Electron correlations and electron-lattice interactions in the metal-insulator, ferroelastic transition in V<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>: A thermodynamical study

Paquet, D.; Leroux-Hugon, P.

doi:10.1103/physrevb.22.5284

Cited by 118 publications

(92 citation statements)

References 42 publications

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“…This T -driven MIT has attracted intense scrutiny: because of the additional complication of the antiferroelectric displacement of the V O 6 octahedra in a correlated system, an unambiguous characterization of the MIT (relative importance of MottHubbard versus Peierls dimerization) is somewhat difficult. Various observations have been cited in support of both scenarios [1], and theoretical models detailing the importance of these effects have been proposed [6,7].…”

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confidence: 99%

VO ₂ : A two-fluid incoherent metal?

2005

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We present ab initio LDA+DMFT results for the many-particle density of states of V O2 on the metallic side of the strongly first-order (T -driven) insulator-metal transition. In strong contrast to LDA predictions, there is no remnant of even correlated Fermi liquid behavior in the correlated metal. Excellent quantitative agreement with published photoemission and X-ray absorption experiments is found in the metallic phase. We argue that the absence of FL-quasiparticles provides a natural explanation for the bad-metallic transport for T > 340 K. Based on this agreement, we propose that the I-M transition in V O2 is an orbital-selective Mott transition, and point out the relevance of orbital resolved one-electron and optical spectroscopy to resolve this outstanding issue. A detailed understanding of the above cases is still somewhat elusive. In particular, it is still unclear whether the MIT is orbital selective, i.e., whether different orbital-resolved densities-of-states (DOS) are gapped (driving the Mott insulating state) at different values of U, U ′ (defined below) or whether there is a single (common) Mott transition at a critical interaction strength [3,4]. Conflicting results, even for the same system, and within the same (d = ∞) approximation [4] have been obtained, necessitating more work to resolve this issue.In this communication, we address precisely this issue in vanadium dioxide (V O 2 ). Using the state-of-the-art LDA+DMFT [5] technique, we first show how excellent quantitative agreement with the full, local one-electron spectral function is achieved using LDA+DMFT(IPT). We then build on this agreement, claiming that the MIT in V O 2 is orbital selective, and represents a concrete, ab initio realization of the two-fluid scenario for MIT in strongly correlated systems.V O 2 shows a spectacular MIT at T = 340 K from a low-T monoclinic, Mott insulating phase with spin dimerization along the crystallographic c-axis to a local moment paramagnetic metallic phase. This T -driven MIT has attracted intense scrutiny: because of the additional complication of the antiferroelectric displacement of the V O 6 octahedra in a correlated system, an unambiguous characterization of the MIT (relative importance of MottHubbard versus Peierls dimerization) is somewhat difficult. Various observations have been cited in support of both scenarios [1], and theoretical models detailing the importance of these effects have been proposed [6,7].One-electron spectroscopies constitute a reliable fingerprint of the changes in the single-particle spectral

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VO ₂ : A two-fluid incoherent metal?

2005

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“…However, a precise quantitative understanding of how this scheme is realized-in particular the roles of electronic correlations and the structural instability in the MIT-remains a matter of debate. [15][16][17][18] A complete understanding of this correlated system is necessary to predict and control the emergent properties as a function of external parameters.…”

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Modification of electronic structure in compressively strained vanadium dioxide films

Huffman

Hollingshad

et al. 2015

Phys. Rev. B

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Vanadium dioxide (VO 2 ) undergoes a phase transition between an insulating monoclinic (M 1 ) phase and a conducting rutile phase. Like other correlated electron systems, the properties of VO 2 can be extremely sensitive to small changes in external parameters such as strain. In this work, we investigate a compressively strained VO 2 film grown on [001] quartz substrate in which the phase transition temperature (T c ) has been depressed to 325K from the bulk value of 340K. Infrared and optical spectroscopy reveals that the lattice dynamics of this strained film are very similar to unstrained VO 2 . However, some of the electronic inter-band transitions of the strained VO 2 film are significantly shifted in energy from those in unstrained VO 2 . That the lattice dynamics remain largely unchanged, while the T c and some of the electronic inter-band transitions differ substantially from the bulk values highlight the role of electronic correlations in driving this metal-insulator phase transition.

