相关论文: Ultrafast structural and electronic dynamics of th…
Exciting electrons in solids with intense light pulses offers the possibility of generating new states of matter through nonthermal means and controlling their macroscopic properties on femto- to picosecond timescales. One way to manipulate…
We report the lattice dynamics of transition metal thin films by using the ultrafast electron diffraction. We observe a suppression of the diffraction intensity in a few picosecond after the photoexcitation, which is directly interpreted as…
In the prevalent picture of ultrafast structural phase transitions, the atomic motion occurs in a slowly varying potential energy surface determined adiabatically by the fast electrons. However, this ignores non-conservative forces caused…
Optically-induced phase transitions of the manganite $\rm Pr_{1/3}Ca_{2/3}MnO_3$ have been simulated using a model Hamiltonian, that captures the dynamics of strongly correlated charge, orbital, lattice, and spin degrees of freedom. Its…
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 the quasiparticle populations drove ultrafast…
The ground state properties of correlated electron systems can be extraordinarily sensitive to external stimuli, such as temperature, strain, and electromagnetic fields, offering abundant platforms for functional materials. We present a…
We use ultrafast electron crystallography to study structural changes induced in graphite by a femtosecond laser pulse. At moderate fluences of ~< 21mJ/cm^2, lattice vibrations are observed to thermalize on a time scale of ~8ps. At higher…
In strongly correlated transition metal dichalcogenides, an intricate interplay of polaronic distortions, stacking arrangement, and electronic correlations determines the nature of the insulating state. Here, we study the response of the…
Optical control of magnetism, of interest for high-speed data processing and storage, has only been demonstrated with near-infrared excitation to date. However, in absorbing materials, such high photon energies can lead to significant…
Melting is an everyday phase transition that is determined by thermodynamic parameters like temperature and pressure. In contrast, ultrafast melting is governed by the microscopic response to a rapid energy input and, thus, can reveal the…
Transition metal dichalcogenides with superperiodic lattice distortions have been widely investigated as the platform of ultrafast structural phase manipulations. Here we performed ultrafast electron diffraction on room-temperature…
Transition metal oxides possess complex free energy surfaces with competing degrees of freedom. Photoexcitation allows shaping of such rich energy landscapes. In epitaxially strained $\mathrm{La_{0.67}Ca_{0.33}MnO_3}$, optical excitation…
Utrafast control of material physical properties represents a rapid developing field in condensed matter physics. Yet, accessing to the long-lived photoinduced electronic states is still in its early stage, especially with respect to an…
The ultrafast structure dynamics and surface transient electric field, which are concurrently induced by laser excited electrons of an aluminum nanofilm, have been investigated simultaneously by the same transmission electron diffraction…
We use femtosecond x-ray diffraction to study the structural response of charge and orbitally ordered Pr$_{1-x}$Ca$_x$MnO$_3$ thin films across a phase transition induced by 800 nm laser pulses. By investigating the dynamics of both…
Ultrafast light pulses can modify the electronic properties of quantum materials by perturbing the underlying, intertwined degrees of freedom. In particular, iron-based superconductors exhibit a strong coupling among electronic nematic…
Ultrafast photoexcitation is an emerging route to selective control of phase transitions. However, it is difficult to determine which modes govern the transformation and how effectively they are targeted by photoexcitation. This is…
Bulk layered MX2 transition metal chalcogenides (M = Mo, W and X = S, Se) are known to exhibit an indirect to direct band gap transition as the number of layers is reduced. Previous time-resolved work has principally focused on the…
Metal-insulator transitions (MIT) occurring in non-adiabatic conditions can evolve through high-energy intermediate states that are difficult to observe and control via static methods. By monitoring the out-of-equilibrium structural…
We use an x-ray free-electron laser to study the ultrafast lattice dynamics following above band-gap photoexcitation of the incipient ferroelectric potassium-tantalate, \kto. % We use ultrafast near-UV (central wavelength 266\,nm and 50 fs…