Electron correlation and magnetism at the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="normal">La</mml:mi><mml:mi mathvariant="normal">Al</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="normal">Sr</mml:mi><mml:mi mathvariant="normal">Ti</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>interface: A DFT+

Lechermann, Frank; Boehnke, Lewin; Grieger, Daniel; Piefke, Christoph

doi:10.1103/physrevb.90.085125

Cited by 37 publications

(61 citation statements)

References 57 publications

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“…In the latter category, electrons donated by oxygen vacancies near the interface partly contribute to the conduction band and partly to forming localized states orbiting neighboring Ti sites. Correlations are required to produce a magnetic instability [76,30,77] (see also Ref. [70]).…”

Section: Bulk and Interface Superconductivitymentioning

confidence: 99%

Interface superconductivity

Gariglio

Gabay

Mannhart

et al. 2015

Physica C: Superconductivity and its Applications

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Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO 3 and SrTiO 3 .We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO 3 and the interface system and the possible role of the interfacially induced Rashba type spin-orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high T c in a monolayer of FeSe deposited on SrTiO 3 .

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Section: Bulk and Interface Superconductivitymentioning

confidence: 99%

Interface superconductivity

Gariglio

Gabay

Mannhart

et al. 2015

Physica C: Superconductivity and its Applications

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“…However creating an oxygen vacancy (OV) breaks the bond between Ti-3d(e g ) and O-2p. It has been shown [14][15][16][17][18][19][20][21] that as a result also 3d(e g ) spectral weight appears just below the Fermi level ε F of the established metallic state. Investigations based on density functional theory (DFT) identify this e g weight as associated with an 'in-gap' level due to the vacancy-induced crystal-field lowering.…”

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confidence: 99%

Electron dichotomy on theSrTiO3defect surface augmented by many-body effects

et al. 2016

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In a common paradigm, the electronic structure of condensed matter is divided into weakly and strongly correlated compounds. While conventional band theory usually works well for the former class, many-body effects are essential for the latter. Materials like the familiar SrTiO3 compound that bridge or even abandon this characterization scheme are highly interesting. Here it is shown by means of combining density functional theory with dynamical-mean field theory that oxygen vacancies on the STO (001) surface give rise to a dichotomy of weakly-correlated t2g low-energy quasiparticles and localized 'in-gap' states of dominant eg character with subtle correlation signature. We furthermore touch base with recent experimental work and study the surface instability towards magnetic order.The SrTiO 3 (STO) compound has long been known for its paraelectric [1], semiconducting [2] and superconducting properties [3]. Renewed interest is fostered by the findings of a conducting two-dimensional electron system (2DES) on the STO surface [4,5], of intricate magnetic response [6], as well as due to its intriguing role as a prominent building block in novel oxide heterostructures ([7, 8], see e.g. [9, 10] reviews). In this respect, several experiments [4,5,[11][12][13] point towards the importance of oxygen vacancies for the plethora of physics emerging from the inconspicuous bulk band insulator.Stoichiometric strontium titanate is rather unsusceptible to electronic correlations due to nominal Ti 4+ (3d 0 ) valence. However, doping transforms STO into a material with potential for salient signatures of correlation effects. Usually the competition between electron localization and itinerancy in materials can be traced back to the interacting many-body system at stoichiometry. In doped STO, in contrast, defects have to build up the general correlated electronic structure from localized states affecting the low-energy quasiparticle (QP) nature beyond a conventional Anderson-model perspective.The orbital character, filling, correlation strength and mobility of the key electronic states in doped STO is of main interest. In principle, electron doping as introduced by oxygen vacancies could fill the empty Ti-3d(t 2g ) states at low energy. However creating an oxygen vacancy (OV) breaks the bond between Ti-3d(e g ) and O-2p. It has been shown [14][15][16][17][18][19][20][21] that as a result also 3d(e g ) spectral weight appears just below the Fermi level ε F of the established metallic state. Investigations based on density functional theory (DFT) identify this e g weight as associated with an 'in-gap' level due to the vacancy-induced crystal-field lowering. Depending on the local structural deformation, Ti charging, vacancy concentration and energy distance to ε F , that spectral feature may also be interpreted as a small polaron. The latter is here defined by the localization of one electron at an isolated Ti site, i.e. forming Ti 3+ , with sizable distortion of the surrounding oxygen octahedron and binding energy ∼ −1eV [22]. Rec...

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“…Since an oxygen vacancy (OV) in SrTiO 3 singularly modifies the electronic structure on the local level, i.e., from Ti(d 0 ) towards Ti(d 1 ), we follow here a twofold supercell strategy to assess the dense and dilute defect cases. Realistic superlattice DMFT calculations are performed for the dense defect limit [95] and a derived model Hamiltonian is applied to a large real-space lattice to treat the crossover to dilute defect scenarios [96]. Figure 11a shows the used inplane-doubled dense defect n-type supercell, with OVs in the TiO 2 layer right at the interface, whereby one out of four oxygen sites is vacant.…”

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confidence: 99%

Influence of oxygen vacancies on two-dimensional electron systems at SrTiO3-based interfaces and surfaces

Sing

Jeschke

Lechermann

et al. 2017

Eur. Phys. J. Spec. Top.

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Abstract. The insulator SrTiO 3 can host high-mobility twodimensional electron systems on its surfaces and at interfaces with other oxides. While for the bare surface a two-dimensional electron system can only be induced by oxygen vacancies, it is believed that the metallicity of heterostructure interfaces as in LaAlO 3/SrTiO3 is caused by other mechanisms related to the polar discontinuity at the interface. Based on calculations using density functional and dynamical mean-field theory as well as on experimental results using photoemission spectroscopy we elucidate the role of oxygen vacancies, thereby highlighting their importance for the electronic and magnetic properties of the systems under study.

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Electron correlation and magnetism at theLaAlO3/SrTiO3interface: A DFT+

Cited by 37 publications

References 57 publications

Interface superconductivity

Interface superconductivity

Electron dichotomy on theSrTiO3defect surface augmented by many-body effects

Influence of oxygen vacancies on two-dimensional electron systems at SrTiO3-based interfaces and surfaces

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