Monoclinic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:msub></mml:math>phase of VO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>: Mott-Hubbard versus band insulator

Белозеров, А. С.; Korotin, M. A.; Анисимов, В. И.; Poteryaev, A. I.

doi:10.1103/physrevb.85.045109

Cited by 77 publications

(56 citation statements)

References 60 publications

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“…The exact nature of the metal-insulator transition has remained elusive and is of continuing scientific interest; recent work has emphasized the significance of electronelectron interactions associated with a Mott-Hubbard transition and/or electron-phonon interactions associated with a Peierls mechanism. [2][3][4][5][6][7][8][9] The value of τ c can be changed by substitutional doping, for example by replacing some vanadium by tungsten, 10 and wellcrystallized W x V 1-x O 2 films with x ≈ 0.02 can have τ c ≈ 20 °C; 11 doping with atomic hydrogen is another possibility. 12 The magnitude of the resistance change at τ c depends on the degree of crystallinity, and epitaxial films can display a difference of three to four orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Namura

Suzuki

et al. 2013

Journal of Applied Physics

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Thermochromic VO 2 nanorods made by sputter deposition: Growth conditions and optical modeling. Reactive dc magnetron sputtering onto glass-based substrates yielded deposits of thermochromic VO 2 with well-developed nanorods and nanowires. Their formation was promoted by high substrate temperature (above ~500 °C), sufficient film thickness, proper inlet of the reactive gas, dispersed gold "seeds" and pronounced substrate roughness. Rutherford back scattering ascertained mass thicknesses, scanning electron microscopy depicted the nanostructures, and glancing incidence Xray diffraction proved that single-phase VO 2 was normally formed. Journal of Applied PhysicsSpectrophotometric measurements of total and diffuse transmittance and reflectance on VO 2 thin films, at room temperature and ~100 °C, allowed us to determine complex dielectric functions below and above the "critical" temperature for thermochromic switching (~68 °C). These data were then used in computations based on the Bruggeman effective medium theory applied to randomly oriented prolate spheroidal structural units to derive the optical properties of the deposits.Experimental and computed data on spectral absorptance were found to be in good qualitative agreement.

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Section: Introductionmentioning

confidence: 99%

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Namura

Suzuki

et al. 2013

Journal of Applied Physics

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“…However, it is generally agreed that the structural changes and the Peierls mechanism alone cannot be fully responsible for the insulating nature of the M 1 phase. [12][13][14][15] Much previous effort has been focused on understanding the physics behind the MIT, especially the role electron-electron correlation and electron-lattice coupling play in driving the simultaneous structural and electronic phase transition. [14,[16][17][18][19][20] Whether the insulating M 1…”

Section: Introductionmentioning

confidence: 99%

VO2: Orbital competition, magnetism, and phase stability

et al. 2012

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The relative phase stability of VO2 is one of the most fundamental issues concerning the metalinsulator transition in this material but has so far largely unexplored theoretically. We investigate the relative stability of various phases of VO2 using different levels of energy functionals within density functional theory (DFT). It is found that straightforward applications of several popular energy functionals, including the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional, result in a wrong prediction for the ground state of VO2. In particular, although the HSE and DFT+U methods are able to produce a band gap in the M1 phase, they strongly favor the formation of local magnetic moments, a result that clearly disagrees with experiments. We also examine the effect of the occupation and the redistribution of the d derived t2g (i.e., dxz, dyz and d x 2 −y 2 ) orbitals of V atoms on the calculated relative phase stability of VO2. We find that a small change in d-occupation can result in a drastically different theoretical prediction. With the introduction of an orbital-dependent potential, a complete separation between the d x 2 −y 2 derived valence band and dxz and dyz derived conduction bands in the M1 phase is achieved, resulting in a slight redistribution of the d occupation and a more faithful account of the polarization of the t2g orbitals. This slight rearrangement of the d occupation also leads to a relative phase stability of VO2 (including structural and magnetic phases) that agrees well with experiment.

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“…1 This material is known to undergo a first order metal-to-insulator transition accompanied by a crystal structure transformation, and thin films of VO 2 reversibly switch between a low-temperature (monoclinic, M1) infrared-transmitting semiconducting state and a high-temperature (rutile) infrared-reflecting metallic state at a critical temperature s c of $68 C. The underlying mechanism is connected to a Mott-Hubbard transition and/or a Peierls mechanism and is of continued scientific interest; [2][3][4][5][6][7] it was recently described as a solid-state triple point. 2 The switching of the infrared transmittance enables a modulation of the solar energy throughput, which has led to large practical interest in thermochromic VO 2 as smart switchable coatings for energy-efficient windows.…”

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confidence: 99%

Bandgap widening in thermochromic Mg-doped VO2 thin films: Quantitative data based on optical absorption

Mlyuka

Primetzhofer

et al. 2013

Applied Physics Letters

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Thermochromic Mg-doped VO2 films were deposited by reactive direct current magnetron sputtering onto heated glass and carbon substrates. Elemental compositions were inferred from Rutherford backscattering. Optical bandgaps were obtained from spectral transmittance and reflectance measurements—from both the film side and the back side of the samples—and ensuing determination of absorption coefficients. The bandgap of Mg-doped films was found to increase by 3.9 ± 0.5 eV per unit of atom ratio Mg/(Mg + V) for 0 < Mg/(Mg + V) < 0.21. The presence of ∼0.45 at. % Si enhanced the bandgap even more.

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MonoclinicM1phase of VO2: Mott-Hubbard versus band insulator

Cited by 77 publications

References 60 publications

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

VO2: Orbital competition, magnetism, and phase stability

Bandgap widening in thermochromic Mg-doped VO2 thin films: Quantitative data based on optical absorption

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