G. Sawatzky

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Frantsevich Institute for Problems of Materials Science, NAS of Ukraine

T. Devereaux

Stanford University

maayan yaari

Hadi Ebrahimnejad

University of British Columbia

Etienne Janod

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Papers by G. Sawatzky

Spectroscopic and Theoretical Estimates of Parameters in Model Hamiltonians Describing the High and Low Energy Scale Physics of Doped CuO2 Planes

Springer Series in Solid-State Sciences, 1989

In this paper we describe the determination of relevant model Hamiltonian parameters for high Tc ... more

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Electronic structure of some 3D transition-metal pyrites

Journal of Physics C: Solid State Physics, 1987

Bremsstrahlung Isochromat spectra of FeS,, NiS2, NiS, $e, and NiSe, are reported. These are the f... more Bremsstrahlung Isochromat spectra of FeS,, NiS2, NiS, $e, and NiSe, are reported. These are the first direct experimental evidence for a sharp antibonding p-like state above the Fermi level. A comparison is made with experimental results in the literature. For Fe&amp;amp;amp;amp;amp;amp;, band-structure calculations are also presented; these are in good agreement with experiment. We show that it is necessary in

Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling

Nature materials, 2016

Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring... more Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropie...

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Valence-state reflectometry of complex oxide heterointerfaces

npj Quantum Materials, 2016

Emergent phenomena in transition-metal-oxide heterostructures such as interface superconductivity... more Emergent phenomena in transition-metal-oxide heterostructures such as interface superconductivity and magnetism have been attributed to electronic reconstruction, which, however, is difficult to detect and characterise. Here we overcome the associated difficulties to simultaneously address the electronic degrees of freedom and distinguish interface from bulk effects by implementing a novel approach to resonant X-ray reflectivity (RXR). Our RXR study of the chemical and valance profiles along the polar (001) direction of a LaCoO3 film on NdGaO3 reveals a pronounced valence-state reconstruction from Co3+ in the bulk to Co2+ at the surface, with an areal density close to 0.5 Co2+ ions per unit cell. An identical film capped with polar (001) LaAlO3 maintains the Co3+ valence over its entire thickness. We interpret this as evidence for electronic reconstruction in the uncapped film, involving the transfer of 0.5e− per unit cell to the subsurface CoO2 layer at its LaO-terminated polar sur...

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Superconductivity in K[sub 3]C[sub 60] and Rb[sub 3]C[sub 60] surfaces

AIP Conference Proceedings, 2001

We present a detailed investigation of the surface electronic structure of solid K3C60 and Rb3C60... more We present a detailed investigation of the surface electronic structure of solid K3C60 and Rb3C60 in connection with their electronic transport properties. The best conducting samples with the highest superconducting transition temperature Tc have the highest density of states at the Fermi level as measured by photoemission, but the valence of the C60 ions at the surface deviates appreciable from the 3- bulk value, namely 2.5- or even 1.5-depending on the preparation procedure. Despite the large discrepancy in the electronic structure, we find, using ultra-high resolution photoemission, that these surfaces have a BCS-like superconducting gap Δ which is not reduced from the bulk value, i.e. close to the weak coupling 2Δ/kBTc=3.53 value.

Reduction of Coulomb and charge-transfer energies in oxide films on metals

Physical Review B, 1999

Using the MgO/Ag͑100͒ interface as a model system, we demonstrate that Coulomb and charge-transfe... more Using the MgO/Ag͑100͒ interface as a model system, we demonstrate that Coulomb and charge-transfer energies in oxide layers deposited on a highly polarizable medium like a metal, are reduced from their bulk values, by as much as 1.8 eV and 2.5 eV, respectively. The use of efficient image potential screening may provide a new method to alter various transition temperatures and properties of correlated oxides.

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Symmetry of charge order in cuprates

Nature Materials, 2015

Making the most of the patients ego assets

Nursing outlook, 1961

Electronic structure of clean and oxygen covered silver (110) surface

Surface Science, 1990

We use angle-resolved photoelectron spectroscopy to investigate the electronic structure of the c... more We use angle-resolved photoelectron spectroscopy to investigate the electronic structure of the clean and atomic oxygen covered Ag(110) surface. A comparison is made to results of surface band-structure calculations using a tight-binding method in a recursive layer-by-layer scheme. For the clean surface, where angle-resolved inverse photoemission data are also available, w obtain good agreement for all (except image potential) surface states. For the Ag(110)-p(2 × 1)-O surface, the electronic structure is calculated for a “buckled-row” and a “missing-row” reconstruction model. All occupied surface states are reproduced by both models where alternate silver 〈001〉 rows are displaced outward by 0.2 ± 0.2A from the first layer and the oxygens are located 0.2± 0.2 A above these. Angle-resolved inverse photoemission however would distinguish between the two reconstruction models since the unoccupied surface states are quite different. We also discuss the electronic structure of some other possible forms of oxygen adsorption on and absorption in silver single-crystal surfaces in relation to photoelectron spectroscopy.

