The nature of photoinduced phase transition and metastable states in vanadium dioxide

Zhensheng Tao, Faran Zhou, Tzong Ru T Han, David Torres, Tongyu Wang, Nelson Sepulveda, Kiseok Chang, Margaret Young, Richard R. Lunt, Chong Yu Ruan

Research output: Contribution to journalArticle

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Abstract

Photoinduced threshold switching processes that lead to bistability and the formation of metastable phases in photoinduced phase transition of VO2 are elucidated through ultrafast electron diffraction and diffusive scattering techniques with varying excitation wavelengths. We uncover two distinct regimes of the dynamical phase change: A nearly instantaneous crossover into an intermediate state and its decay led by lattice instabilities over 10 ps timescales. The structure of this intermediate state is identified to be monoclinic, but more akin to M2 rather than M1 based on structure refinements. The extinction of all major monoclinic features within just a few picoseconds at the above-threshold-level (∼20%) photoexcitations and the distinct dynamics in diffusive scattering that represents medium-range atomic fluctuations at two photon wavelengths strongly suggest a density-driven and nonthermal pathway for the initial process of the photoinduced phase transition. These results highlight the critical roles of electron correlations and lattice instabilities in driving and controlling phase transformations far from equilibrium.

LanguageEnglish (US)
Article number38514
JournalScientific Reports
Volume6
DOIs
StatePublished - Dec 16 2016

Profile

dioxides
metastable state
vanadium
thresholds
photoexcitation
scattering
wavelengths
phase transformations
crossovers
extinction
electron diffraction
photons
decay
excitation
electrons

ASJC Scopus subject areas

  • General

Cite this

The nature of photoinduced phase transition and metastable states in vanadium dioxide. / Tao, Zhensheng; Zhou, Faran; Han, Tzong Ru T; Torres, David; Wang, Tongyu; Sepulveda, Nelson; Chang, Kiseok; Young, Margaret; Lunt, Richard R.; Ruan, Chong Yu.

In: Scientific Reports, Vol. 6, 38514, 16.12.2016.

Research output: Contribution to journalArticle

Tao Z, Zhou F, Han TRT, Torres D, Wang T, Sepulveda N et al. The nature of photoinduced phase transition and metastable states in vanadium dioxide. Scientific Reports. 2016 Dec 16;6. 38514. Available from, DOI: 10.1038/srep38514
Tao, Zhensheng ; Zhou, Faran ; Han, Tzong Ru T ; Torres, David ; Wang, Tongyu ; Sepulveda, Nelson ; Chang, Kiseok ; Young, Margaret ; Lunt, Richard R. ; Ruan, Chong Yu. / The nature of photoinduced phase transition and metastable states in vanadium dioxide. In: Scientific Reports. 2016 ; Vol. 6.
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