Modifying the Electronic Orbitals of Nickelate Heterostructures via Structural Distortions

Chen, Hanghui; Kumah, Divine P.; Disa, Ankit; Walker, Frederick J.; Ahn, Charles; Ismail‐Beigi, Sohrab

doi:10.1103/physrevlett.110.186402

Cited by 74 publications

(91 citation statements)

References 47 publications

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“…The key question is whether conditions can be found such that this OP is large and the quasi two-dimensional d x 2 −y 2 band is a dominantly occupied one with proper filling. This issue was previously investigated by Hansmann et al 21,22 and Han et al, 23 for LaNiO 3 /LaAlO 3 heterostructures, and proposals for achieving high OP by using other LNObased heterostructures [24][25][26][27] or chemical control by other counterions 28,29 were made.…”

Section: Introductionmentioning

confidence: 99%

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

2014

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Transition-metal heterostructures offer the fascinating possibility of controlling orbital degrees of freedom via strain. Here, we investigate theoretically the degree of orbital polarization that can be induced by epitaxial strain in LaNiO3 films. Using combined electronic structure and dynamical mean-field theory methods we take into account both structural distortions and electron correlations and discuss their relative influence. We confirm that Hund's rule coupling tends to decrease the polarization and point out that this applies to both the d 8 L and d 7 local configurations of the Ni ions. Our calculations are in good agreement with recent experiments, which revealed sizable orbital polarization under tensile strain. We discuss why full orbital polarization is hard to achieve in this specific system and emphasize the general limitations that must be overcome to achieve this goal.

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Section: Introductionmentioning

confidence: 99%

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

2014

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“…14,15 The principle is based on the transfer of a single electron from the LTO layer (Ti 3+ ) to the LNO layer (Ni 3+ ) due to the mismatch in electronegativity of the two ions. The electron transfer creates a charge imbalance and, hence, a dipole field which leads to large polar distortions with polarization pointing towards the NiO 2 layer of the LNO.…”

Section: Introductionmentioning

confidence: 99%

Experimental verification of orbital engineering at the atomic scale: Charge transfer and symmetry breaking in nickelate heterostructures

et al. 2017

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Epitaxial strain, layer confinement and inversion symmetry breaking have emerged as powerful new approaches to control the electronic and atomic-scale structural properties in complex metal oxides. Nickelate heterostructures, based on RENiO 3 , where RE is a trivalent rare-earth cation, have been shown to be relevant model systems since the orbital occupancy, degeneracy, and, consequently, the electronic/magnetic properties can be altered as a function of epitaxial strain, layer thickness and superlattice structure. One such recent example is the tri-component LaTiO 3 -LaNiO 3 -LaAlO 3 superlattice, which exhibits charge transfer and orbital polarization as the result of its interfacial dipole electric field. A crucial step towards control of these parameters for future electronic and magnetic device applications is to develop an understanding of both the magnitude and range of the octahedral networks response towards interfacial strain and electric fields.An approach that provides atomic-scale resolution and sensitivity towards the local octahedral distortions and orbital occupancy is therefore required. Here, we employ atomic-resolution imaging coupled with electron spectroscopies and first principles theory to examine the role of interfacial charge transfer and symmetry breaking in a tricomponent nickelate superlattice system. We find that nearly complete charge transfer occurs between the LaTiO 3 and LaNiO 3 layers, resulting in a Ni 2+ valence state. We further demonstrate that this charge transfer is highly localized with a range of about 1 unit cell, within the LaNiO 3 layers. The results presented here provide important feedback to synthesis efforts aimed at stabilizing new electronic phases that are not accessible by conventional bulk or epitaxial film approaches.PACS numbers:

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“…Chemical doping by hydrogen incorporation into nickelate lattices has been shown to modify the ground state properties by inducing a colossal change in the resistivity that can be reversed by removing the dopant species from the lattice 10 . Nickelates have also been proposed to serve as candidate systems for understanding high temperature superconductivity due to the rich physics inherent in d-orbital non-degeneracy [23][24][25] . These interesting observations opens up a possibility of realizing new electrical and magnetic ground states for the electron doped nickelates.…”

Section: Introductionmentioning

confidence: 99%

Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

et al. 2016

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We present low temperature resistivity and magnetotransport measurements conducted on pristine and electron doped SmNiO3 (SNO). The low temperature transport in both pristine and electrondoped SNO shows a Mott variable range hopping with a substantial decrease in localization length of carriers by one order in the case of doped samples. Un-doped SNO films show a negative magnetoresistance (MR) at all temperatures characterized by spin fluctuations with the evolution of a positive cusp at low temperatures. In striking contrast, upon electron doping of the films via hydrogenation, we observe a crossover to a linear non-saturating positive MR∼ 0.2 % at 50 K . The results signify the role of localization phenomena in tuning the magnetotransport response in doped nickelates. Ionic doping is therefore a promising approach to tune magnetotransport in correlated perovskites.

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Modifying the Electronic Orbitals of Nickelate Heterostructures via Structural Distortions

Cited by 74 publications

References 47 publications

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Experimental verification of orbital engineering at the atomic scale: Charge transfer and symmetry breaking in nickelate heterostructures

Sign reversal of magnetoresistance in a perovskite nickelate by electron doping

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