Hole photoproduction in insulating copper oxide

Physical Review B, 1997

Basing on t − J model we calculate the k-dependence of a single hole photoproduction probability ... more

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Narrowcast Advertising Retail Metrics: A Simulation with Fuzzy Product Profitability Potential

2007 Canadian Conference on Electrical and Computer Engineering, 2007

Abstract Narrowcast advertising is becoming a prominent means to modify retail product consumptio... more Abstract Narrowcast advertising is becoming a prominent means to modify retail product consumption. This consumption is directed to maximize profit despite changes in consumer preferences and is effected by changes to the number of advertising impressions and their product content. The profitability potential of a product quantifies possible future earnings for a retail outlet and is a useful tool for retail decision makers. Common retail metrics, such as sales data, surveys of consumer product preferences, and advertising impressions, can be ...

Captology in Narrowcast Advertising: A Swarm Simulation of Persuasion Models

2006 Canadian Conference on Electrical and Computer Engineering, 2006

Page 1. CAPTOLOGY IN NARROWCAST ADVERTISING: ... Experiments investigate advertising coverage and... more

The use of cooper minima effects and resonant photoemission in the study of the electronic structure of dilute alloys

Journal of Physics F: Metal Physics, 1987

It is shown that photon energy dependent photoemission, using a synchrotron radiation source, IS ... more It is shown that photon energy dependent photoemission, using a synchrotron radiation source, IS a useful tool in studying the electronic structure of alloys. In AuNi a satellite structure at 1.9 eV is identified using a combination of cross-section effects and resonant photoemission. A model calculation is used to show that our observations are consistent with the magnitude of parameters describing the electronic behaviour in terms of correlation and hybridisation. obtained from other techniques. Recently various studies of dilute alloys of 3d metals in noble metal hosts using electron spectroscopy techniques have been

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Ultrathin oxide films on metals: new physics and new chemistry?

Thin Solid Films, 2001

Oxide thin films on metals are now currently used as model systems to study the surface propertie... more Oxide thin films on metals are now currently used as model systems to study the surface properties of highly insulating oxides by means of electron spectroscopies. However, it has been recently proposed that ultrathin oxide films and oxide-metal interfaces may actually have unprecedented intrinsic chemical-physical properties, because of image potential screening of charge fluctuations and interfacial hybridizational effects. In fact, on-site Coulomb interactions and charge transfer energies in oxide thin films on metals are reduced by as much as a few eV as compared to the bulk values, thus suggesting a large reduction of the conductivity gap and a strong enhancement of the strength of various exchange and superexchange magnetic interactions in thin layers of strongly correlated oxides on metals. Moreover, interfacial oxygen states with strong metallic character have been observed and considered responsible for an unusually high and chemical selective reactivity of oxide-metal interfaces. Some basic ideas and results connected with these intriguing interfacial phenomena will be presented and discussed taking MgO thin films on Ag(100) as a model system.

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Monovalent copper in the chalcogenide spinel CuCr2Se4

Solid State Communications, 1974

X-ray photoelectron spectra of CuCr2Se4 and some other copper and chromium containing compounds w... more X-ray photoelectron spectra of CuCr2Se4 and some other copper and chromium containing compounds were studied to reveal the valence state of the copper atom in CuCr2Se4. Binding energies of the core electrons of the constituting atoms were determined. From these data it is concluded that copper in CuCr2Se4 is monovalent.

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Cation valencies in cubic and tetragonal Mn1.9Fe1.1O4

Physics Letters A, 1972

Abstract Mossbauer effect studies on Mn1.9Fe1.1O4 indicate that the cubic to tetragonal phase tra... more

Determination of the Mechanism for Resonant Scattering inLaMnO3

Physical Review Letters, 2006

The resonant multiple Bragg x-ray diffraction is used to study the forbidden 10 4 reflection in L... more The resonant multiple Bragg x-ray diffraction is used to study the forbidden 10 4 reflection in LaMnO 3. Using the interference between the three-beam scattering and resonant scattering we can determine the phase of the resonant scattering. This phase is shown to be consistent with a model in which the resonant scattering is caused by the influence of the Mn-O bond length distortion rather than directly by the orbital ordering on the Mn 4p band structure.

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Magnon-Mediated Interactions between Fermions Depend Strongly on the Lattice Structure

Physical Review Letters, 2012

Band Structure Approach to Resonant X-Ray Scattering

Physical Review Letters, 2001

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CuK-edge resonant inelastic x-ray scattering in edge-sharing cuprates

Physical Review B, 2008

We present calculations for resonant inelastic x-ray scattering (RIXS) in edge-shared copper oxid... more We present calculations for resonant inelastic x-ray scattering (RIXS) in edge-shared copper oxide systems, such as Li2CuO2 and CuGeO3, appropriate for hard x-ray scattering such as the copper K-edge. We perform exact diagonalizations of the multi-band Hubbard model and determine the energies, orbital character and resonance profiles of excitations which can be probed via RIXS. We find excellent agreement with recent results on Li2CuO2 and CuGeO3 in the 2-7 eV photon energy loss range.

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Spectroscopic and Theoretical Estimates of Parameters in Model Hamiltonians Describing the High and Low Energy Scale Physics of Doped CuO2 Planes

Springer Series in Solid-State Sciences, 1989

In this paper we describe the determination of relevant model Hamiltonian parameters for high Tc ... more

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Electronic structure of some 3D transition-metal pyrites

Journal of Physics C: Solid State Physics, 1987