Many remarkable properties of quantum materials emerge from states with intricate coupling between the charge, spin and orbital degrees of freedom. Ultrafast photo-excitations of these materials hold great promise for understanding and controlling the properties of these states. Here we introduce time-resolved resonant inelastic X-ray scattering (trRIXS) as a means of measuring charge, spin and orbital excitations out of equilibrium. These excitations encode the correlations and interactions that determine the detailed properties of the states generated. After outlining the basic principles and instrumentation of tr-RIXS, we review our first observations of transient antiferromagnetic correlations in quasi-two dimensions in a photo-excited Mott insulator and present possible future routes of this fast-developing technique. The increasing number of X-ray free electron laser facilities not only enables tackling long-standing fundamental scientific problems, but also promises to unleash novel inelastic X-ray scattering spectroscopies
Photoinduced two-step insulator-metal transition in Ti4O7 by ultrafast time-resolved optical reflectivity
我们报告的超快时间分辨光学反射率在Ti4 O 7的热载流子动力学的系统调查。我们发现了它的两步绝缘体-金属（I-M）相变的瞬态指示，即在Tc 1处发生从长程序双极化子低温绝缘（LI）相到无序双极化子高温绝缘（HI）相和在Tc 2处到自由载流子金属（M）相的两个相变。结果表明，随着泵浦能量密度的增加，光激发可以有效地降低Tc 1和Tc 2，从而实现I-M跃迁的光控制。我们解决的相图，提供了一个框架的光诱导的I-M转变，并有助于潜在的使用Ti4 O 7的光电和热电器件。
Ultrafast magnetic dynamics in insulating YBa$_2$Cu$_3$O$_{6+x}$ revealed by time resolved two-magnon Raman Scattering
实时测量和控制磁序和相关性是与磁存储器和自旋电子学相关的快速发展的科学领域[1，15]。在这些实验中，超短激光脉冲（泵浦）首先被携带电偶极矩的激发吸收。然后，它们将能量提供给由时间分辨探针监测的磁性子系统。铁磁体的研究已经取得了很大的进展，但反铁磁体的研究更具挑战性。在这里，我们介绍了时间分辨的双磁振子拉曼散射作为一种新的实时探测磁关联，特别适合于反铁磁体。它的应用程序的反铁磁电荷转移绝缘体YBa $_2$ Cu $_3$ O $_{6+x}$显示快速退磁90 fs内的光激发。弛豫回到热平衡的特征在于慢得多的时间尺度。我们解释这些结果的电荷部门的缓慢松弛和快速平衡的磁部门的prethermal状态，其特征在于由参数变化缓慢的电荷部门放松。
Ultrafast collective dynamics of short-range charge/orbital ordering fluctuations in colossal magnetoresistive oxides
巨磁电阻锰氧化物是一种自旋、电荷、轨道和晶格自由度之间存在强耦合的高关联系统，导致复杂的相图和多种有序形式的共存。例如，MnO $_{6} octahedra in CMR manganites and compete with the electron itinerancy favored by double exchange. However, access to the ordered dynamical state has been challenging, mostly due to intrinsic experimental difficulties in measuring fast short-range correlations. Here, we report on a strongly damped low-energy collective mode originating from fast short-range CO fluctuations in La}$ _{0.67}Ca $_{0.33}Mn{O}$ _{3}（LCMO）单晶和薄膜的纳米级电荷/轨道有序（CO）涨落似乎与Jahn-Teller（JT）畸变协同作用。我们阐明了集体模式的色散关系和依赖于平均A位离子半径，r$_{A}，和空穴掺杂浓度。我们的研究结果表明，第一次CMR锰氧化物中的动态…
Orbital-lattice coupling and polaronic dressing of electronic states in Pr$_{0.5}$Ca$_{1.5}$MnO$_4$ revealed by ultrafast broadband spectroscopy
ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology（巴塞罗那科学技术学院光子科学研究所（ICFO））；Aarhus University（奥胡斯大学）；ALBA Synchrotron Light Source（ALBA同步辐射光源）；Univ Rennes（雷恩大学）；CNRS（法国国家科学研究中心）；IMDEA Nanoscience（IMDEA纳米科学研究所）
Identifying and tracking magnetically induced polarization in Fe$_2$Mo$_3$O$_8$ by static and time-resolved second harmonic generation
International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料科学中心）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理国家实验室）；Tsung-Dao Lee Institute, Shanghai JiaoTong University（上海交通大学李政道研究所）
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）
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
Signatures of superconductivity and pseudogap formation in non-equilibrium nodal quasiparticles revealed by ultrafast angle-resolved photoemission
我们用时间分辨和角分辨光电子能谱测量了$_2$ $_2$ O $_2$的各种掺杂的节非平衡电子态。我们发现，这些ungapped状态的初始泵浦诱导的瞬态信号的强烈影响的超导能隙在$T_c$，超导配对波动在$T_p$，和赝能隙在$T^*$的发病。此外，$T_p$标记了通量依赖性瞬态信号中的一个提示性阈值，出现了低于$T_p$的临界通量，该临界通量对应于使所有库珀对断裂所需的能量。这些结果挑战了铜氧化物超导体中结-反结二分法的概念，在结准粒子和铜氧化物相图之间建立了一个新的联系。
