Electronic structure and polaronic charge distributions of Fe vacancy clusters in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mml:math>

Bernal-Villamil, Iván; Gallego, S.

doi:10.1103/physrevb.90.195126

Cited by 6 publications

(11 citation statements)

References 54 publications

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“…This result corresponds very well to the recent findings presented in Ref. [15]. In principle, the divalent and trivalent Fe cations residing in the R and I sites of the wüstite lattice are distinguishable by methods sensitive to changes in the electronic structure of valence shell (e.g.…”

Section: Electronic Structuresupporting

confidence: 92%

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Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

et al. 2015

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The influence of intrinsic Fe defects in FeO (either single cation vacancies or prototypical 4:1 vacancy clusters) on the electronic and dielectric properties is studied within the density functional theory. The importance of local Coulomb interactions at Fe atoms is highlighted and shown to be responsible for the observed insulating Mott gap in FeO which is reduced by the presence of defects. We investigate nonstoichiometric configurations of Fe1−xO with x ranging from 3 to 9% and find the aliovalent Fe cations in both the regular and interstitial lattice sites of the considered configurations. Furthermore, we show that the trivalent Fe ions are induced by both isolated and clustered Fe-vacancies and introduce the empty band states inside the insulating gap, which decreases monotonically with increasing cation vacancy concentration. The Fe1−xO systems with high defect content become metallic for small values of the Coulomb interaction U , yielding the increase in the dielectric functions and optical reflectivity at low energies in agreement with the experimental data. Due to the crystal defects, the infrared-active transverse optic phonons split and distribute over a wide range of frequencies clarifying the origin of the exceptionally large spectral linewidths of the dielectric loss functions observed for wüstite in recent experiments.

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Section: Electronic Structuresupporting

confidence: 92%

“…Recently, it was shown that polaronic distributions of charge resembling those in magnetite Fe 3 O 4 emerge for the most stable defect structures in wüstite [15].…”

Section: Introductionmentioning

confidence: 99%

Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

et al. 2015

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“…The Fe A model departs from the natural evolution of the rock- salt FeO(111) stacking to a spinel Fe 3 O 4 (111) structure, shifting one Fe cation from the outermost Fe layer to a tetrahedral coordination site (Fe A ) above the surface O plane. It also represents locally the surface environment corresponding to a 4:1 cluster of Fe vacancies 10 . As evidenced in the figure, the position of this Fe A cation relaxes to become almost coplanar to O, and the 1:1 Fe:O ratio is preserved at B1.…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies of the FeO(111) surface have led a considerable dispersion of results, partly due to the difficulties to prepare high quality samples. On one hand, the bulk form only exists at ambient conditions with a significant 5-15% of Fe vacancies, and these vacancies tend to organize in different arrangements of local spinel-like clusters 10 . Though Fe 1−x O samples can be stabilized by fast quenching, it is difficult to discern these clusters from Fe 3 O 4 inclusions, which complicates their characterization.…”

Section: Introductionmentioning

confidence: 99%

Structure and magnetism of the(2×2)-FeO(111) surface

Bernal-Villamil

Gallego

2016

Phys. Rev. B

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Based on ab initio calculations we determine the features and relative stability of different models proposed to describe the (2 × 2)-FeO(111) reconstruction. Our results suggest that both wurtzite and spinel-like environments are possible, and their coexistence explains phenomena of biphase ordering. The surface phase diagram reflects a competition of charge and magnetic compensation effects, and reveals the important influence of the substrate on the final surface structure. Though antiferromagnetic couplings are dominant, frustration and the delicate balance of surface and bulk exchange interactions lead to a net surface magnetization that accounts for the large measured values.

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“…6c), four Fe oct 2+ cations are replaced by one Fe tet 3+ interstitial. 41 Using this terminology, the SCV reconstruction can be viewed as an ordered array of subsurface 2 : 1 defect clusters. The cation-deficient structure at the Fe 3 O 4 (001) surface has particularly important consequences for the adsorption of 3d transition metals.…”

Section: Materials With Cation Vacancies: Iron Oxidesmentioning

confidence: 99%

Surface point defects on bulk oxides: atomically-resolved scanning probe microscopy

et al. 2017

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Metal oxides are abundant in nature and they are some of the most versatile materials for applications ranging from catalysis to novel electronics. The physical and chemical properties of metal oxides are dramatically influenced, and can be judiciously tailored, by defects. Small changes in stoichiometry introduce so-called intrinsic defects, e.g., atomic vacancies and/or interstitials. This review gives an overview of using Scanning Probe Microscopy (SPM), in particular Scanning Tunneling Microscopy (STM), to study the changes in the local geometric and electronic structure related to these intrinsic point defects at the surfaces of metal oxides. Three prototypical systems are discussed: titanium dioxide (TiO), iron oxides (FeO), and, as an example for a post-transition-metal oxide, indium oxide (InO). Each of these three materials prefers a different type of surface point defect: oxygen vacancies, cation vacancies, and cation adatoms, respectively. The different modes of STM imaging and the promising capabilities of non-contact Atomic Force Microscopy (nc-AFM) techniques are discussed, as well as the capability of STM to manipulate single point defects.

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Electronic structure and polaronic charge distributions of Fe vacancy clusters inFe1−xO

Cited by 6 publications

References 54 publications

Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

Influence of isolated and clustered defects on electronic and dielectric properties of wüstite

Structure and magnetism of the(2×2)-FeO(111) surface

Surface point defects on bulk oxides: atomically-resolved scanning probe microscopy

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