Interface relaxation and electrostatic charge depletion in the oxide heterostructure LaAlO
                    <sub>3</sub>
                    /SrTiO
                    <sub>3</sub>

Schwingenschlögl, Udo; Schuster, C.

doi:10.1209/0295-5075/86/27005

Cited by 51 publications

(46 citation statements)

References 33 publications

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“…To vary the dopant concentration from x ¼ 12.5% to 50% in SrTi 1-x Nb x O 3 , the supercell approach is used [23][24][25][26] with a 2 Â 2 Â 6 supercell (120 atoms in total) of the primitive cubic unit cell, where 4 STO layers are considered to be the substrate (see the structure in Fig. 1).…”

Section: B Computationalmentioning

confidence: 99%

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Özdoğan

Kahaly

Kumar

et al. 2012

Journal of Applied Physics

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We study epitaxial SrTiO3 interfaced with Nb-doped SrTi1-xNbxO3 (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We obtain a monotonous increase of the carrier density with the Nb concentration. The results are confirmed by experiments for SrTi0.88Nb0.12O3 and SrTi0.8Nb0.2O3, demonstrating the predictive power and limitations of our theoretical approach. We also show that the Seebeck coefficient decreases monotonously with increasing temperature.

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Section: B Computationalmentioning

confidence: 99%

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Özdoğan

Kahaly

Kumar

et al. 2012

Journal of Applied Physics

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“…The creation of metallic states is intimately connected to the structural relaxation. 4 The high mobility of the charge carriers at this interface has initiated many investigations, 5,6 as did the discovery of superconductivity at low temperature. 7 However, despite huge experimental and theoretical efforts, many aspects of the physical picture of the LaAlO 3 /SrTiO 3 (LAO/STO) interface remain open.…”

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Charge transfer mechanism for the formation of metallic states at the KTaO3/SrTiO3interface

2011

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The electronic and optical properties of the KTaO 3 /SrTiO 3 heterointerface are analyzed by the full-potential linearized augmented plane-wave approach of density functional theory. Optimization of the atomic positions points at subordinate changes in the crystal structure and chemical bonding near the interface, which is due to a minimal lattice mismatch. The creation of metallic interface states thus is not affected by structural relaxation but can be explained by charge transfer between transition metal and oxygen atoms. It is to be expected that a charge transfer is likewise important for related interfaces such as LaAlO 3 /SrTiO 3 . The KTaO 3 /SrTiO 3 system is ideal for disentangling the complex behavior of metallic interface states, since almost no structural relaxation takes place. During the past decade, heterointerfaces based on perovskite transition metal oxides have attracted a great deal of attention due to the discovery of remarkable electronic and magnetic properties. They are of special importance for device applications, such as field effect transistors, bipolar transistors, and light emitting diodes. 1,2 Ohtomo and Hwang 3 have reported on metallicity at the interface between LaAlO 3 and SrTiO 3 , two insulators with sizable band gaps of 5.6 and 3.2 eV, respectively. The creation of metallic states is intimately connected to the structural relaxation. 4 The high mobility of the charge carriers at this interface has initiated many investigations, 5,6 as did the discovery of superconductivity at low temperature. 7 However, despite huge experimental and theoretical efforts, many aspects of the physical picture of the LaAlO 3 /SrTiO 3 (LAO/STO) interface remain open. [8][9][10][11][12][13] To a large extent, this appears to be the result of a complex interplay between structural and electronic reconstructions as well as defects. 14 An essential ingredient of the electronic reconstruction is the transfer of charge between different orbitals, i.e., alterations of the orbital occupations, which can modify the electronic properties of transition metal oxides significantly. 15 An interesting system to disentangle the effects of the charge transfer from other parameters is the KTaO 3 /SrTiO 3 (KTO/STO) heterointerface. KTO has an insulting band gap of 3.75 eV and does not show the ferroelectric phase transition that is common for perovskites. 16,17 The band gap of STO amounts to 3.2 eV. Its electronic, transport, ferroelectric, catalytic, and dielectric properties have been widely studied. [18][19][20][21] Interestingly, the lattice match of KTO with STO is much better than that of LAO with STO. As a consequence, KTO is a promising material for application as an insulator in STO-based field-effect devices. Recently, Kalabukhov et al. 22 have investigated the KTO/STO interface experimentally and found close relations to the LAO/STO interface, even though at the (KO) − (TiO 2 ) 0 contact 0.5 holes per unit cell are transferred, while at the (LaO) + (TiO2) 0 contact 0.5 electrons are transferred.The elect...

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“…It is known that the electronic structure can depend critically on the structural details of the IF. 26 To be save, we consequently have optimized the structure of our system by atomic force minimization. However, due to the minimal lattice mismatch between the component materials, the structure optimization in the present case results only in small modifications of the bond lengths at the IFs.…”

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High charge carrier density at the NaTaO3/SrTiO3 hetero-interface

Nazir

Schwingenschlögl

2011

Applied Physics Letters

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The formation of a (quasi) two-dimensional electron gas between the band insulators NaTaO3 and SrTiO3 is studied by means of the full-potential linearized augmented plane-wave method of density functional theory. Optimization of the atomic positions points to only small changes in the chemical bonding at the interface. Both the p-type (NaO)−/(TiO2)0 and n-type (TaO2)+/(SrO)0 interfaces are found to be metallic with high charge carrier densities. The effects of O vacancies are discussed. Spin-polarized calculations point to the formation of isolated O 2p magnetic moments, located in the metallic region of the p-type interface.

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Interface relaxation and electrostatic charge depletion in the oxide heterostructure LaAlO ₃ /SrTiO ₃

Cited by 51 publications

References 33 publications

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Charge transfer mechanism for the formation of metallic states at the KTaO3/SrTiO3interface

High charge carrier density at the NaTaO3/SrTiO3 hetero-interface

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Interface relaxation and electrostatic charge depletion in the oxide heterostructure LaAlO 3 /SrTiO 3

Cited by 51 publications

References 33 publications

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Charge transfer mechanism for the formation of metallic states at the KTaO3/SrTiO3interface

High charge carrier density at the NaTaO3/SrTiO3 hetero-interface

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Product

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Interface relaxation and electrostatic charge depletion in the oxide heterostructure LaAlO ₃ /SrTiO ₃