Formation of oxygen vacancies and charge carriers induced in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-type interface of a LaAlO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>overlayer on SrTiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>(001)

Li, Yun; Na-Phattalung, Sutassana; Limpijumnong, Sukit; Kim, Jiyeon; Yu, Jaejun

doi:10.1103/physrevb.84.245307

Cited by 114 publications

(133 citation statements)

References 33 publications

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“…First, V O (S) in the polar film material needs to have a sufficiently low formation energy DH; therefore, it could form in significant quantities. Figure 4a shows that the DH of V O (S) decreases linearly as the film thickness n LAO increases, consistent with previous calculations 20,44 . When n LAO Z3-4 uc, the DH becomes zero or negative, and V O (S) will form spontaneously.…”

Section: Resultssupporting

confidence: 79%

“…This charge transfer in turn cancels the built-in polar field in LaAlO 3 , which caused the low DH of the surface vacancies in the first place. After the built-in field has been cancelled, the DH of V O (S) return to a high value (43 eV) characteristic of the bulk, and V O (S) become again hard to form in thermodynamic equilibrium 20 . Thus, the theoretical maximum concentration of V O (S) is 0.25 S 2D À 1 (where S 2D is 2D unit cell area), that is, one of eight oxygen missing at surface.…”

mentioning

confidence: 99%

“…1) 3,4 . The other three mechanisms involve various defects, including the oxygen vacancies at the interface (denoted as V O (I), where 'I' means 'Interface') [14][15][16] , oxygen vacancies at LaAlO 3 overlayer surface (denoted as V O (S), where S means 'Surface') [17][18][19][20][21][22] , and the La-onSr (La Sr ) antisite donor defects induced by interfacial cation intermixing [23][24][25][26][27][28][29] . As Table 1 shows, each of these proposed mechanisms represents one aspect of the interface physics, explains some experimental findings, but conflicts with a few others 2 .…”

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confidence: 99%

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A polarity-induced defect mechanism for conductivity and magnetism at polar–nonpolar oxide interfaces

2014

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The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO 3 and SrTiO 3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO 3 / SrTiO 3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

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Section: Resultssupporting

confidence: 79%

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confidence: 99%

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confidence: 99%

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A polarity-induced defect mechanism for conductivity and magnetism at polar–nonpolar oxide interfaces

2014

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“…15,[20][21][22] Although the polar discontinuity is still the driving force for the appearance of a conducting layer, the novelty in these approaches is that the mechanism for charge transfer is not a Zener breakdown but the formation, at the critical thickness, of oxygen vacancies on the top surface of LAO (rather than at the interface)-each neutral oxygen vacancy gives two electrons that are transferred to the interface. These models allow us to understand why the top surface is insulating and may also explain why the charge transfer is abrupt at the critical thickness.…”

Section: The Lao/sto System and The Origin Of The Two-dimensional Elementioning

confidence: 99%

Research Update: Conductivity and beyond at the LaAlO3/SrTiO3 interface

2016

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In this review, we focus on the celebrated interface between two band insulators, LaAlO3 and SrTiO3, that was found to be conducting, superconducting, and to display a strong spin-orbit coupling. We discuss the formation of the 2-dimensional electron liquid at this interface, the particular electronic structure linked to the carrier confinement, the transport properties, and the signatures of magnetism. We then highlight distinctive characteristics of the superconducting regime, such as the electric field effect control of the carrier density, the unique tunability observed in this system, and the role of the electronic subband structure. Finally we compare the behavior of Tc versus 2D doping with the dome-like behavior of the 3D bulk superconductivity observed in doped SrTiO3. This comparison reveals surprising differences when the Tc behavior is analyzed in terms of the 3D carrier density for the interface and the bulk.

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“…It is now accepted that the polar field in the LaAlO 3 layer plays a central role in forming the 2DEG at the LaAlO 3 /SrTiO 3 interface. [10][11][12][13] Two recent experimental studies have reported that a 2DEG can be formed solely at a cleaved SrTiO 3 (001) surface. 14,15 It implies that the interface and the polar field are no longer necessary for the creation of 2DEG.…”

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confidence: 99%

Two-dimensional electron gas generated by La-doping at SrTiO3(001) surface: A first-principles study

2013

AIP Advances

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We carried out first-principles calculations to study the electronic properties of SrO-terminated and TiO2-terminated SrTiO3(001) surfaces with La-doping at the surface. We find that an intrinsic lower-lying state at the SrO-terminated surface can accommodate a two-dimensional electron gas (2DEG). By introducing La-doping at the SrO-terminated surface the energy position of the surface state and the 2DEG density can be tuned by changing the doping concentration. The higher the La-doping concentration, the lower the lower-lying state and the higher the 2DEG density. This 2DEG has a small effective mass and hopefully shows a high mobility

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Formation of oxygen vacancies and charge carriers induced in then-type interface of a LaAlO3overlayer on SrTiO3(001)

Cited by 114 publications

References 33 publications

A polarity-induced defect mechanism for conductivity and magnetism at polar–nonpolar oxide interfaces

A polarity-induced defect mechanism for conductivity and magnetism at polar–nonpolar oxide interfaces

Research Update: Conductivity and beyond at the LaAlO3/SrTiO3 interface

Two-dimensional electron gas generated by La-doping at SrTiO3(001) surface: A first-principles study

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