Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interact...Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.展开更多
Layered deintercalamble alkall metal oxides,such as LixCoO2,have been a subject of intense research activities in the past years owing to the technological applications as the battery electrodes and thermoelectric... Layered deintercalamble alkall metal oxides,such as LixCoO2,have been a subject of intense research activities in the past years owing to the technological applications as the battery electrodes and thermoelectric materials[1-2].Vacancy and cation ordering is a notable structural feature in this system.Extensive theoretical and experimental study has been performed concerning this issue in several typical materials[1-2].……展开更多
超快透射电子显微镜(Ultrafast Transmission Electron Microscopy,UTEM)集成了高空间和时间分辨率,使直接可视化材料的动力学过程成为可能。本文主要介绍UTEM系统的发展和应用:基于泵浦-探测(Pump-Probe)技术的UTEM系统的基本原理;目...超快透射电子显微镜(Ultrafast Transmission Electron Microscopy,UTEM)集成了高空间和时间分辨率,使直接可视化材料的动力学过程成为可能。本文主要介绍UTEM系统的发展和应用:基于泵浦-探测(Pump-Probe)技术的UTEM系统的基本原理;目前全世界范围内几个主要机构的UTEM系统;中科院物理所李建奇研究员团队自主研发的基于热发射电子枪的第一代UTEM系统和基于场发射电子枪(Field Emission Electron Gun,FEG)的第二代UTEM系统;UTEM系统中的超快实空间成像、超快电子衍射(Ultrafast Electron Diffraction,UED)、时间分辨电子能量损失谱(Time Resolved Electron Energy Loss Spectrum,TREELS)相结合的最新研究成果,例如晶格和电子动力学、相变动力学、光诱导近场电子显微镜(Photon-Induced-Near-Field Electron Microscopy,PINEM)等。目前,超快电镜已经成为研究微纳尺度下非平衡态动力学过程的独一无二的工具。未来,随着电子脉冲质量和TEM的空间分辨率不断提高,有望实现具有更高时空分辨能力的UTEM系统。中国对UTEM的研究投入较少,当前应抓住UTEM的发展机遇,高效推进UTEM领域的关键技术、核心部件和重大产品创新和产业发展,将科技创新和产业发展紧密衔接。展开更多
Single crystals of CeMn_(0.85)Sb_(2) have been successfully synthesized by using the Bi as flux.Analysis of single crystal x-ray diffraction data confirms that CeMn_(0.85)Sb_(2) crystallizes in the HfCuSi_(2)-type str...Single crystals of CeMn_(0.85)Sb_(2) have been successfully synthesized by using the Bi as flux.Analysis of single crystal x-ray diffraction data confirms that CeMn_(0.85)Sb_(2) crystallizes in the HfCuSi_(2)-type structure with the space group P4/nmm(No.129).In the case of H‖c,CeMn_(0.85)Sb_(2) displays a robust antiferromagnetic transition at~160 K for Mn-sublattice,and there is no sign of magnetic order regarding Ce-sublattice.In the case of the Mn-sublattice shows signs of magnetic order at 160 K and 116 K,indicating a possible spin reorientation.There is no sign of magnetic order for the Cesublattice either,but,alternating current magnetic susceptibility measurements reveal a spin glass state below 18 K in the case of H⊥c.Isothermal magnetization curves measured below magnetic order with H⊥c show saturation and even large hysteresis at 2 K,indicating the presence of a ferromagnetic component.In addition,a field-induced spin-flop transition is observed in the case of H⊥c,indicating a field-induced spin reorientation of Mn spins.Electrical resistivity measurements indicate a metallic nature for CeMn_(0.85)Sb_(2) and large anisotropy which is consistent with its quasi-two-dimensional layered structure.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.U22A6005 and 12074408)the National Key Research and Development Program of China (Grant No.2021YFA1301502)+7 种基金Guangdong Major Scientific Research Project (Grant No.2018KZDXM061)Youth Innovation Promotion Association of CAS (Grant No.2021009)Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant Nos.YJKYYQ20200055,ZDKYYQ2017000,and 22017BA10)Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant Nos.XDB25000000 and XDB33010100)Beijing Municipal Science and Technology Major Project (Grant No.Z201100001820006)IOP Hundred Talents Program (Grant No.Y9K5051)Postdoctoral Support Program of China (Grant No.2020M670501)the Synergetic Extreme Condition User Facility (SECUF)。
文摘Ultrafast transmission electron microscope(UTEM) with the multimodality of time-resolved diffraction, imaging,and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump–probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photoinduced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light–free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams.
