Recently, the research group led by Professor Wu Xiaojun from the International Innovation Center of Terahertz Science and Technology of Hangzhou International Innovation Institute, Beihang University, in cooperation with Researcher Meng Sheng, Researcher Zhao Jimin, and Associate Researcher He Wei from the Institute of Physics, Chinese Academy of Sciences, as well as Professor Xiu Faxian’s team from Fudan University, has made great achievement in the generation of ultrafast terahertz spin current at room temperature. Their research results, titled “Above Curie Temperature Ultrafast Terahertz Emission and Spin Current Generation in a Two-Dimensional Superlattice (Fe3GeTe2/CrSb)3,” have been published in National Science Review, a comprehensive scholarly journal with an impact factor of 18.6.
Dr. Li Peiyan at Beihang University, Dr. Wu Na and Dr. Cheng Yu at the Institute of Physics, Chinese Academy of Sciences, and Dr. Liu Shanshan at Fudan University are the co-first authors of the paper. Professor Wu Xiaojun, Researcher Meng Sheng, Researcher Zhao Jimin, Associate Researcher He Weim, and Professor Xiu Faxian are the co-corresponding authors. The Hangzhou International Innovation Institute of Beihang University is the primary affiliation for the study.
The increasing demand for denser information storage and faster data processing has fuelled a keen interest in exploring spin currents up to terahertz (THz) frequencies. The emergent two-dimensional (2D) intrinsic magnetic materials constitute a novel and highly controllable platform to access such femtosecond spin dynamics at atomic layer thickness. However, 2D van der Waals magnets are limited by their Curie temperatures (usually at low temperatures) to exhibit the functioning.
In a 2D superlattice (Fe3GeTe2/CrSb)3, the authors demonstrate ultrafast laser-induced spin current generation and THz radiation at room temperature, overcoming the challenge of its Curie temperature being only 206 K. In tandem with time-resolved magneto-optical Kerr effect measurements and first-principle calculations, they further elucidate the origin of the spin currents—a laser-enhanced proximity effect manifested as a laser-induced reduction of interlayer distance and enhanced electron exchange interactions, which causes transient spin polarization in the heterostructure. The findings present an innovative, magnetic-element-free route for generating ultrafast spin currents in the 2D limit, underscoring the significant potential of laser THz emission spectroscopy in investigating laser-induced extraordinary spin dynamics.
The work was supported by the National Natural Science Foundation of China, the National Key Research and Development Program, the Youth Team in Basic Research Field of Chinese Academy of Sciences, the Open Project of Wuhan National Laboratory for Optoelectronics, etc.
The International Innovation Center of Terahertz Science and Technology of Hangzhou International Innovation Institute at Beihang University, oriented to the major national needs, mainly focuses on the world's scientific frontiers in interdisciplinary research related to terahertz. To address internationally recognized scientific problems and challenges in the terahertz field, the Center conducts research on the radiation theory and technology of high-power and strong-field terahertz light sources, develops terahertz devices with new materials and new structures, and studies terahertz near-field optics, terahertz system integration technologies and their applications.
Professor Wu Xiaojun is a Humboldt Scholar in Germany, a Fellow of the Optical Society of America, a national-level young talent and a Beijing Young Scholar. She has published more than 70 papers in journals such as Nature Photonics, Nature Communications and Advanced Materials as the first or corresponding author, and has been granted more than 20 patents. She has won the first Female Scientist Award of the International Society of Infrared, Millimeter and Terahertz Waves, the Ultrafast Science Global Award, the first prize of the China Science and Technology Youth Forum held by the China Association for Science and Technology, and the Award of Rising Star in Science and Technology. She has given more than 40 plenary or invited reports at important academic conferences in the terahertz field.
Link to the original article: https://doi.org/10.1093/nsr/nwae447
Editor: Lyu Xingyun
