_news/phys/202506/t20250612_1045488.shtml
• https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaf185/8142530?login=false

強磁場中におけるファンデルワールス強磁性体Fe3GeTe2の超高速減磁の加速 Acceleration of ultrafast demagnetization in van der Waals ferromagnet Fe3GeTe2 in high magnetic field

Zhou Wang , Tao Sun , Zhongzhu Jiang , Mengju Yuan , Yuan Huang , Yifan Ren , De Hou , Tao Li , Xinyu Liu , Xuan Luo …
National Science Review  Published:23 May 2025
DOI:https://doi.org/10.1093/nsr/nwaf185

Abstract

The mechanisms of ultrafast laser-induced demagnetization of ferromagnets have been among the most heavily debated topics in ultrafast magnetism from the very beginning of the field. Here, we demonstrate that the time-scale and the efficiency of ultrafast demagnetization of two-dimensional van der Waals ferromagnet Fe₃GeTe₂, excited by femtosecond laser pulse, can be efficiently accelerated by an external magnetic field. With a 1 T magnetic field at T_C = 210 K femtosecond laser excitation causes demagnetization of the ferromagnet by 79% within 22.2 ps, while applying the field 7 T can suppress the demagnetization efficiency down to 52% and accelerate the process so that it is completed within 9.9 ps. We also reveal that the efficiency and the time-scale can be varied in a similar way by changing the temperature of the sample, and the magneto-effect is more pronounced in the middle temperature region (90 to 210 K). Based on these observations we propose a thermodynamic explanation of the findings within the frames of three-temperature model and without involvement of any peculiarities of electronic structure of van der Waals materials. Hence, our work emphasizes that controlling ultrafast demagnetization with the help of an applied magnetic field must be a general phenomenon, which is not limited to van der Waals materials, and thus must be also observed in other magnets.