Article

# Femtosecond Structural Dynamics in VO 2 during an Ultrafast Solid-Solid Phase Transition

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University of California San Diego, La Jolla, California 92093-0339, USA.
(Impact Factor: 7.51). 01/2002; 87(23):237401. DOI: 10.1103/PhysRevLett.87.237401
Source: PubMed

ABSTRACT Femtosecond x-ray and visible pulses were used to probe structural and electronic dynamics during an optically driven, solid-solid phase transition in ${\mathrm{VO}}_{2}$. For high interband electronic excitation $($\sim${}5\ifmmode\times\else\texttimes\fi{}{10}^{21}{\mathrm{cm}}^{$-${}3})$, a subpicosecond transformation into the high- $T$, rutile phase of the material is observed, simultaneous with an insulator-to-metal transition. The fast time scale observed suggests that, in this regime, the structural transition may not be thermally initiated.

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Available from: Jeff A Squier, Oct 17, 2014
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• "In this photoinduced solid state phenomenon, one should single out the case of the standard yet controversial oxide VO 2 which exhibits a pure 1st order phase transition. Indeed, as reported recently by various authors, the photoinduced phase transition by femtosecond laser pulses in VO 2 has allowed shedding light not only on the so long disputed nature of the transition itself, distinguishing hence the Mott–Hubbard-like transition from the electron trapping in homopolar bonds, but also on its dynamic and the duration of the phase transition itself which was found to be of about 180 fs [18] [19]. The additional complementary recent work of Lysenko et al. [20] indicated that, upon a laser excitation, an instantaneous response in the transient reflectivity and transmission was observed followed by a relatively longer relaxation process. "
##### Article: Photoinduced Electron Spin Resonance Phenomenon in a-Cr2O3 Nanospheres
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ABSTRACT: The photoinduced phenomenon in 𝛼-Cr2O3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315 K. An X-band electron-spin resonance spectrometry was employed to probe the magnetic behavior in 𝛼-Cr2O3 under an IR illumination in the nanosecond regime. The photoinduced effect on both low and high field ESR signals appears above 280 K and is remarkably enhanced just below Neel temperature ´ 𝑇N. Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above 𝑇N of crystalline 𝛼-Cr2O3. In the antiferromagnetic phase, that is, below 𝑇N, the shift of the low field absorption could be attributed to the interaction of the light with specific Cr3+ ions located in strongly distorted sites correlated to strong ligand-field effect.
Journal of Nanomaterials 01/2015; 2015. DOI:10.1155/2015/831065 · 1.61 Impact Factor
• Source
• "In this photoinduced solid state phenomenon, one should single out the case of the standard yet controversial oxide VO 2 which exhibits a pure 1st order phase transition. Indeed, as reported recently by various authors, the photoinduced phase transition by femtosecond laser pulses in VO 2 has allowed shedding light not only on the so long disputed nature of the transition itself, distinguishing hence the Mott–Hubbard-like transition from the electron trapping in homopolar bonds, but also on its dynamic and the duration of the phase transition itself which was found to be of about 180 fs [18] [19]. The additional complementary recent work of Lysenko et al. [20] indicated that, upon a laser excitation, an instantaneous response in the transient reflectivity and transmission was observed followed by a relatively longer relaxation process. "
##### Article: Research Article Photoinduced Electron Spin Resonance Phenomenon in a-Cr2O3 Nanospheres
[Hide abstract]
ABSTRACT: The photoinduced phenomenon in α-Cr2O3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315 K. An X-band electron-spin resonance spectrometry was employed to probe the magnetic behavior in α-Cr2O3 under an IR illumination in the nanosecond regime. The photoinduced effect on both low and high field ESR signals appears above 280 K and is remarkably enhanced just below Néel temperature . Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above of crystalline α-Cr2O3. In the antiferromagnetic phase, that is, below , the shift of the low field absorption could be attributed to the interaction of the light with specific Cr3+ ions located in strongly distorted sites correlated to strong ligand-field effect.
• Source
• "In this photoinduced solid state phenomenon, one should single out the case of the standard yet controversial oxide VO 2 which exhibits a pure 1st order phase transition. Indeed, as reported recently by various authors, the photoinduced phase transition by femtosecond laser pulses in VO 2 has allowed shedding light not only on the so long disputed nature of the transition itself, distinguishing hence the Mott–Hubbard-like transition from the electron trapping in homopolar bonds, but also on its dynamic and the duration of the phase transition itself which was found to be of about 180 fs [18] [19]. The additional complementary recent work of Lysenko et al. [20] indicated that, upon a laser excitation, an instantaneous response in the transient reflectivity and transmission was observed followed by a relatively longer relaxation process. "
##### Article: Photoinduced Electron Spin Resonance Phenomenon in 𝛼-Cr2O3 Nanospheres
[Hide abstract]
ABSTRACT: The photoinduced phenomenon in 𝛼-Cr2O3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315K. An X-band electron-spin resonance spectrometry was employed to probe the magnetic behavior in 𝛼-Cr2O3 under an IR illumination in the nanosecond regime.The photoinduced effect on both low and high field ESR signals appears above 280K and is remarkably enhanced just below N´eel temperature 𝑇N. Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above 𝑇N of crystalline 𝛼-Cr2O3. In the antiferromagnetic phase, that is, below 𝑇N, the shift of the low field absorption could be attributed to the interaction of the light with specific Cr3+ ions located in strongly distorted sites correlated to strong ligand-field effect.

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