Electron-electron correlations in Raman spectra of VO2

Goncharuk, I. N.; Ilinskiy, A. V.; Kvashenkina, O. E.; Shadrin, E. B.

doi:10.1134/s1063783413010149

Cited by 14 publications

(9 citation statements)

References 31 publications

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“…5 displays the Raman spectra of the sapphire substrate, the as-grown, discharge and annealed VO 2 films. While the as-grown film shows a metallic-like behavior with no spectral features (akin to the VO 2 R phase), the annealed and discharge VO 2 samples exhibit Raman spectra indicative of a high quality monoclinic M1 VO 2 phase with P 2 1 /c symmetry [48][49][50] which are consistent with previous reports on VO 2 micro-crystalline thin films and single-crystal microbeams [51][52][53] . The M1 phase is identified by the ω v1 and ω v2 modes at 195 cm −1 and 225 cm −1 , respectively, associated with the V-V lattice motion while the rest of the peaks (including the dominant broad ω 0 phonon frequency which peaks at ∼616 cm −1 ) are assigned to V-O vibrational modes 48,51,53 .…”

Section: Vibrational Propertiessupporting

confidence: 88%

“…The Raman signature of the sapphire substrate is weak, but non zero, in the VO 2 films, indicating that the entire film's volume was probed by the incident radiation. The presence of the 147 cm −1 peak was assigned to a Raman Ag symmetry mode [48][49][50] associated with soft phonons while the broad peak at 616 cm −1 is a superposition of the 616 cm −1 peak with Ag sym-metry, the 661 cm −1 and 588 cm −1 Raman peaks with Bg symmetry (although the last one was often assigned to the Ag mode) 50,54 (inset in Fig. 5) .…”

Section: Vibrational Propertiesmentioning

confidence: 99%

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Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation

Théry¹,

Boulle²,

Crunteanu³

et al. 2017

Journal of Applied Physics

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Large area (up to 4 squared inches) epitaxial VO 2 films, with a uniform thickness and exhibiting an abrupt metal-insulator transition with a resistivity ratio as high as 2.85 × 10 4 have been grown on (001)-oriented sapphire substrates by electron beam evaporation. The lattice distortions (mosaicity) and the level of strain in the films have been assessed by X-ray diffraction. It is demonstrated that the films grow in a domain-matching mode where distortions are confined close to the interface which allows to grow high-quality materials despite the high film-substrate lattice mismatch. It is further shown that a post-deposition high-temperature oxygen annealing step is crucial to ensure the correct film stoichiometry and provide the best structural and electrical properties. Alternatively, it is possible to obtain high quality films with an RF discharge during deposition, which hence do not require the additional annealing step. Such films exhibit similar electrical properties and only slightly degraded structural properties.

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Section: Vibrational Propertiessupporting

confidence: 88%

Section: Vibrational Propertiesmentioning

confidence: 99%

Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation

Théry¹,

Boulle²,

Crunteanu³

et al. 2017

Journal of Applied Physics

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“…Ω(q R ) measured in the metallic rutile phase has a frequency, ∼13 meV, smaller than the frequency of the Raman active modes measured in the insulating M 1 phase [146,[159][160][161][162][163]. Among these Raman modes, the lowest energy mode, ω Ag (Γ) = 18 meV, exhibits an anomalous thermal variation.…”

Section: Lattice Dynamics At the Mitmentioning

confidence: 88%

“…The lowest frequency phonon branch measured in metallic VO 2 is significantly damped, especially along the R-A-M direction [147]. Heavily damped zone center phonon modes are also found by Raman scattering in the R phase [159,161,163]. There, it has been suggested [163] that the broad Raman response of metallic VO 2 can be accounted by scattering process in strongly correlated materials.…”

Section: Lattice Dynamics At the Mitmentioning

confidence: 98%

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Basic aspects of the metal–insulator transition in vanadium dioxide VO2: a critical review

Pouget¹

2021

Comptes Rendus. Physique

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Enhanced Electron Correlation and Significantly Suppressed Thermal Conductivity in Dirac Nodal‐Line Metal Nanowires by Chemical Doping

et al. 2022

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Enhancing electron correlation in a weakly interacting topological system has great potential to promote correlated topological states of matter with extraordinary quantum properties. Here, the enhancement of electron correlation in a prototypical topological metal, namely iridium dioxide (IrO2), via doping with 3d transition metal vanadium is demonstrated. Single‐crystalline vanadium‐doped IrO2 nanowires are synthesized through chemical vapor deposition where the nanowire yield and morphology are improved by creating rough surfaces on substrates. Vanadium doping leads to a dramatic decrease in Raman intensity without notable peak broadening, signifying the enhancement of electron correlation. The enhanced electron correlation is further evidenced by transport studies where the electrical resistivity is greatly increased and follows an unusual T$\sqrt T $ dependence on the temperature (T). The lattice thermal conductivity is suppressed by an order of magnitude via doping even at room temperature where phonon‐impurity scattering becomes less important. Density functional theory calculations suggest that the remarkable reduction of thermal conductivity arises from the complex phonon dispersion and reduced energy gap between phonon branches, which greatly enhances phase space for phonon–phonon Umklapp scattering. This work demonstrates a unique system combining 3d and 5d transition metals in isostructural materials to enrich the system with various types of interactions.

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Electron-electron correlations in Raman spectra of VO2

Cited by 14 publications

References 31 publications

Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation

Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation

Basic aspects of the metal–insulator transition in vanadium dioxide VO2: a critical review

Enhanced Electron Correlation and Significantly Suppressed Thermal Conductivity in Dirac Nodal‐Line Metal Nanowires by Chemical Doping

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