Orbital reflectometry of oxide heterostructures

Benckiser, E.; Haverkort, M. W.; Brück, S.; Goering, E.; Macke, S.; Frañó, Alex; Yang, Xiaoping; Andersen, O. K.; Cristiani, G.; Habermeier, H.–U.; Boris, A. V.; Zegkinoglou, Ioannis; Wochner, P.; Kim, Heon‐Jung; Hinkov, V.; Keimer, B.

doi:10.1038/nmat2958

Cited by 234 publications

(282 citation statements)

References 34 publications

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“…From the single-site DMFT calculations with a double-counting energy as another tuning parameter, Wang et al 21 showed that there is a well defined N c , that is, the critical value of d-valency of transition metal; the system is metallic if Relative orbital occupation in the two e g orbitals is a central quantity in understanding LNO/LAO systems 9,12,14,15 . The orbital polarization can be nonzero due to the translation symmetry breaking induced by heterostructuring while the bulk polarization is 0.…”

Section: Resultsmentioning

confidence: 99%

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Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
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Density functional band calculations have been performed to study LaNiO3/LaAlO3 superlattices. Motivated by recent experiments reporting the magnetic and metal-insulator phase transition as a function of LaNiO3 layer thickness, we examined the electronic structure, magnetic properties, and orbital occupation depending on the number of LaNiO3 layers. Calculations show that the magnetic phase is stabler than the nonmagnetic for finite and positive U values. The orbital polarization is significantly reduced by U even in the magnetic regions. The implications of the results are discussed in comparison to recent experimental and theoretical studies within the limitations of the LDA+U method.PACS numbers: 71.15.Mb

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Section: Resultsmentioning

confidence: 99%

“…One of the most intriguing classes of materials may be the nickelate superlattices [9][10][11][12][13][14][15][16] . A series of recent theoretical studies have created considerable interest, suggesting the heterostructuring-induced orbital polarization and the possible high-T c superconductivity in LaNiO 3 (LAO)/LaAlO 3 (LAO) superlattice 12,17 .…”

mentioning

confidence: 99%

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
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“…11b, 20 There is no shift in the polarization-averaged edge, indicating stoichiometric Ni 3+ with an insignificant amount of oxygen defects in our LNO films ( Supplementary Fig. S9).…”

mentioning

confidence: 82%

Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO₃ Perovskites

Petrie¹,

Cooper²,

et al. 2016

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ABSTRACT:Strain is known to greatly influence low temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. However, its catalytic impact on transition metal oxide (TMO) thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO 3 to systematically determine its influence on both the oxygen reduction (ORR) and oxygen evolution reaction (OER). Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to straininduced splitting of the e g orbitals, which can customize orbital asymmetry at the surface. Analogous to straininduced shifts in the d-band center of noble metals relative to Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides. Advancements in energy storage are essential for driving the development of more sophisticated mobile technologies as well as continuing the trend towards a greener economy. At the forefront of this push are high energy density devices, such as regenerative fuel cells and metal-air batteries. 1 In these and related electrochemical systems, both the oxygen reduction and oxygen evolution reactions (ORR and OER, respectively) are crucial towards successful operation. 2 Traditionally, conductive catalysts incorporating noble metals (e.g., Pt and IrO 2 ) have been used to facilitate these reactions near room temperature. 3 To alleviate costs and poor stabilities during OER in alkaline solutions, significant efforts have focused on transition metal oxides (TMOs) with multivalent Ni, Fe, Co, and Mn, such as NiFeO x .4 Similar to alloying in noble metals, the majority of research into increasing oxygen activities of TMOs involves cationic doping, which often promotes either the ORR or OER but not bifunctionality. 5Here, we explore how another factor, i.e. strain, can influence bifunctionality in TMOs. Contemporary work on high-temperature (>500 C) oxide catalysis in an aprotic environment (e.g. ORR: O 2 + 4e -→ 2O 2-) has emphasized the importance of tensile strain for activating defects to improve catalytic reactions. 6 In an alkaline environment (e. . Among TMOs, the ABO 3 perovskites, in which A is traditionally from Groups I-III and B is a transition metal ion with six-fold octahedral coordination, also have electronic structures that are sensitive to strain. Due to strong hybridization between the O 2p and the transition metal d z 2 and d x 2 -y 2 lobes in the BO 6 octahedra, the σ* states near E F consist of e g orbitals. 10,10b Similar to the Jahn-Teller distortion, strain is known to lift the degeneracy in these symmetry-localized d z 2 and d x 2 -y 2 orbitals, yielding changes in the orbital occupancy, or polarization.7a, 11 By using strain to control the degree of this ...

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“…1,2 This degree of freedom creates a rich variety of behaviors, and a large area in materials science and technology focuses on understanding and controlling these properties (e.g. magnetism, superconductivity, ferroelectricity, etc.)…”

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confidence: 99%

“…This difference should be detectable by x-ray linear dichroism (XLD) 9,10 or orbital reflectometry. 2 Second, we have explicitly computed and compared tetragonal to that of the BaTiO 3 /LSMO interface, but is quantitatively larger than the orbital polarization of the BaTiO 3 /LSMO interface due to the larger ferroelectric polarization of PbTiO 3 .…”

mentioning

confidence: 99%

Reversible Modulation of Orbital Occupations via an Interface-Induced Polar State in Metallic Manganites

Chen¹,

Qiao

Marshall³

et al. 2014

Nano Lett.

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Orbital reflectometry of oxide heterostructures

Abstract: arXiv:1101.0238v1 [cond-mat.str-el]

Cited by 234 publications

References 34 publications

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
View full text Add to dashboard Cite

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
View full text Add to dashboard Cite

Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO₃ Perovskites

Reversible Modulation of Orbital Occupations via an Interface-Induced Polar State in Metallic Manganites

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Orbital reflectometry of oxide heterostructures

Abstract: arXiv:1101.0238v1 [cond-mat.str-el]

Cited by 234 publications

References 34 publications

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+UHan1, Veenendaal2 2012Phys. Rev. B224182View full textAdd to dashboardCite

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+UHan1, Veenendaal2 2012Phys. Rev. B224182View full textAdd to dashboardCite

Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

Reversible Modulation of Orbital Occupations via an Interface-Induced Polar State in Metallic Manganites

Contact Info

Product

Resources

About

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
View full text Add to dashboard Cite

Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U
Han
¹
,
Veenendaal
²

2012
Phys. Rev. B
22
4
18
2
View full text Add to dashboard Cite

Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO₃ Perovskites