准二维范德瓦耳斯磁性半导体CrSiTe3的THz光谱

Quasi-two-dimensional van der Waals semiconducting magnet CrSiTe3 studied by using THz spectroscopy

准二维范德瓦耳斯磁性材料CrSiTe3同时具有本征磁性与半导体能带结构,在光电子学和纳米自旋电子学领域中具有广泛的应用,近年来吸引了广大科研工作者的兴趣.利用超快太赫兹光谱技术,本文对准二维范德瓦耳斯铁磁半导体CrSiTe3进行了系统的研究,包括太赫兹时域光谱,光抽运-太赫兹探测光谱及太赫兹发射光谱.实验结果表明,样品的太赫兹电导率随温度的变化表现得十分稳定,且样品ab面对太赫兹波的响应呈现为各向同性;800 nm光抽运后的光生载流子表现为一种双指数形式的弛豫变化,复光电导率可以用Drude-Smith模型很好地拟合,光载流子的弛豫过程由电子-空穴对的复合所主导;飞秒脉冲入射到样品表面后可以产生太赫兹辐射,且具有0—2 THz的带宽.本文给出了CrSiTe3在光学及太赫兹波段的光谱,为其在电子及光电子器件方面的设计和优化提供了借鉴与参考.

Quasi-two-dimensional van der Waals ferromagnetic semiconductor CrSiTe3 with wide potential applications in optoelectronics and nanospintronics has aroused the immense interest of researchers due to the coexistence of intrinsic magnetism and semiconductivity.By combining untrafast femtosecond laser and terahertz spectroscopy,including terahertz time-domain spectroscopy,optical pump-terahertz probe spectroscopy and terahertz emission spectroscopy,we carry out systematic investigation into the van der Waals ferromagnetic semiconductor CrSiTe3 crystal.The experimental results indicate that the conductivity of the sample is robust against the temperature change and isotropic terahertz transmission in the ab-plane.Moreover,it is also observed that the photocarriers induced by 800 nm optical pump exhibit a relaxation in the biexponential form and the complex photoconductivity can be well reproduced by the Drude-Smith model.The main relaxation channel of photocarriers is the recombination of electron-hole pairs.With femtosecond pulse illuminating the surface of sample,a strong terahertz radiation signal with a broad band of 0–2 THz is observed.The present study provides the responses of CrSiTe3 to optical and terahertz frequency and offers crucial information for the future design of CrSiTe3-based electronic and optoelectronic devices.