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
Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular intere...Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular interest to investigate photon-induced emerging phenomena in spatially confined strongly correlated systems,which are important for applications of these materials in future electronic devices.Colossal magnetoresistive manganites materials offer an ideal platform for such study due to their sensitivity to photo-excitation.Here,we fabricated 900 nm wide La_(0.325)Pr_(0.3)Ca_(0.375)Mn O_3strips,whose width is comparable to the size of the electronic phase separation(EPS)domains in this system.We observed the photoinduced critical fluctuations in the strips,where abrupt resistivity jumps occurred upon photoinduced phase transition depending sensitively on the light intensity.Based on the microscopic views of the EPS domains under photoexcitation,we conclude that such photo-induced resistivity fluctuations originate from the photoinduced phase fluctuations of individual EPS domains when their size becomes comparable to the strip width.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.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0300702)the National Basic Research Program of China(973 Program)(Grant No.2014CB921104)+1 种基金the Program of Shanghai Academic Research Leader(Grant No.17XD1400400)the National Natural Science Foundation of China(Grant No.11504053)
文摘Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular interest to investigate photon-induced emerging phenomena in spatially confined strongly correlated systems,which are important for applications of these materials in future electronic devices.Colossal magnetoresistive manganites materials offer an ideal platform for such study due to their sensitivity to photo-excitation.Here,we fabricated 900 nm wide La_(0.325)Pr_(0.3)Ca_(0.375)Mn O_3strips,whose width is comparable to the size of the electronic phase separation(EPS)domains in this system.We observed the photoinduced critical fluctuations in the strips,where abrupt resistivity jumps occurred upon photoinduced phase transition depending sensitively on the light intensity.Based on the microscopic views of the EPS domains under photoexcitation,we conclude that such photo-induced resistivity fluctuations originate from the photoinduced phase fluctuations of individual EPS domains when their size becomes comparable to the strip width.
