五碲化锆超快光激发表面电流特性研究  

Surface current properties of ZrTe5 excited by ultrafast laser

作　　者：吕海慧 李敏 夏宇 刘峥 贺明洋 袁帅[1] 曾和平[1,2,3,4] LUY Hai-Hui;LI Min;XIA Yu;LIU Zheng;HE Ming-Yang;YUAN Shuai;ZENG He-Ping(School of Optical Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093 China;State Key Laboratory of Precision Spectroscopy,East China Normal University,Shanghai 200062 China;Jinan Institute of Quantum Technology,Jinan 250101 China;Chongqing Institute of East China Normal University,Chongqing 401121 China)

机构地区：[1]上海理工大学光电信息与计算机工程学院,上海200093 [2]华东师范大学精密光谱科学与技术国家重点实验室,上海200062 [3]济南量子技术研究院,山东济南250101 [4]华东师范大学重庆研究院,重庆401121

出　　处：《红外与毫米波学报》2022年第4期733-738,共6页Journal of Infrared and Millimeter Waves

基　　金：国家自然科学基金(11727812,61927813)。

摘　　要：利用反射式太赫兹时域光谱研究飞秒光激发狄拉克半金属五碲化锆表面产生的瞬态光电流,进而分析五碲化锆产生太赫兹辐射的几种物理过程。实验结果表明,偏振无关的光电流是表面电流的主要成分,同时太赫兹振幅与泵浦脉冲的线偏振相关,表明部分电流产生于非线性光整流效应。圆偏振光泵浦下,太赫兹振幅随泵浦脉冲呈四倍周期性变化,证实五碲化锆在飞秒脉冲泵浦下产生圆偏振光电流效应。进一步分析超短激光脉冲激发下的太赫兹时域电场,揭示五碲化锆在光诱导下发生反演对称性破缺,产生B声子,形成瞬态外尔点,发生从狄拉克态到外尔态的转变。这对研究拓扑相变和其他拓扑态等方面具有重要意义。The transient photocurrent generated by femtosecond laser excitation on the surface of Dirac semimetal ZrTewere measured through the reflected terahertz time-domain spectroscopy.Experimental results reveal several physical mechanisms of terahertz radiation generated from ZrTe.The results show that the polarization-independent photocurrent is the main component of the surface current,and the terahertz amplitude is related to polarization of the pump laser pulse,which indicates that part of the current is caused by nonlinear optical rectification effect.Under circularly polarized laser pumping,the terahertz amplitude changes four times periodically with the pump laser pulse,which confirms that circular photogalvanic effect of ZrTe.Besides,we have analyzed the terahertz time-domain electric field excited by ultrashort laser pulses.The ZrTeinversion symmetry is broken under the excitation of the femtosecond laser pulse,which produces Bphonons,forming a transient Weyl point,and undergoing a phase transition from the Dirac state to the Weyl state.This is of great significance to the study of topological phase transitions and other topological states.

关 键 词：太赫兹光谱 狄拉克材料 五碲化锆 圆偏光电流效应 

分 类 号：O43[机械工程—光学工程]