Layer-dependent charge density wave phase transition stiffness in 1T-TaS_(2)nanoflakes evidenced by ultrafast carrier dynamics

作     者：Rui Wang Junbo Zhou Xinsheng Wang Liming Xie Jimin Zhao Xiaohui Qiu Rui Wang;Junbo Zhou;Xinsheng Wang;Liming Xie;Jimin Zhao;Xiaohui Qiu

作者机构：CAS Key Laboratory of Standardization and Measurement for NanotechnologyCAS Center for Excellence in NanoscienceNational Center for.Nanoscience and TechnologyBeijing 100190China Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials LaboratoryDongguan 523808China University of Chinese Acadermy of SciencesBeijing 100049China 

出 版 物：《Nano Research》 (纳米研究（英文版）)

年 卷 期：2021年第14卷第4期

页      面：1162-1166页

核心收录：

学科分类：0808[工学-电气工程] 07[理学] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 080103[工学-流体力学] 070205[理学-凝聚态物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：We thank Prof.Yong Wang(Nankai University)for the valued discussions.We acknowledge financial support from the National Key Research and Development Program of China(Nos.2017YFA0205000,2017YFA0303600,2016YFA0200701) the National Natural Science Foundation of China(Nos.21425310,21790353,21721002,21822502,21673058) Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB36000000,XDB30000000) the Key Research Program of Frontier Sciences of CAS(No.QYZDB-SSW-SYS031). 

主　　题：charge density wave 1T-TaS_(2) layer-dependent phase transition stiffness ultrafast carrier dynamics 

摘      要：Novel physical properties emerge when the thickness of charge density wave(CDW)materials is reduced to the atomic level,owing to the significant modification of the electronic band structure and correlation effects.Here,we investigate the layer-dependent CDW phase transition and evolution of the nonequilibrium state of 1T-TaS_(2)nanoflakes using pump-probe spectroscopy.Both the low-energy single-particle and collective excitation relaxations exhibit sharp changes at〜210 K,indicating a phase transition from commensurate CDW to nearly commensurate CDW state.The single particle process reveals that the phase transition stiffness(PTS)is thickness-dependent.Moreover,a small PTS is observed in thin nanoflakes,which is attributed to the reduced thickness that increases the fluctuation and inhibits the nucleation and growth of discommensurations.In addition,the phase mode vanishes when the discommensuration network appears.Our results suggest that the carrier dynamics could be an efficient operational approach to measuring the quantum phase transition in correlated materials.