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; Yisheng Chai; Alexey Kimel; Yuping Sun; Zhigao Sheng

doi:10.1093/nsr/nwaf185

Acceleration of ultrafast demagnetization in van der Waals ferromagnet Fe₃GeTe₂ in high magnetic field

Natl Sci Rev. 2025 May 23;12(7):nwaf185. doi: 10.1093/nsr/nwaf185. eCollection 2025 Jul.

Authors

Zhou Wang^{1

2}, Tao Sun^{1

2}, Zhongzhu Jiang³, Mengju Yuan⁴, Yuan Huang⁵, Yifan Ren^{1

2}, De Hou^{1

2}, Tao Li¹, Xinyu Liu¹, Xuan Luo³, Yisheng Chai⁴, Alexey Kimel⁶, Yuping Sun^{1

3

7}, Zhigao Sheng^{1

7}

Affiliations

¹ High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
² University of Science and Technology of China, Hefei 230026, China.
³ Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China.
⁴ Low Temperature Physics Laboratory, College of Physics, Chongqing University, Chongqing 401331, China.
⁵ Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China.
⁶ Institute for Molecules and Materials, Radboud University, Nijmegen 6525 AJ, The Netherlands.
⁷ Collaborative Innovation Center of Advanced Microstructures Nanjing University, Nanjing 210093, China.

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 timescale and the efficiency of ultrafast demagnetization of two-dimensional van der Waals ferromagnet Fe₃GeTe₂, excited by femtosecond laser pulses, can be efficiently accelerated by an external magnetic field. With a 1 T magnetic field at Curie temperature (T _C) = 210 K femtosecond laser excitation causes demagnetization of the ferromagnet by 79% within 22.2 ps, while the application of the field at 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 timescale 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 a three-temperature model and without the involvement of any peculiarities to the 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 also be observed in other magnets.

Keywords: 2D ferromagnets; Fe3GeTe2; demagnetization; magnetic field effect; spin entropy.