Electronic structure of (LaNiO<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>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>/(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>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display

Rüegg, Andreas; Mitra, Chandrima; Demkov, Alexander A.; Fiete, Gregory A.

doi:10.1103/physrevb.85.245131

Cited by 77 publications

(147 citation statements)

References 55 publications

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“…[70][71][72][73][74][75][76][77][78][79][80][81] This and the fact that the CIs and the IQHE liquids belong to the same unitary symmetry class motivated us to focus ex-clusively on CIs in this study. For the spin-up sector of the Kane-Mele (KM) model 37 with strong disorder, we were able to converge (i.e.…”

Section: Introductionmentioning

confidence: 99%

Quantum criticality at the Chern-to-normal insulator transition

Xue

Prodan

2013

Phys. Rev. B

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Using the non-commutative Kubo formula for aperiodic solids and a recently developed numerical implementation, we study the conductivity σ and resistivity ρ tensors as functions of Fermi level E F and temperature T, for models of strongly disordered Chern insulators. The formalism enabled us to converge the transport coefficients at temperatures low enough to enter the quantum critical regime at the Chern-to-trivial insulator transition. We find that the ρ xx -curves at different temperatures intersect each other at one single critical point, and that they obey a single-parameter scaling law with an exponent close to the universally accepted value for the unitary symmetry class. However, when compared with the established experimental facts on the plateau-insulator transition in the Integer Quantum Hall Effect, we find a universal critical conductance σ c xx twice as large, an ellipse rather than a semi-circle law, and absence of the Quantized Hall Insulator phase.

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Section: Introductionmentioning

confidence: 99%

Quantum criticality at the Chern-to-normal insulator transition

Xue

Prodan

2013

Phys. Rev. B

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“…Dirac half-semimetal phase, quantum anomalous Hall insulator phase or ferromagnetic nematic phase) modulated by the strength of electron-electron correlations. [11][12][13][14] CaTiO 3 on LAO, the epitaxial stabilization is possible only if a "screening" buffer layer is grown first on the polar surface. 18 On the other hand, the polarity matching at the interface can have strong influence on the epitaxial growth, defects formation and overall stoichiometry of the layers as observed by the marked interfacial electronic reconstruction for polar LNO film grown on the top of charge neutral STO vs. polar LAO (001) surface.…”

mentioning

confidence: 99%

Epitaxial growth of (111)-oriented LaAlO3/LaNiO3 ultra-thin superlattices

Middey

Meyers

Kareev

et al. 2012

Applied Physics Letters

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The epitaxial stabilization of a single layer or superlattice structures composed of complex oxide materials on polar (111) surfaces is severely burdened by reconstructions at the interface, that commonly arise to neutralize the polarity. We report on the synthesis of high quality LaNiO 3 /mLaAlO 3 pseudo cubic (111) superlattices on polar (111)-oriented LaAlO 3 , the proposed complex oxide candidate for a topological insulating behavior. Comprehensive X-Ray diffraction measurements, RHEED, and element specific resonant X-ray absorption spectroscopy affirm their high structural and chemical quality. The study offers an opportunity to fabricate interesting interface and topology controlled (111) oriented superlattices based on ortho-nickelates.Over the past few years, complex oxide superlattices (SL) with correlated carriers have been widely studied owing to the range of exciting phenomena emerging at the interface which are unattainable in the bulk constituents. 1,2 Recently, active experimental investigations 3-7 on the class of SLs consisting of paramagnetic metal LaNiO 3 (LNO) and LaAlO 3 (LAO) were initiated after the prediction of a possible high T c superconductivity in the LaNiO 3 /LaM O 3 heterostructures (where LaM O 3 is a wide band-gap insulator). 8,9 The experimental realization of LNO/LAO SLs grown on a (001) 10 surface of SrTiO 3 (STO), however, revealed the presence of an unexpected transition to Mott insulating ground state with antiferromagnetic order due to quantum confinement and the effect of d-orbital polarization by the interface. 4,6 Inspired by this approach, several recent theory proposals have been put forward regarding the physics which may emerge in a bilayer of LaNiO 3 sandwiched between LaAlO 3 layers grown along the [111] crystallographic direction. Specifically, the theory predicts the appearance of exotic topological phases (e.g. Dirac half-semimetal phase, quantum anomalous Hall insulator phase or ferromagnetic nematic phase) modulated by the strength of electron-electron correlations. CaTiO 3 on LAO, the epitaxial stabilization is possible only if a "screening" buffer layer is grown first on the polar surface. 18 On the other hand, the polarity matching at the interface can have strong influence on the epitaxial growth, defects formation and overall stoichiometry of the layers as observed by the marked interfacial electronic reconstruction for polar LNO film grown on the top of charge neutral STO vs. polar LAO (001) surface. 19 In this letter, we present the results of artificial layerby-layer growth of an unique class of (111)-oriented 2LNO/mLAO heterostructures (with m = 2, 3, and 4 unit cells) on LAO (111) single crystal (see Fig. 1(a)). The LAO substrate was selected to eliminate the effects of lattice mismatch (i.e. strain) between the layers, which otherwise may hinder the quality of growth. The extensive characterization using reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray diffraction (XRD), and synchrotron based resonant X-ray ...

