三重简并拓扑半金属MoP中超快圆偏振光产生和调控光生热电流  

Generation and control of photo-excited thermal currents in triple degenerate topological semimetal MoP with circularly polarized ultrafast light pulses

作　　者：加孜拉·哈赛恩 朱恪嘉 孙飞 吴艳玲 石友国[1,3] 赵继民 Jiazila Hasaien;Zhu Ke-Jia;Sun Fei;Wu Yan-Ling;Shi You-Guo;Zhao Ji-Min(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;Songshan Lake Materials Laboratory,Dongguan 523808,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]松山湖材料实验室,东莞523808

出　　处：《物理学报》2020年第20期112-118,共7页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2017YFA0303603,2016YFA0300303,2017YFA0302901);国家自然科学基金(批准号:11574383,11774408,11774399);中国科学院战略重点研究计划先导专项B(批准号:XDB30000000);中国科学院国际合作项目(批准号:GJHZ1826);北京市自然科学基金(批准号:4191003);中国科学院创新交叉团队项目资助的课题.

摘　　要：超快激光可以用来产生和调控拓扑量子材料中的拓扑相变和自旋极化电流,这些光诱导产生的新奇物性源于材料中受到体系对称性保护的线性色散能带结构的简并节点.作为一种同时具有两重和三重简并节点的拓扑半金属,磷化钼(MoP)是一类非常独特的拓扑半金属体系.本文初步探索了三重简并拓扑半金属晶体MoP中产生自旋极化电流和奇异光学响应的机理,设计并搭建了以圆偏振光产生并调控光电流的实验装置.首先采用该装置成功在拓扑绝缘体Bi2Se3中产生了光电流,与国际上已报道的实验结果对比效果很好,证明了实验装置的可行性和可靠性;进而对MoP进行了同样的光电流产生与调控实验.采用400 nm的圆偏振超快激光脉冲,在样品不同位置成功观测到了电流信号,分析认为其为热电流,不是与三重简并拓扑特性相关的光电流.这为未来进一步产生和调控光电流提供了重要的研究基础,对于研究普遍的拓扑量子材料的光电流效应具有可借鉴的意义.Ultrafast spectroscopy is a powerful method to generate and control topological phase transitions and spinpolarized electrical currents in topological quantum materials.These light-induced novel physical properties originate from the topologically nontrivial states of Dirac and Weyl fermions.The topological semimetal molybdenum phosphide(MoP)exhibits double and triple degenerate points in the momentum space.We present the preliminary results of spin-polarized electrical currents and optical response investigations of MoP.We design and construct an experimental setup to perform the photocurrent generation and control by circularly polarized light in topological insulator Bi2Se3.The results compare well with those reported,which confirms the validity and reliability of our experimental setup.Further,we conduct the photocurrent experiment on MoP by using 400 nm laser pulses for excitation and successfully detect the current signals at different sample positions.We attribute the observed currents to photo-induced thermal currents(not the photo current associated with the triple degenerate topological properties),which facilitates generating and controlling photocurrents in MoP in the future investigation.Our thermal current investigations are of essence for further exploring the photocurrents in various types of topological quantum materials.

关 键 词：光电流 三重简并拓扑材料 超快光谱 自旋极化 

分 类 号：O469[理学—凝聚态物理]