Theoretical evidence for the Peierls transition in 
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Kulmus, Kathrin; Gemming, Sibylle; Schreiber, Michael; Pashov, Dimitar; Acharya, Swagata

doi:10.1103/physrevb.104.035128

Cited by 8 publications

(3 citation statements)

References 43 publications

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“…The electrical properties of Nb oxides' are highly sensitive to the oxidation state of Nb [10]. NbO 2 has a small band gap (between 0.5 and 1.2 eV) [10] and exhibits Mott-Peierls transition at ∼1081 K [11,12] like VO 2 [13,14], whereas Nb 2 O 5 is a semiconductor with wide band gap [15].…”

Section: Introductionmentioning

confidence: 99%

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

2023

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Niobium dioxide (NbO2) exhibits metal-insulator transition (Mott transition) and show the potential for application in memristors and neuromorphic devices. Presently growth of NbO2 thin films requires high-temperature reduction of Nb2O5 films using H2 or sophisticated techniques such as molecular beam epitaxy and pulsed laser deposition. The present study demonstrates a simple chemical route of the direct growth of crystalline NbO2 films by chemical vapor deposition (CVD) using a freshly prepared Nb-hexadecylamine (Nb-HDA) complex. X-ray diffraction studies confirm the NbO2 phase with a distorted rutile body-centered-tetragonal (BCT) structure and the film grown with a highly preferred orientation on c-sapphire. X-ray photoelectron spectroscopy (XPS) confirms the +4 oxidation state. The present method offers facile growth of NbO2 films without post-reduction steps which will be assumed to be a cost-effective process for NbO2 based devices.

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Section: Introductionmentioning

confidence: 99%

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

2023

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“…Ladders are incorporated by solving a Bethe-Salpeter equation (BSE) in the particle-hole charge channel. BSE corrections to the polarizability has proven to be tremendously successful [13,14,[46][47][48][49][50][51] in explaining the optical absorption spectrum of many materials ab-initio. If the electron-hole pairs originate from strongly correlated bands, they can not disperse away and stay sufficiently close together or can even form bound (excitonic) states.…”

Section: Introductionmentioning

confidence: 99%

A Theory for Colors of Strongly Correlated Electronic Systems

Acharya¹,

Weber²,

Pashov³

et al. 2022

Preprint

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Many strongly correlated transition metal insulators are colored, even though they have large fundamental band gaps and no quasi-particle excitations in the visible range. Why such insulators possess the colors they do poses a serious challenge for any many-body theory to reliably pick up the interactions responsible for the color. We pick two archetypal cases as examples: NiO with green color and MnF2 with pink color. To explain the origin of color in these systems, we employ two kinds of advanced ab initio many body Green's function theories to investigate both optical and spin susceptibilities. The first, a perturbative theory based on low-order extensions of the GW approximation, is able to explain the color in NiO, and indeed well describe the dielectric response over the entire frequency spectrum, while the same theory is unable to explain why MnF2 is pink. We show its color originates from higher order spin-flip transitions that modify the optical response. This phenomenon is not captured by low-order perturbation theory, but it is contained in dynamical mean-field theory (DMFT), which has a dynamical spin-flip vertex that contributes to the charge susceptibility. By combining DMFT with an extension of the quasiparticle self-consistent GW approximation to provide a high-fidelity framework for the one-body Green's function, we are able to well describe the peaks in subgap charge susceptibilities in both NiO and MnF2. As a secondary outcome of this work, we establish that the one-particle properties of paramagnetic NiO and MnF2 are both well described by an adequate single Slater-determinant theory and do not require a dynamical vertex.

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“…However, it is well known that the one-particle Green's function may not be enough to describe the dielectric response. The vertex in the polarizability is a two-particle object responsible for electronhole attraction, which gives rise, e.g., to excitons and optical absorption below the fundamental gap [14][15][16][17][18][19][20] . When the excitons are weakly bound (Wannier type) they involve mostly states near the edge of the fundamental gap: they are confined to a small volume of k space and thus are spread over many lattice sites.…”

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confidence: 99%

A theory for colors of strongly correlated electronic systems

Acharya,

Pashov,

Weber

et al. 2023

Nat Commun

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Many strongly correlated transition metal insulators are colored, even though they have band gaps much larger than the highest energy photons from the visible light. An adequate explanation for the color requires a theoretical approach able to compute subgap excitons in periodic crystals, reliably and without free parameters—a formidable challenge. The literature often fails to disentangle two important factors: what makes excitons form and what makes them optically bright. We pick two archetypal cases as examples: NiO with green color and MnF2 with pink color, and employ two kinds of ab initio many body Green’s function theories; the first, a perturbative theory based on low-order extensions of the GW approximation, is able to explain the color in NiO, while the same theory is unable to explain why MnF2 is pink. We show its color originates from higher order spin-flip transitions that modify the optical response, which is contained in dynamical mean-field theory (DMFT). We show that symmetry lowering mechanisms may determine how ‘bright’ these excitons are, but they are not fundamental to their existence.

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Theoretical evidence for the Peierls transition in NbO2

Cited by 8 publications

References 43 publications

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

A Theory for Colors of Strongly Correlated Electronic Systems

A theory for colors of strongly correlated electronic systems

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Theoretical evidence for the Peierls transition in NbO2

Cited by 8 publications

References 43 publications

A new precursor route for the growth of NbO2 thin films by chemical vapor deposition

A new precursor route for the growth of NbO2 thin films by chemical vapor deposition

A Theory for Colors of Strongly Correlated Electronic Systems

A theory for colors of strongly correlated electronic systems

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Product

Resources

About

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition

A new precursor route for the growth of NbO₂ thin films by chemical vapor deposition