文摘 Layered deintercalamble alkall metal oxides,such as LixCoO2,have been a subject of intense research activities in the past years owing to the technological applications as the battery electrodes and thermoelectric materials[1-2].Vacancy and cation ordering is a notable structural feature in this system.Extensive theoretical and experimental study has been performed concerning this issue in several typical materials[1-2].……
文摘超快透射电子显微镜(Ultrafast Transmission Electron Microscopy,UTEM)集成了高空间和时间分辨率,使直接可视化材料的动力学过程成为可能。本文主要介绍UTEM系统的发展和应用:基于泵浦-探测(Pump-Probe)技术的UTEM系统的基本原理;目前全世界范围内几个主要机构的UTEM系统;中科院物理所李建奇研究员团队自主研发的基于热发射电子枪的第一代UTEM系统和基于场发射电子枪(Field Emission Electron Gun,FEG)的第二代UTEM系统;UTEM系统中的超快实空间成像、超快电子衍射(Ultrafast Electron Diffraction,UED)、时间分辨电子能量损失谱(Time Resolved Electron Energy Loss Spectrum,TREELS)相结合的最新研究成果,例如晶格和电子动力学、相变动力学、光诱导近场电子显微镜(Photon-Induced-Near-Field Electron Microscopy,PINEM)等。目前,超快电镜已经成为研究微纳尺度下非平衡态动力学过程的独一无二的工具。未来,随着电子脉冲质量和TEM的空间分辨率不断提高,有望实现具有更高时空分辨能力的UTEM系统。中国对UTEM的研究投入较少,当前应抓住UTEM的发展机遇,高效推进UTEM领域的关键技术、核心部件和重大产品创新和产业发展,将科技创新和产业发展紧密衔接。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U22A6005,U2032204,and 12104492)the Guangdong Major Scientific Research Project(Grant No.2018KZDXM061)+3 种基金the National Key Research and Development Program of China(Grant No.2021YFA1400401)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33010000)the K.C.Wong Education Foundation(Grant No.GJTD-2018-01)the Informatization Plan of Chinese Academy of Sciences(Grant No.CAS-WX2021SF0102)。
文摘Single crystals of CeMn_(0.85)Sb_(2) have been successfully synthesized by using the Bi as flux.Analysis of single crystal x-ray diffraction data confirms that CeMn_(0.85)Sb_(2) crystallizes in the HfCuSi_(2)-type structure with the space group P4/nmm(No.129).In the case of H‖c,CeMn_(0.85)Sb_(2) displays a robust antiferromagnetic transition at~160 K for Mn-sublattice,and there is no sign of magnetic order regarding Ce-sublattice.In the case of the Mn-sublattice shows signs of magnetic order at 160 K and 116 K,indicating a possible spin reorientation.There is no sign of magnetic order for the Cesublattice either,but,alternating current magnetic susceptibility measurements reveal a spin glass state below 18 K in the case of H⊥c.Isothermal magnetization curves measured below magnetic order with H⊥c show saturation and even large hysteresis at 2 K,indicating the presence of a ferromagnetic component.In addition,a field-induced spin-flop transition is observed in the case of H⊥c,indicating a field-induced spin reorientation of Mn spins.Electrical resistivity measurements indicate a metallic nature for CeMn_(0.85)Sb_(2) and large anisotropy which is consistent with its quasi-two-dimensional layered structure.
