The metal-nonmetal transition

Mott, N. F.; Zinamon, Z.

doi:10.1088/0034-4885/33/3/302

Cited by 183 publications

(52 citation statements)

References 155 publications

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“…Our results address longstanding debates over the role of magnetism and crystal structure at the insulator-metal transition 1,2,4,5,24 , while at the same time raising questions about quantum phase transitions in the presence of strong electron correlations. The broad regime of phase coexistence that we observe while tuning U/W adds to a growing list of correlated electron systems that exhibit phase coexistence around a first order quantum phase transition 25 .…”

Section: Discussionsupporting

confidence: 53%

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Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

et al. 2011

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We use synchrotron x-ray diffraction and electrical transport under pressure to probe both the magnetism and the structure of single crystal NiS2 across its Mott-Hubbard transition. In the insulator, the low-temperature antiferromagnetic order results from superexchange among correlated electrons and couples to a (1/2, 1/2, 1/2) superlattice distortion. Applying pressure suppresses the insulating state, but enhances the magnetism as the superexchange increases with decreasing lattice constant. By comparing our results under pressure to previous studies of doped crystals we show that this dependence of the magnetism on the lattice constant is consistent for both band broadening and band filling. In the high pressure metallic phase the lattice symmetry is reduced from cubic to monoclinic, pointing to the primary influence of charge correlations at the transition. There exists a wide regime of phase separation that may be a general characteristic of correlated quantum matter.

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Section: Discussionsupporting

confidence: 53%

“…3), where the four-fold splitting of the (2, 2, 0) peak only can be explained by a symmetry of monoclinic or lower. Constraining the symmetry to monoclinic, we obtain (to a 95% confidence level) a = 5.5748(9)Å, b = c = 5.5853(6)Å, β = 89.949 (1) o at 3.86 GPa. The four-fold splitting of (2, 1, 1) at 0.85 GPa (Fig.…”

Section: Lattice Structure Under Pressurementioning

confidence: 91%

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

et al. 2011

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“…They can be better ascribed to some thermally activated motion of charge carriers. The reason is that the bare hopping amplitude and bandwidth is strongly reduced due to the translation of a polaronic lattice deformation associated with electron motion 39,40 . If the reduced bandwidth is smaller than the energy of polarization phonons (typically 70 meV in magnetite), small polaron hopping is expected 41 .…”

Section: Magnetotransport Propertiesmentioning

confidence: 99%

EpitaxialZnxFe3−xO4thin films: A spintronic material with tunable electrical and magnetic properties

et al. 2009

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The ferrimagnetic spinel oxide ZnxFe3−xO4 combines high Curie temperature and spin polarization with tunable electrical and magnetic properties, making it a promising functional material for spintronic devices. We have grown epitaxial ZnxFe3−xO4 thin films (0 ≤ x ≤ 0.9) on MgO(001) substrates with excellent structural properties both in pure Ar atmosphere and an Ar/O2 mixture by laser molecular beam epitaxy and systematically studied their structural, magnetotransport and magnetic properties. We find that the electrical conductivity and the saturation magnetization can be tuned over a wide range (10 2 . . . 10 4 Ω −1 m −1 and 1.0 . . . 3.2 µB/f.u. at room temperature) by Zn substitution and/or finite oxygen partial pressure during growth. Our extensive characterization of the films provides a clear picture of the underlying physics of the spinel ferrimagnet ZnxFe3−xO4 with antiparallel Fe moments on the A and B sublattice: (i) Zn substitution removes both Fe 3+ A moments from the A sublattice and itinerant charge carriers from the B sublattice, (ii) growth in finite oxygen partial pressure generates Fe vacancies on the B sublattice also removing itinerant charge carriers, and (iii) application of both Zn substitution and excess oxygen results in a compensation effect as Zn substitution partially removes the Fe vacancies. Both electrical conduction and magnetism is determined by the density and hopping amplitude of the itinerant charge carriers on the B sublattice, providing electrical conduction and ferromagnetic double exchange between the mixed-valent Fe

