Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>LaAlO</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>Heterostructures: A Resonant Soft-X-Ray Scattering Study

Park, Jihye; Cho, B.-G.; Kim, K. D.; Koo, Jin Young; Jang, Hyun M.; Ko, Kyung-Tae; Park, Jae Hoon; Lee, Kibong; Kim, J.-Y.; Lee, D.R.; Burns, C. A.; Seo, S. S. A.; Lee, Ho Nyung

doi:10.1103/physrevlett.110.017401

Cited by 44 publications

(18 citation statements)

References 31 publications

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“…O deficiency in the BiO layer also results in an energetical downshift of all states, but additionally the d z r 3 2 2orbitals become partially occupied. In principle, orbital reconstructions similar to those dominating the properties of the O deficient LaAlO 3 /SrTiO 3 interface [34] can be expected to appear also in our case. However, figure 5 demonstrates that the spin polarization of the Ti atoms at the interface is mostly carried by the d z r 3 2 2states, whereas at the LaMnO 3 /SrTiO 3 interface the induced Ti magnetic moments are always due to the d xy states [32,33].…”

Section: Resultssupporting

confidence: 60%

Role of O defects at the BiMnO₃/SrTiO₃interface

2016

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We use first principles calculations to study ideal and O deficient BiMnO 3 /SrTiO 3 superlattices. The ideal superlattice is characterized by parallel alignment of the Mn and Ti magnetic moments at the n-interface, while an antiparallel alignment has been reported experimentally. O defects at the n-interface are found to favor the MnO 2 and BiO layers over the TiO 2 layer. The band gap of the superlattice is strongly reduced when the MnO 2 layer is O deficient and d z r 3 2 2states are observed at the Fermi energy when the BiO layer is O deficient. Only in the latter case the Mn and Ti magnetic moments at the n-interface align antiparallel. Therefore, O defects in the BiO layer turn out to be essential for reproducing the experimental interface magnetism and for understanding its mechanism.

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Section: Resultssupporting

confidence: 60%

Role of O defects at the BiMnO₃/SrTiO₃interface

2016

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“…Additional issues beyond conceptual approaches to interface control arise. The length scales in correlated oxides are typically very short, so the details of the interface may be more important than in conventional semiconductors.A local picture is needed, which is able to address the formation of chemical bonds across the junction, differing elec-tronegativities of transition metal ions, changes in both crystal field energies and Madelung potentials, and polarity effects (Biscaras et al, 2012;Garcia-Barriocanal et al, 2013;Herranz et al, 2007;Hotta et al, 2007;Ohtomo and Hwang, 2004;Park et al, 2013b;Salluzzo et al, 2013;Savoia et al, 2009;Sing et al, 2009;Takizawa et al, 2009;Zhong et al, 2010).…”

Section: B Additional Considerationsmentioning

confidence: 99%

Colloquium: Emergent properties in plane view: Strong correlations at oxide interfaces

et al. 2014

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“…However, depending on the vacancy distribution, both Kondo and FM domains in principle can occur at the STO/polar material interfaces. Finally, we comment on the x-ray absorption spectroscopy of STO/LAO interface [67,68]. The experiments show OVs are crucial to the existence of magnetic impurities, consistent with that OVs are magnetic impurities.…”

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confidence: 98%

“…Before being specific, we notice that in almost all literature [10,17,18,67,68], the magnetic impurities near the interface are claimed to be Ti 3+ . Our analysis suggests that an OV can provide an alternative explanation.…”

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Consequences of Oxygen-Vacancy Correlations at theSrTiO3Interface

Lin

Demkov

2014

Phys. Rev. Lett.

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The Kondo effect and ferromagnetism are the two many-body phenomena that emerge at the SrTiO3 interfaces with polar materials, but do not occur in bulk SrTiO3. By regarding the oxygen vacancy (OV) in SrTiO3 as a magnetic impurity, we show that these two interface specific phenomena can be attributed to the vacancies residing in the top TiO2 plane of SrTiO3. We identify three crucial ingredients the local orbital mixing caused by an OV, reduced symmetry at the interface, and strong in-plane stray electric field of the polar material. All three factors combine to result in the coupling between the impurity and conduction band at the interface, and can lead to both emergent phenomena. An OV-based Anderson impurity model is derived and solved using the numerical renormalization group method. The Kondo and Curie temperatures are estimated. Several experiments based on this interpretation are discussed.PACS numbers: 79.60. Dp, 71.27.+a Perovskite SrTiO 3 (STO) is a non-magnetic band insulator with a band gap of 3.2 eV [1, 2]. Its versatile response to different dopants makes STO an ideal host for building functional materials and has drawn significant attention.For example, an insulating ferromagnetic (FM) order at room temperature is observed in STO when replacing some Ti atoms by Co [3,4]. The band gap of STO can be engineered by Al doping [5]. When a small number of conduction electrons are introduced, even more fascinating phenomena such as superconductivity [6][7][8], long-lived magnetic moments [9], metallic ferromagnetism or super-paramagnetism (SPM, several separate macroscopic FM domains) [10][11][12][13][14][15], Kondo resistance minimum [16][17][18], and two-dimensional electron gas [19][20][21][22] emerge. Among these emergent phenomena, the ferromagnetism and Kondo effect are special in that they, unlike the superconductivity, only occur at the STO/LaAlO 3 (LAO) (for FM) [10][11][12][13]23], and STO/ionic liquid interfaces (for Kondo effect) [17,18, 24], but do not occur in the n-doped bulk STO [25][26][27][28][29][30]. In this letter, we investigate the role of oxygen vacancies (OV) in these two phenomena. We find the OV, residing in the top TiO 2 plane, plays an important role in distinguishing the interface behavior from the bulk. By regarding OVs in STO as magnetic impurities [31], we identify three crucial ingredients necessary for FM and Kondo effect to occur -(i) local orbital mixing at the adjacent Ti sites caused by an OV, (ii) symmetry reduction near the interface, and (iii) strong in-plane stray electric field induced by the polar interface. A combination of these three factors results in an impurity-conduction band coupling near the interface and can lead to the emergent FM phase and Kondo effect.We begin by summarizing the key features of an OV in STO from the density functional theory (DFT) [32][33][34][35][36][37][38].The conduction bands of bulk STO are mainly derived from Ti 3d orbitals, with triple-degenerate t 2g bands about 2.5 eV below the double-degenerate e g bands in energy. Whe...

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Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface ofLaAlO3/SrTiO3Heterostructures: A Resonant Soft-X-Ray Scattering Study

Cited by 44 publications

References 31 publications

Role of O defects at the BiMnO₃/SrTiO₃interface

Role of O defects at the BiMnO₃/SrTiO₃interface

Colloquium: Emergent properties in plane view: Strong correlations at oxide interfaces

Consequences of Oxygen-Vacancy Correlations at theSrTiO3Interface

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Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface ofLaAlO3/SrTiO3Heterostructures: A Resonant Soft-X-Ray Scattering Study

Cited by 44 publications

References 31 publications

Role of O defects at the BiMnO3/SrTiO3interface

Role of O defects at the BiMnO3/SrTiO3interface

Colloquium: Emergent properties in plane view: Strong correlations at oxide interfaces

Consequences of Oxygen-Vacancy Correlations at theSrTiO3Interface

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Role of O defects at the BiMnO₃/SrTiO₃interface

Role of O defects at the BiMnO₃/SrTiO₃interface