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Optical pump-terahertz emission probe of ultrafast magnetization dynamics
Chen Huang1, Zhangshun Li1, Bo Lu1
1Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
The Journal of Chemical Physics
|December 9, 2025
Summary
We developed a new optical pump-terahertz (THz) emission spectroscopy to study ultrafast spin dynamics. This method reveals magnetization quenching and recovery in materials under ambient conditions.
Area of Science:
- Condensed matter physics
- Materials science
- Ultrafast spectroscopy
Background:
- Ultrafast spin dynamics are crucial for fundamental understanding and spintronic device development.
- Current methods face challenges in probing spin dynamics under realistic operating conditions.
Purpose of the Study:
- To introduce a novel spectroscopic method, optical pump-terahertz (THz) emission (OPTE), for studying ultrafast spin dynamics.
- To demonstrate OPTE's capability for contact-free, ambient condition measurements.
- To analyze magnetization dynamics in a laser-excited Fe monolayer.
Main Methods:
- Utilizing optical pump-terahertz (THz) emission (OPTE) spectroscopy.
- Employing a contact-free measurement approach under ambient conditions.
- Analyzing distinct magnetization quenching and recovery components.
Main Results:
- Direct access to ultrafast demagnetization and re-magnetization dynamics was achieved.
- Magnetization quenching occurred in less than 0.5 picoseconds.
- Distinct fast and slow magnetization recovery components were identified, linked to spin-lattice coupling and heat diffusion.
Conclusions:
- The OPTE method provides a powerful platform for probing ultrafast spin dynamics.
- This technique is suitable for studying materials under realistic device-operation conditions.
- OPTE can be used to optimize magneto-optical recording materials and THz emission applications.