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“…The issue is whether the insulating behavior in the low-T phase derives directly from the Peierls distortion 3 or from electron localization and the consequent increase in electron-electron repulsion. 4,5 Recently, a theoretical study by Wentzcovitch et al has revived attention into this four-decade-long debate, 6 suggesting that the former mechanism may be dominant, i.e., the low-T phase may be bandlike and the transition structurally driven. New controversy has resulted 7,8 and the problem is yet to be settled experimentally.…”

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Evidence for a structurally-driven insulator-to-metal transition inVO2: A view from the ultrafast timescale

et al. 2004

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We apply ultrafast spectroscopy to establish a time-domain hierarchy between structural and electronic effects in a strongly correlated electron system. We discuss the case of the model system VO 2 , a prototypical nonmagnetic compound that exhibits cell doubling, charge localization, and a metal-insulator transition below 340 K. We initiate the formation of the metallic phase by prompt hole photo-doping into the valence band of the low-T insulator. The insulator-to-metal transition is, however, delayed with respect to hole injection, exhibiting a bottleneck time scale, associated with the phonon connecting the two crystallographic phases. This structural bottleneck is observed despite faster depletion of the d bands and is indicative of important bandlike character for this controversial insulator. Correlated electron materials exhibit remarkable effects, ranging from metal-insulator transitions to nonconventional (high temperature) superconductivity. The subtle interplay between atomic structure, charge, spin, and orbital dynamics is responsible for many of the critical phenomena observed. 1 Importantly, because "simultaneous" changes in more than one degree of freedom are often observed as chemical doping or external parameters are tuned across critical values, time-integrated spectroscopies are unable to uniquely assign cause-effect relationships.Here, we demonstrate that time-resolved spectroscopy can instead be applied to overcome such ambiguities. We study the case of nonmagnetic VO 2 , a controversial, strongly correlated compound that exhibits cell doubling in "concomitance" with electron localization and a metal-insulator transition below 340 K 2 (see Fig. 1). The issue is whether the insulating behavior in the low-T phase derives directly from the Peierls distortion 3 or from electron localization and the consequent increase in electron-electron repulsion. 4,5 Recently, a theoretical study by Wentzcovitch et al. has revived attention into this four-decade-long debate, 6 suggesting that the former mechanism may be dominant, i.e., the low-T phase may be bandlike and the transition structurally driven. New controversy has resulted 7,8 and the problem is yet to be settled experimentally.Previous time-resolved optical 9 and x-ray diffraction 10 experiments in this compound demonstrated that impulsive photoexcitation of the low-T monoclinic insulator causes an ultrafast transition in both the electronic properties and the atomic structural arrangement. However, it was not clear whether the system becomes metallic due to the change in symmetry of the unit cell or to the prompt creation of holes, causing the closure of a Mott gap. We have now performed optical experiments with 15 fs resolution, and we report evidence of a limiting structural time scale for the formation of the metallic phase. This delay is observed despite much faster hole doping into the correlated d band. Such bottleneck time originates from the coherent optical-phonon distortions in the excited state of the system, mapping onto the crystal...

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Electron correlations and electron-lattice interactions in the metal-insulator, ferroelastic transition in VO2: A thermodynamical study

Cited by 118 publications

References 42 publications

VO ₂ : A two-fluid incoherent metal?

VO ₂ : A two-fluid incoherent metal?

Modification of electronic structure in compressively strained vanadium dioxide films

Evidence for a structurally-driven insulator-to-metal transition inVO2: A view from the ultrafast timescale

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Electron correlations and electron-lattice interactions in the metal-insulator, ferroelastic transition in VO2: A thermodynamical study

Cited by 118 publications

References 42 publications

VO 2 : A two-fluid incoherent metal?

VO 2 : A two-fluid incoherent metal?

Modification of electronic structure in compressively strained vanadium dioxide films

Evidence for a structurally-driven insulator-to-metal transition inVO2: A view from the ultrafast timescale

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VO ₂ : A two-fluid incoherent metal?

VO ₂ : A two-fluid incoherent metal?