Extremely low-energy collective modes in a quasi-one-dimensional topological system  

作　　者：Zhengxin Wei Shuai Zhang Yulun Su Liang Cheng Haidong Zhou Zhigang Jiang Hongming Weng Jingbo Qi 

机构地区：[1]State Key Laboratory of Electronic Thin Films and Integrated Devices,University of Electronic Science and Technology of China,Chengdu 610054,China [2]Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [3]Department of Physics and Astronomy,University of Tennessee,Knoxville,Tennessee 37996,USA [4]School of Physics,Georgia Institute of Technology,Atlanta,Georgia 30332,USA

出　　处：《Science China(Physics,Mechanics & Astronomy)》2022年第5期90-96,共7页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11974070,11734006,11925408,and 11921004);the Frontier Science Project of Dongguan(Grant No.2019622101004);the National Key R&D Program of China(Grant Nos.2016YFA0300600,and 2018YFA0305700);the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000);the K.C.Wong Education Foundation(Grant No.GJTD-2018-01);the Beijing Natural Science Foundation(Grant No.Z180008);the Beijing Municipal Science and Technology Commission(Grant No.Z191100007219013);the CAS Interdisciplinary Innovation Team。

摘　　要：We have investigated the quasiparticle dynamics and collective excitations in the quasi-one-dimensional material ZrTe_(5) using ultrafast optical pump-probe spectroscopy.Our time-domain results reveal two coherent oscillations having extremely low energies of hω_(1)~0.33 me V(0.08 THz)and hω_(2)-1.9 me V(0.45 THz),which are softened as the temperature approaches two different critical temperatures(~54 K and~135 K).We attribute these two collective excitations to the amplitude mode of photoinduced dynamic charge density waves in ZrTe_(5) with tremendously small nesting wave vectors.Furthermore,a peculiar quasiparticle decay process associated with the hω_(2) mode with a timescale of~1-2 ps is found below the transition temperature T*(~135 K).Our findings provide pivotal information for studying the fluctuating order parameters and their associated quasiparticle dynamics in various low-dimensional topological systems and other materials.

关 键 词：charge density waves ultrafast quasiparticle dynamics amplitude mode 

分 类 号：O469[理学—凝聚态物理]