Toward nonthermal control of excited quantum materials: framework and investigations by ultrafast electron scattering and imaging

Sun, Xiaoyi; Sun, Shuaishuai; Ruan, Chong‐Yu

doi:10.5802/crphys.86

Cited by 5 publications

(3 citation statements)

References 281 publications

(560 reference statements)

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“…We could determine the LA mode amplitude based on the intensity modulation. 37 The ≈0.5% amplitude change, as observed in Fig. 10(b) , gives the coherent phonon amplitude at the level of 5 × 10 −4 Å.…”

Section: New Development In the Phase Precision Controlmentioning

confidence: 68%

“…The structure factor associated with the broken-symmetry CDW order,

, is given in the basis of the unmodified lattice form factor

where

denotes the position of the undistorted lattice. 37 The dynamical evolution shown in lattice and superlattice peaks are given by lattice displacement field

, depicted by two different types of lattice waves: the lattice phonons (

) or collective field modes of the broken-symmetry order (

) with momentum wavevector

and

given by

and

, referencing to the central Bragg reflection

.…”

Section: New Development In the Phase Precision Controlmentioning

confidence: 99%

See 1 more Smart Citation

Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe2 probed at 50 fs–10 fm scales

Sun,

Williams,

Sharma

et al. 2024

Structural Dynamics

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We report on the first detailed beam tests attesting the fundamental principle behind the development of high-current-efficiency ultrafast electron microscope systems where a radio frequency (RF) cavity is incorporated as a condenser lens in the beam delivery system. To allow for the experiment to be carried out with a sufficient resolution to probe the performance at the emittance floor, a new cascade loop RF controller system is developed to reduce the RF noise floor. Temporal resolution at 50 fs in full-width-at-half-maximum and detection sensitivity better than 1% are demonstrated on exfoliated 1T-TaSe2 system under a moderate repetition rate. To benchmark the performance, multi-terahertz edge-mode coherent phonon excitation is employed as the standard candle. The high temporal resolution and the significant visibility to very low dynamical contrast in diffraction signals via high-precision phase-space manipulation give strong support to the working principle for the new high-brightness femtosecond electron microscope systems.

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Section: New Development In the Phase Precision Controlmentioning

confidence: 68%

“…The structure factor associated with the broken-symmetry CDW order,

, is given in the basis of the unmodified lattice form factor

where

denotes the position of the undistorted lattice. 37 The dynamical evolution shown in lattice and superlattice peaks are given by lattice displacement field

, depicted by two different types of lattice waves: the lattice phonons (

) or collective field modes of the broken-symmetry order (

) with momentum wavevector

and

given by

and

, referencing to the central Bragg reflection

.…”

Section: New Development In the Phase Precision Controlmentioning

confidence: 99%

Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe2 probed at 50 fs–10 fm scales

Sun,

Williams,

Sharma

et al. 2024

Structural Dynamics

Self Cite

View full text Add to dashboard Cite

show abstract

“…Ultrafast structural processes that occur following excitation can be visualized [41][42][43] and cross-checked [44] adopting both real-space (imaging) and reciprocal-space (diffraction) approaches for a UTEM, providing atomic and morphological information with femtosecond time resolution. Using ultrafast selected-area electron diffraction (USAED), one can get both the mean atomic displacements of short-range order following the Debye-Waller relation (i.e., the diffraction intensity change of the main Bragg peak) and the crystal lattice change of long-range order with precision of 10 −4 nm (i.e., the position shift of the Bragg peak).…”

Section: Ultrafast Structural Dynamics and Phase Transitions Revealed...mentioning

confidence: 99%

Capturing the non-equilibrium state in light–matter–free-electron interactions through ultrafast transmission electron microscopy

Wang 汪,

Sun 孙,

Li 李

et al. 2023

Chinese Phys. B

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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 space. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photo-induced 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 beam.

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Simulation of ultrafast electron diffraction intensity under coherent acoustic phonons

Zhang,

Li,

Wang

et al. 2023

Structural Dynamics

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Ultrafast electron diffraction has been proven to be a powerful tool for the study of coherent acoustic phonons owing to its high sensitivity to crystal structures. However, this sensitivity leads to complicated behavior of the diffraction intensity, which complicates the analysis process of phonons, especially higher harmonics. Here, we theoretically analyze the effects of photoinduced coherent transverse and longitudinal acoustic phonons on electron diffraction to provide a guide for the exploitation and modulation of coherent phonons. The simulation of the electron diffraction was performed in 30-nm films with different optical penetration depths based on the atomic displacements obtained by solving the wave equation. The simulation results exhibit a complex relationship between the frequencies of the phonons and diffraction signals, which highly depends on the laser penetration depth, sample thickness, and temporal stress distribution. In addition, an intensity decomposition method is proposed to account for the in-phase oscillation and high harmonics caused by inhomogeneous excitation. These results can provide new perspectives and insights for a comprehensive and accurate understanding of the lattice response under coherent phonons.

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Toward nonthermal control of excited quantum materials: framework and investigations by ultrafast electron scattering and imaging

Abstract: Toward nonthermal control of excited quantum materials: framework and investigations by ultrafast electron scattering and imaging

Cited by 5 publications

References 281 publications

Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe2 probed at 50 fs–10 fm scales

Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe2 probed at 50 fs–10 fm scales

Capturing the non-equilibrium state in light–matter–free-electron interactions through ultrafast transmission electron microscopy

Simulation of ultrafast electron diffraction intensity under coherent acoustic phonons

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