A5059165207- Topological Materials and Phenomena
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Organic and Molecular Conductors Research
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Perovskite Materials and Applications
- Photorefractive and Nonlinear Optics
- Ferroelectric and Piezoelectric Materials
- Microwave Dielectric Ceramics Synthesis
- Iron-based superconductors research
- High-pressure geophysics and materials
- Advanced Condensed Matter Physics
- Graphene research and applications
- Quantum Mechanics and Non-Hermitian Physics
- Quantum and electron transport phenomena
- Advanced Thermoelectric Materials and Devices
- Diamond and Carbon-based Materials Research
- Spectroscopy and Quantum Chemical Studies
- Laser-Matter Interactions and Applications
- Molecular spectroscopy and chirality
- Dielectric materials and actuators
- Quantum chaos and dynamical systems
- Phase-change materials and chalcogenides
Shanghai Jiao Tong University
2019-2025
Chinese Academy of Sciences
2025
Institute of Physics
2025
Tianjin University
2017-2018
Institute of Applied Physics and Computational Mathematics
2004
In magnetic topological insulators (TIs), the interplay between order and nontrivial topology can induce fascinating quantum phenomena, such as anomalous Hall effect, chiral Majorana fermions axion electrodynamics. Recently, a great deal of attention has been focused on intrinsic TIs, where disorder effects be eliminated to large extent, which is expected facilitate emergence phenomena. despite intensive efforts, experimental evidence surface states (SSs) remains elusive. Here, by combining...
The interplay between different degrees of freedom governs the emergence correlated electronic states in quantum materials, with charge density waves (CDW) often coexisting other exotic phases. Under thermal equilibrium, traditional CDW are consequentially accompanied by structural phase transitions. In contrast, ultrafast photoexcitation allows access to where a single degree dominates time domain, enabling study underlying physics without interference. Here, we report realization...
Abstract In low-dimensional systems with strong electronic correlations, the application of an ultrashort laser pulse often yields novel phases that are otherwise inaccessible. The central challenge in understanding such phenomena is to determine how dimensionality and many-body correlations together govern pathway a non-adiabatic transition. To this end, we examine layered compound, 1 T -TiSe 2 , whose three-dimensional charge-density-wave (3D CDW) state also features exciton condensation...
We reveal an ultrafast purely electronic phase transition in \TNS, which is a plausible excitonic insulator, after excited by infrared laser pulse. Specifically, the order parameter of strong electron-hole binding shrinks with enhancing pump pulse, and above critical fluence, photo-excited semimetallic state experimentally identified absence structural transition. In addition, bare valence conduction bands also effective exciton energy \TNS~are determined. These findings detailed analysis...
The ultrafast electronic structures of the charge density wave material 1T-TiSe_{2} were investigated by high-resolution time- and angle-resolved photoemission spectroscopy. We found that quasiparticle populations drove phase transitions in within 100 fs after photoexcitation, a metastable metallic state, which was significantly different from equilibrium normal phase, evidenced far below transition temperature. Detailed pump-fluence-dependent experiments revealed photoinduced state result...
We present the development of a time- and angle-resolved photoemission spectroscopy based on Yb-based femtosecond laser hemispherical electron analyzer. The energy pump photon is tunable between 1.4 1.9 eV, pulse duration around 30 fs. use KBe2BO3F2 nonlinear optical crystal to generate probe pulses, which up 6.7 obtain an overall time resolution 1 ps 18 meV. In addition, β-BaB2O4 crystals are used alternative pulses at 6.05 giving 130 fs 19 illustrate performance system with representative...
Abstract Upon femtosecond laser excitation in quantum materials, it is possible to study the many-body interactions through non-equilibrium processes, realize ultrafast electronic phase transitions, and achieve photoinduced novel states or hidden states. Such studies of interaction between materials are frontiers attract significant research interests field condensed matter physics. Time- angle-resolved photoemission spectroscopy a key experimental tool dynamics after photoexcitation. This...
High-resolution time- and angle-resolved photoemission measurements were made on FeSe superconductors. With ultrafast photoexcitation, two critical excitation fluences that correspond to electronic phase transitions found only in the $d_{yz}$-orbit-derived band near Brillouin-zone center within our time energy resolution. Upon comparison detailed temperature dependent measurements, we conclude there are equilibrium (at approximately 90 120 K) above superconducting transition temperature, an...
Using high-resolution angle-resolved and time-resolved photoemission spectroscopy, we have studied the low-energy band structures in occupied unoccupied states of three ternary compounds GeBi 2 Te 4 , SnBi Sn 0.571 Bi 2.286 Se near Fermi level. In previously confirmed topological insulator compounds, existence Dirac surface state found that bulk energy gap is much larger than first-principles calculations. was observed, consistent with calculations, indicating it a insulator. The...
We reveal the electronic structure in YbCd 2 Sb , a thermoelectric material, by angle-resolved photoemission spectroscopy (ARPES) and time-resolved ARPES (trARPES). Specifically, three bulk bands at vicinity of Fermi level are evidenced near Brillouin zone center, consistent with density functional theory (DFT) calculation. It is interesting that spin-unpolarized respond unexpectedly to right- left-handed circularly polarized probe. In addition, hole band surface states, which not sensitive...
High-resolution angle-resolved photoemission measurements were taken on FeSe$_{1-x}$S$_x$ (x=0, 0.04, and 0.08) superconductors. With an ultrahigh energy resolution of 0.4 meV, unusual two hole bands near the Brillouin-zone center, which was possibly a result additional symmetry breaking, identified in all sulfur-substituted samples. In addition, both highly anisotropic superconducting gaps with limited nodes evidenced. We find that larger gap outer band is reduced linearly to nematic...
We present the development of a high-precision sample-position-autocorrection system for photoemission experiments. A binocular vision method based on image pattern matching calculations was realized to track sample position with an accuracy better than 1 µm, which much smaller spot size incident laser. illustrate performance representative data topological insulator Bi2Se3 and optimally doped cuprate superconductor Bi2Sr2CaCu2O8+δ. Our provides new possibilities studying...
High-resolution time- and angle-resolved photoemission measurements were conducted on the topological insulator ZrTe5. With strong femtosecond photoexcitation, a possible ultrafast phase transition from weak to insulating was experimentally realized by recovering energy gap inversion in time scale that shorter than 0.15 ps. This photoinduced transient can last longer 2 ps at highest excitation fluence studied, it cannot be attributed heating of electrons or modification conduction band...
通过飞秒激光激发固体材料，可利用材料中不同自由度的响应时间尺度研究多体相互作用、追踪超快相变过程、实现光诱导新物态或隐藏态等，是凝聚态物理研究的前沿和重要探索方向。时间分辨角分辨光电子能谱是近十多年发展起来的研究量子材料在飞秒激光激发后超快电子结构动力学的关键实验手段。本文回顾了基于非线性光学晶体和高阶倍频的时间分辨角分辨光电子能谱的基本原理和组成，以及利用其对量子材料的超快电子结构动力学进行的研究。主要包括四个方面的研究进展：（1）量子材料的非占据电子态探测；（2）光诱导的超快电子结构相变；（3）关联电子材料中电声相互作用强度确定；（4）光致新物态。最后，讨论了时间分辨角分辨光电子能谱未来可能的发展方向。
1 T -TiSe2 hosts a 3D charge-density-wave (CDW) state that also features exciton condensation. We find photoexcitation suppresses the CDW while creating 2D CDW, process controlled by excitonic correlations in system.