Using time- and angle-resolved photoemission spectroscopy with selective near- and mid-infrared photon excitations, we investigate the femtosecond dynamics of the charge density wave (CDW) phase in 1$T$-TiSe$_2$, as well as the dynamics of CDW fluctuations at 240 K. In the CDW phase, we observe the coherent oscillation of the CDW amplitude mode. At 240 K, we single out an ultrafast component in the recovery of the CDW correlations, which we explain as the manifestation of electron-hole correlations. Our momentum-resolved study of femtosecond electron dynamics supports a mechanism for the CDW phase resulting from the cooperation between the interband Coulomb interaction, the mechanism of excitonic insulator phase formation, and electron-phonon coupling.
Electron-phonon-dominated charge-density-wave fluctuations in TiSe$_2$ accessed by ultrafast nonequilibrium dynamics
Université de Bordeaux（波尔多大学）；CEA（法国原子能和替代能源委员会）；CELIA（激光与相互作用中心实验室）；Universität Würzburg（维尔茨堡大学）；Institute of Physics, 10000 Zagreb（萨格勒布物理研究所）；European Theoretical Spectroscopy Facility（欧洲理论光谱设施）；Institut National de la Recherche Scientifique（国家科学研究学院）；University of West Bohemia（西波希米亚大学）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）
Ultrafast Stiffening of the Lattice Potential and Metastable State Formation in 1$T$-TiSe$_2$
Central South University（中南大学）；Hunan University of Science and Technology（湖南科技大学）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Uppsala University（乌普萨拉大学）
Revealing Rotational Symmetry Breaking Charge-density Wave Order in Kagome Superconductor (Rb, K)V$_3$Sb$_5$ by Ultrafast Pump-probe Experiments
University of Pennsylvania（宾夕法尼亚大学）；Weizmann Institute of Science（魏茨曼科学研究所）；University of California Santa Barbara（加州大学圣巴巴拉分校）；Oak Ridge National Laboratory（橡树岭国家实验室）
Momentum-Selective Electron and Spin Dynamics under Ultrafast Photoexcitation
CPHT, CNRS, École polytechnique, Institut Polytechnique de Paris（法国高等理工学院）；Institut für Theoretische Physik, Universität Hamburg（汉堡大学理论物理研究所）；European X-Ray Free-Electron Laser Facility（欧洲X射线自由电子激光设施）；The Hamburg Centre for Ultrafast Imaging（汉堡超快成像中心）；Collège de France（法兰西学院）
Ultrafast electron crystallography reveals the atomic pathway of a light-driven correlated insulator-to-metal transition
Stockholm University（斯德哥尔摩大学）；Uppsala University（乌普萨拉大学）；Technion–Israel Institute of Technology（以色列理工学院）；KTH Royal Institute of Technology（瑞典皇家理工学院）；Australian National University（澳大利亚国立大学）
Investigation of Ultrafast Demagnetization and Gilbert Damping and their Correlation in Different Ferromagnetic Thin Films Grown Under Identical Conditions
Thermodynamics of the ultrafast phase transition of vanadium dioxide
IMDEA Nanoscience（IMDEA纳米科学研究所）；CNRS, Univ Rennes, Institut de Physique de Rennes（法国国家科学研究中心，雷恩大学，雷恩物理研究所）；The University of Tokyo（东京大学）；Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST（加泰罗尼亚纳米科学与技术研究所（ICN2），西班牙高等科学研究理事会和巴塞罗那综合理工学院）；Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文系）
Persistent short-range charge correlations revealed by ultrafast melting of electronic order in YBa$_2$Cu$_3$O$_{6+x}$
Linac Coherent Light Source, SLAC National Accelerator Laboratory（直线相干光源，SLAC国家加速器实验室）；Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University（斯坦福材料能源科学研究所，SLAC国家加速器实验室和斯坦福大学）
Excited state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV based time- and angle-resolved photoemission spectroscopy
Nonthermal melting and density wave instability coupled to the lattice in La$_4$Ni$_3$O$_{10}$
Central South University（中南大学）；Fudan University（复旦大学）；Shanghai Research Center for Quantum Sciences（上海量子科学研究中心）；Hefei National Laboratory（合肥国家实验室）；New Cornerstone Science Laboratory（新基石科学研究院）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
