基于超快太赫兹散射型扫描近场光学显微镜的自旋电子太赫兹发射光谱技术(特邀)  

Spintronic Terahertz Emission Spectroscopy Based on Ultrafast Terahertz Scattering Scanning Near-Field Optical Microscope

作　　者：王家琦 代明聪 马一航 王有为 张子建 才家华 陈鹏 万蔡华[3] 韩秀峰[3] 吴晓君 Wang Jiaqi;Dai Mingcong;Ma Yihang;Wang Youwei;Zhang Zijian;Cai Jiahua;Chen Peng;Wan Caihua;Han Xiufeng;Wu Xiaojun(School of Electronic and Information Engineering,Beihang University,Beijing 100191,China;School of Physics,University of Electronic Science and Technology of China,Chengdu 611731,Sichuan,China;Institute of Physics,Chinese Academy of Sciences,Beijing 100191,China;Zhangjiang Laboratory,Shanghai 201210,China)

机构地区：[1]北京航空航天大学电子信息工程学院,北京100191 [2]电子科技大学物理学院,四川成都611731 [3]中国科学院物理研究所,北京100191 [4]张江实验室,上海201210

出　　处：《激光与光电子学进展》2024年第3期248-257,共10页Laser & Optoelectronics Progress

基　　金：国家重点研发计划(2022YFA1604402)。

摘　　要：基于自旋电子材料的太赫兹(THz)发射器具有高效率、超宽带、低成本、易集成等许多独特优势,不仅能够应用在高重复频率激光振荡器驱动的THz时域光谱仪上,而且在高能飞秒激光放大器驱动下能够产生强场THz电磁脉冲,在THz谱学成像、强场THz物理等方面已展现出重要的应用价值。然而,以往基于自旋电子产生THz电磁波的辐射机理和器件研制方面的工作均基于远场THz时域光谱技术,得到的结果是对泵浦激光光斑作用面积的THz发射信息的平均,无法给出材料在微纳尺度上的超快自旋电流以及THz发射性能方面的有用信息。本工作采用光纤飞秒激光器驱动的超快THz散射型扫描近场光学显微成像技术,研究了铁磁异质结材料钨/钴铁硼/铂(W/CoFeB/Pt)在纳米空间尺度下的自旋电子太赫兹发射性能,在横向百纳米尺度上获得了高信噪比的自旋电子THz发射,为纳米空间分辨上实现THz频率的超快自旋电流的产生、探测、操控等提供了新方法,对超快THz自旋光电子学的发展有一定的参考价值。Spintronic terahertz(THz)emitters offer distinct advantages such as high efficiency,ultrabroadband capability,low cost,and easy integration.These emitters find applications not only in THz time-domain spectrometers driven by high-repetition-rate laser oscillators but also in the generation of intense THz electromagnetic pulses powered by highenergy femtosecond laser amplifiers.They have proven valuable in THz spectroscopy imaging and the exploration of strong-field THz physics.However,previous research on spintronic THz radiation mechanisms and device development relies primarily on far-field THz time-domain spectroscopy.The results of this approach present average THz emission information for the laser-pumped spot areas,which does not provide any insights into ultrafast spin currents and THz emission properties for the materials at micro-and nano-scales.In this study,we employ ultrafast THz scattering scanning near-field optical microscopy,driven by a femtosecond fiber laser oscillator,to investigate the spintronic terahertz emission properties of the ferromagnetic heterojunction material W/CoFeB/Pt at nanoscale.The utilization of this technology enables the detection of high signal-to-noise ratio spintronic THz emission at transverse scales as small as hundreds nanometers.This novel approach explores the generation,detection,and manipulation of ultrafast spin currents at THz frequencies with nano-spatial resolution.This study may inspire innovative ideas for the advancement of ultrafast THz spin optoelectronics.

关 键 词：太赫兹辐射 自旋电子 散射型扫描近场光学显微镜 太赫兹自旋电流 

分 类 号：O433.4[机械工程—光学工程]