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

Photoinduced threshold switching processes that lead to bistability and the formation of metastable phases in photoinduced phase transition of VO 2 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 M 2 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.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Michigan State Univ., East Lansing, MI (United States)
Publication Date:
Grant/Contract Number:
FG02-06ER46309
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Michigan State Univ., East Lansing, MI (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1361627

Tao, Zhensheng, Zhou, Faran, Han, Tzong-Ru T., Torres, David, Wang, Tongyu, Sepulveda, Nelson, Chang, Kiseok, Young, Margaret, Lunt, Richard R., and Ruan, Chong-Yu. The nature of photoinduced phase transition and metastable states in vanadium dioxide. United States: N. p., Web. 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. United States. 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., and Ruan, Chong-Yu. 2016. "The nature of photoinduced phase transition and metastable states in vanadium dioxide". United States. doi:10.1038/srep38514. https://www.osti.gov/servlets/purl/1361627.
@article{osti_1361627,
title = {The nature of photoinduced phase transition and metastable states in vanadium dioxide},
author = {Tao, Zhensheng and Zhou, Faran and Han, Tzong-Ru T. and Torres, David and Wang, Tongyu and Sepulveda, Nelson and Chang, Kiseok and Young, Margaret and Lunt, Richard R. and Ruan, Chong-Yu},
abstractNote = {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.},
doi = {10.1038/srep38514},
journal = {Scientific Reports},
number = 1,
volume = 6,
place = {United States},
year = {2016},
month = {12}
}