Ultrafast X-ray imaging of the light-induced phase transition in VO2

Johnson, Allan S.; Perez-Salinas, Daniel; Siddiqui, Khalid M.; Kim, Sung-Won; Choi, Sungwook; Volckaert, Klara; Majchrzak, Paulina; Ulstrup, Søren; Agarwal, Naman; Hallman, Kent A.; Haglund, Richard F.; Günther, C.; Pfau, Bastian; Eisebitt, Stefan; Backes, Dirk; Maccherozzi, Francesco; Fitzpatrick, Ann; Dhesi, S. S.; Gargiani, Pierluigi; Valvidares, Manuel; Artrith, Nongnuch; Groot, Frank M. F. de; Choi, Hyeongi; Jang, Dogeun; Katoch, Abhishek; Kwon, Soon Gu; Park, Sang Han; Kim, Hyunjung; Wall, Simon

doi:10.1038/s41567-022-01848-w

Cited by 24 publications

(12 citation statements)

References 54 publications

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“…The second process revealed in our experiments is the transformation from a transient monoclinic structure to the tetragonal R phase. Recent ultrafast X-Ray hyperspectral imaging experiments 40 observed two time constants of 132 fs and 4.75 ps, and they are not related to dilation and tilting 17 . Considering the fact that these time constants are close to the timescales we observed, it is possible that they might be related to the two processes revealed in our experiments, which would be interesting to explore in the future.…”

Section: Discussionmentioning

confidence: 96%

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Transient dynamics of the phase transition in VO2 revealed by mega-electron-volt ultrafast electron diffraction

Cheng

Chen

et al. 2023

Nat Commun

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Vanadium dioxide (VO2) exhibits an insulator-to-metal transition accompanied by a structural transition near room temperature. This transition can be triggered by an ultrafast laser pulse. Exotic transient states, such as a metallic state without structural transition, were also proposed. These unique characteristics let VO2 have great potential in thermal switchable devices and photonic applications. Although great efforts have been made, the atomic pathway during the photoinduced phase transition is still not clear. Here, we synthesize freestanding quasi-single-crystal VO2 films and examine their photoinduced structural phase transition with mega-electron-volt ultrafast electron diffraction. Leveraging the high signal-to-noise ratio and high temporal resolution, we observe that the disappearance of vanadium dimers and zigzag chains does not coincide with the transformation of crystal symmetry. After photoexcitation, the initial structure is strongly modified within 200 femtoseconds, resulting in a transient monoclinic structure without vanadium dimers and zigzag chains. Then, it continues to evolve to the final tetragonal structure in approximately 5 picoseconds. In addition, only one laser fluence threshold instead of two thresholds suggested in polycrystalline samples is observed in our quasi-single-crystal samples. Our findings provide essential information for a comprehensive understanding of the photoinduced ultrafast phase transition in VO2.

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Section: Discussionmentioning

confidence: 96%

“…However, the true nature of the phase transition is still not yet fully understood. For instance, while the SPT involves both the loss of the V-V dimerization and the lattice transformation 39,40 , the related atomic pathway has not been fully revealed 17,37 .…”

mentioning

confidence: 99%

Transient dynamics of the phase transition in VO2 revealed by mega-electron-volt ultrafast electron diffraction

Cheng

Chen

et al. 2023

Nat Commun

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“…[230], the authors establish time-resolved high harmonic generation for tracking photo-induced dynamics of the insulator-to-metal phase transitions in vanadium dioxide. Closely, related to this is the study by Johnson et al where they use time and spectrally resolved coherent X-ray imaging to track the light-induced insulator-to-metal phase transition in vanadium dioxide on the nanoscale with femtosecond time resolution [231] and also observed the ultrafast loss of lattice coherence in the light induced structural phase transition of di-Vanadium trioxide [232].…”

Section: Detection Of Strongly Correlated Systems With Hhgmentioning

confidence: 99%

Strong laser physics, non-classical light states and quantum information science

Bhattacharya¹,

Lamprou²,

Maxwell³

et al. 2023

Preprint

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directions, we report on the recent progress in the fully quantized description of intense laser-matter interaction and the methods that have been developed for the generation of non-classical light states and entangled states. Also, we discuss the future directions of non-classical light engineering using strong laser fields, and the potential applications in ultrafast and quantum information science. 4 6 Conclusions 43

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“…measured the spacial evolution of VO 2 thin films with nano‐scale resolution after excitation by using time‐ and spectrally‐resolved coherent X‐ray imaging. [ 155 ] Their result revealed a photo‐excitation induced highly‐orthorhombically‐strained rutile metallic phase and suggested the importance of spacial resolution for understanding the light‐induced phase transition. Nevertheless, those are highly debated issues and remain to be further explored.…”

Section: Ultrafast Probe and Control Of Electronic Phasesmentioning

confidence: 99%

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

2022

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or far-infrared energy region are therefore of particular importance, for the THz frequencies (1 THz≈4.1 meV) are close to the energy scales of a number of important single-particle and collective excitations of quantum material systems, for example, pairing energy gaps of superconductors, lattice vibration modes (phonons), collective spin waves (magnons), Josephson plasmon in high temperature superconductors, and binding energy of bound electron-hole pairs (excitons), [1] and they are linked to a large number of fundamental physical problems currently under intensive investigations in condensed matter physics. The information yielded from equilibrium optical measurements are usually prerequisites for understanding the nonequilibrium optical properties probed by ultrafast time-resolved spectroscopy techniques.In the last three decades, we have witnessed a rapid development in ultrafast laser and nonlinear optical techniques. The intense ultrashort optical pulses at wavelengths spanning the electromagnetic spectrum from terahertz through visible to X-ray have been generated from table-top laser sources and free-electron laser facilities. A variety of time-resolved spectroscopy techniques on the basis of pump-probe scheme have been developed. Depending on the fluence of pump pulses, photoexcitations can induce different effects and phenomena. For sufficiently weak perturbations, the photoexcitation of charge carriers does not change the free-energy landscape and the system relaxes back to the equilibrium state in a short time scale. The relaxation process is determined by the same interactions (e.g for example, electron-electron, electron-phonon) that govern the equilibrium properties. In principle, one can extract the coupling strength of electron to other degrees of freedom from the relaxation dynamics. In addition, the ultrashort laser pulse whose duration is shorter than the periodicity of targeted lattice/spin modes can trigger coherent oscillations at the corresponding frequencies of collective modes, for example, phonon, magnon, etc. with decay times that are related to the dephasing times. This enables one to detect collective-mode excitations that may not be easily accessed to or probed by other techniques.By contrast, with strong pump pulses, the photoexcitation can excite a sufficient number of electrons or drive the motion of collective mode to a large amplitude. The corresponding perturbation to the lattice/spin degrees of freedom can be large enough to modify the free-energy landscape. As a result, The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to the visible has opened a new era in the experimental investigation and manipulation of quantum materials. The generation of strong optical field in an ultrashort time scale enables the steering of quantum materials nonadiabatically, inducing novel phenomenon or creating new phases which may not have an equilibrium counterpart. Ultrafast time-resolved optical techniques have provided rich information and played an im...

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Ultrafast X-ray imaging of the light-induced phase transition in VO2

Cited by 24 publications

References 54 publications

Transient dynamics of the phase transition in VO2 revealed by mega-electron-volt ultrafast electron diffraction

Transient dynamics of the phase transition in VO2 revealed by mega-electron-volt ultrafast electron diffraction

Strong laser physics, non-classical light states and quantum information science

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

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