三重简并拓扑半金属磷化钼的时间分辨超快动力学  

Time-resolved ultrafast dynamics in triple degenerate topological semimetal molybdenum phosphide

作　　者：姜聪颖 孙飞 冯子力[1,2] 刘世炳 石友国 赵继民[1,2,4] Jiang Cong-Ying;Sun Fei;Feng Zi-Li;Liu Shi-Bing;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;Strong-Field and Ultrafast Photonics Lab,Institute of Laser Engineering,Beijing University of Technology,Beijing 100124,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]北京工业大学激光工程研究院,强场与超快光子学实验室,北京100124 [4]松山湖材料实验室,东莞523808

出　　处：《物理学报》2020年第7期282-287,共6页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2017YFA0303603,2016YFA0300303,2017YFA0302901);国家自然科学基金(批准号:11574383,11774408,11774399);中国科学院战略性先导科技专项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资助的课题.

摘　　要：拓扑半金属磷化钼(MoP)同时具有三重和二重简并费米子.为了研究其费米面以上的激发态超快动力学特性,对其进行了时间分辨超快泵浦-探测实验.获得了MoP的准粒子动力学,包含来源于电子-声子散射的快分量,寿命为0.3 ps,以及来源于声子-声子散射的慢分量,寿命为150 ps.温度依赖的研究表明,快分量和慢分量的弛豫寿命均随着温度的增加产生微小增大.同时还激发并探测到一支相干态声学支声子,其由热应力引起,频率为0.033 THz且不随温度而改变.对于MoP激发态准粒子超快动力学以及相干态声子的研究为理解该体系总体的激发态超快动力学特性以及电子-声子相互作用对温度的依赖提供了有益的实验依据.We employ the time resolved pump probe experiment to investigate the ultrafast dynamics in a topological semimetal molybdenum phosphide(MoP),which exhibits triple degenerate points in the momentum space.Two relaxation processes with the lifetime of 0.3 and 150 ps have been observed.We attribute the fast component to the electron-phonon scattering and the slow component to the phonon-phonon scattering,respectively.Temperature dependence investigation shows that both the lifetimes of the fast and slow components enhance slightly with increasing temperature.We also successfully generate and detect a thermal-stress-induced coherent acoustic phonon mode with a frequency of 0.033 THz,which does not vary with temperature.Our ultrafast spectroscopy investigation of the quasiparticle dynamics and the coherent phonon in MoP provides useful experimental facts and information about the overall excited state dynamics and the temperature dependence of electron-phonon coupling.

关 键 词：超快光谱 三重简并费米子 电子-声子耦合 拓扑半金属 

分 类 号：O469[理学—凝聚态物理]