飞秒激光泵浦LaAlO_(3)/SrTiO_(3)异质结产生太赫兹波辐射  

Terahertz emission from LaAlO_(3)/SrTiO_(3) heterostructures pumped with femtosecond laser

作　　者：魏高帅 张慧[3] 吴晓君 张洪瑞 王春 王博 汪力[1] 孙继荣[1] Wei Gao-Shuai;Zhang Hui;Wu Xiao-Jun;Zhang Hong-Rui;Wang Chun;Wang Bo;Wang Li;Sun Ji-Rong(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;School of Integrated Circuit Science and Engineering,Beihang University,Beijing 100191,China;School of Electronic and Information Engineering,Beihang University,Beijing 100191,China)

机构地区：[1]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190 [2]中国科学院大学物理科学学院,北京100049 [3]北京航空航天大学集成电路科学与工程学院,北京100191 [4]北京航空航天大学电子信息工程学院,北京100191

出　　处：《物理学报》2022年第9期47-53,共7页Acta Physica Sinica

基　　金：北京市自然科学基金(批准号:4194083);国家自然科学基金(批准号:61905007,11827807,61775233);国家重点研发计划(批准号:2019YFB2203102)资助的课题。

摘　　要：自铁磁金属在飞秒激光泵浦下的超快退磁效应发现以来,电子的自旋属性逐渐被应用于太赫兹电磁波的产生.利用逆Rashba-Edelstein效应产生太赫兹辐射首先在Ag/Bi界面得到证实,而LaAlO_(3)/SrTiO_(3)界面通过该效应产生直流的自旋-电荷转换效率要高于Ag/Bi界面约一个数量级,但利用该结构转化自旋流来产生太赫兹的有效性尚待系统的研究.本文制备了NiFe/LaAlO_(3)//SrTiO_(3)(001)系列样品,在飞秒激光泵浦下观察到了太赫兹辐射的产生及其对磁场方向的依赖效应,并通过改变LaAlO;层的厚度验证了超扩散模型与光学传输模型的有效性,观察到了在LaAlO_(3)/SrTiO_(3)界面由于多次反射导致太赫兹波的减弱,为进一步优化太赫兹波的产生提供了实验和理论支持.Since the discovery of the ultrafast demagnetization of the ferromagnetic metal,the spin degree of electrons is gradually used to generate terahertz radiation.The terahertz radiation generated by the inverse RashbaEdelstein effect was confirmed first at the interface of Ag/Bi.However,the spin-to-charge conversion efficiency of the LaAlO_(3)/SrTiO_(3) interface is one order of magnitude lager than that of the Ag/Bi interface under equilibrium or quasi-equilibrium condition.Whether the LaAlO_(3)/SrTiO_(3) heterostructures can be used to convert spin current to generate terahertz radiation remains to be systemically studied.In this work,we fabricate the NiFe/LaAlO_(3)//SrTiO_(3) heterostructures and investigate the generation of terahertz radiation by femtosecond laser pumping and its dependence of the magnetic field direction.We change the thickness of the LaAlO;to show the applicability of the super diffusive spin transport model and optical transmission model.We find the multireflections at the LaAlO_(3)/SrTiO_(3) interface weaken the terahertz radiation intensity.This work provides experimental and theoretical support for further optimizing the generation of terahertz electromagnetic waves.

关 键 词：太赫兹辐射 自旋流 逆Rashba-Edelstein效应 氧化物异质结 

分 类 号：O469[理学—凝聚态物理]