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“…For example, chromium-doped Bi 2 Te 3 exhibits an FM order with Curie temperature T C ≈ 15 K, while manganese-dope HgTe is paramagnetic [15] in experiment. In addition, QAH states have also been predicted to exist in transition metal oxide heterostructures [16][17][18][19][20][21], graphene [22][23][24], silicene [25][26][27], magnetic thin layers containing heavy elements [28], and magnetic topological crystalline insulators [29,30].…”

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confidence: 99%

Prediction of Near-Room-Temperature Quantum Anomalous Hall Effect on Honeycomb Materials

2014

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Recently, this long-sought quantum anomalous Hall effect was realized in the magnetic topological insulator. However, the requirement of an extremely low temperature (approximately 30 mK) hinders realistic applications. Based on ab-initio band structure calculations, we propose a quantum anomalous Hall platform with a large energy gap of 0.34 and 0.06 eV on honeycomb lattices comprised of Sn and Ge, respectively. The ferromagnetic order forms in one sublattice of the honeycomb structure by controlling the surface functionalization rather than dilute magnetic doping, which is expected to be visualized by spin polarized STM in experiment. Strong coupling between the inherent quantum spin Hall state and ferromagnetism results in considerable exchange splitting and consequently an ferromagnetic insulator with a large energy gap. The estimated mean-field Curie temperature is 243 and 509 K for Sn and Ge lattices, respectively. The large energy gap and high Curie temperature indicate the feasibility of the quantum anomalous Hall effect in the near-room-temperature and even room-temperature regions.PACS numbers: 71.70. Ej,73.43.Cd, The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase characterized by a finite Chern number and chiral edge states inside the bulk band gap, which leads to the quantized Hall effect without a magnetic field [1]. The chiral edge states carry dissipationless electric current owing to robustness against backscattering [2] and are therefore attractive for applications in low-power-consumption electronics. Recently, this long-sought QAH effect was realized chromium-doped (Bi,Sb) 2 Te 3 (ref.[3]), the magnetic topological insulator [4,5]. However, the requirement of an extremely low temperature (approximately 30 mK) hinders realistic applications, which is fundamentally limited by the bulk energy-gap and the ferromagnetic Curie temperature [3]. Thus, novel materials are in high demand for future applications of the QAH effect.In a quantum spin Hall (QSH) system [6][7][8], the topological band structure is identified by a band inversion in both spin channels that are time-reversal (TR) conjugates of each other. A pair of counter-propagating edge states with opposite spins exists, i.e., two copies of quantum anomalous Hall (QAH) edge states. If the ferromagnetic (FM) order suppresses one of the spin channels, it can lead to the QAH effect [9][10][11]. The band inversion in a single spin channel, which is characterized by a finite Chern number, originates from the gapless edge state inside the bulk energy-gap. Therefore, the following transition-metal-doped topological insulators were proposed to realize the QAH effects: the aforementioned chromium-doped Bi 2 Te 3 (ref.[11]), manganesedoped HgTe quantum wells (QWs) [10,12], and other magnetically doped QWs [13,14]. The bulk energy-gap of these 2D QSH insulators are usually of the order of 1 or 10 meV. It is believed that the ferromagnetism of a magnetic QSH insulator can be enhanced owing to the band edge singularity of such an ...

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Electronic structure of (LaNiO3)2/(LaAlO3)

Cited by 77 publications

References 55 publications

Quantum criticality at the Chern-to-normal insulator transition

Quantum criticality at the Chern-to-normal insulator transition

Epitaxial growth of (111)-oriented LaAlO3/LaNiO3 ultra-thin superlattices

Prediction of Near-Room-Temperature Quantum Anomalous Hall Effect on Honeycomb Materials

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