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“…Vanadium sesquioxide (V 2 O 3 ) is one such oxide, transforming from the antiferromagnetic, insulating monoclinic phase to the paramagnetic, metallic corundum phase at 170 K. [1][2][3] This phase transformation is of great fundamental importance due to its model Mott-Hubbard transition behavior. 4 Recently, a metastable phase of V 2 O 3 with a cubic, bixbyite structure was discovered. 5 This new polymorph has since been the subject of several studies, both fundamental and applied, including its proposed use as a p-type conductor and battery electrode.…”

Section: Introductionmentioning

confidence: 99%

Oxygen Incorporation and Release in Metastable Bixbyite V₂O₃ Nanocrystals

2016

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A new, metastable polymorph of V 2 O 3 with a bixbyite structure was recently stabilized in colloidal nanocrystal form. Here, we report the reversible incorporation of oxygen in this material, which can be controlled by varying temperature and oxygen partial pressure. Based on X-ray diffraction (XRD) and thermogravimetric analysis, we find that oxygen occupies interstitials sites in the bixbyite lattice. Two oxygen atoms per unit cell can be incorporated rapidly and with minimal changes to the structure, while the addition of three or more oxygen atoms destabilizes the structure, resulting in a phase change that can be reversed upon oxygen removal. Density functional theory (DFT) supports the reversible occupation of interstitial sites in bixbyite by oxygen and the 1.1 eV barrier to oxygen diffusion predicted by DFT matches the activation energy of the oxidation process derived from observations by in situ XRD. Thus, the observed rapid oxidation kinetics are facilitated by short diffusion paths through the bixbyite nanocrystals. Due to the exceptionally low temperatures of oxidation and reduction, this earthabundant material is proposed for use in oxygen storage applications.The oxides of vanadium are known for both their structural complexity and fascinating properties, as manifested in the many stable and metastable phases and phase transitions that exist in these materials. Vanadium sesquioxide (V 2 O 3 ) is one such oxide, transforming from the antiferromagnetic, insulating monoclinic phase to the paramagnetic, metallic corundum phase at 170 K. [1][2][3] This phase transformation is of great fundamental importance due to its model Mott-Hubbard transition behavior. 4 Recently, a metastable phase of V 2 O 3 with a cubic, bixbyite structure was discovered. 5 This new polymorph has since been the subject of several studies, both fundamental and applied, including its proposed use as a p-type conductor and battery electrode. 6,7 Synthesizing V 2 O 3 nanocrystals stabilizes the metastable phase and allowed us, in 2013, to prepare phase pure bixbyite. 8 Using our colloidal synthetic method, we now demonstrate low temperature, reversible oxidation and reduction of bixbyite V 2 O 3 nanocrystals, a phenomenon which could be harnessed for oxygen storage.The bixbyite structure has a body-centered cubic lattice with space group Ia-3. Often described as anion deficient fluorite, bixbyite is comparable to a 2 x 2 x 2 fluorite supercell with a quarter of the anions removed, as demonstrated in Figure 1. These vacated sites are the 16c Wyckoff positions in the Ia-3 space group, which are inherently unfilled in bixbyite. 9 Cations in the bixbyite structure populate two symmetry inequivalent positions-the 8b and 24d Wyckoff positions, otherwise known as b-and d-sites,

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The metal-nonmetal transition

Cited by 183 publications

References 155 publications

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

EpitaxialZnxFe3−xO4thin films: A spintronic material with tunable electrical and magnetic properties

Oxygen Incorporation and Release in Metastable Bixbyite V₂O₃ Nanocrystals

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The metal-nonmetal transition

Cited by 183 publications

References 155 publications

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

EpitaxialZnxFe3−xO4thin films: A spintronic material with tunable electrical and magnetic properties

Oxygen Incorporation and Release in Metastable Bixbyite V2O3 Nanocrystals

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Oxygen Incorporation and Release in Metastable Bixbyite V₂O₃ Nanocrystals