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Title: Influence of quantum confinement and strain on orbital polarization of four-layer LaNiO3 superlattices: A DFT+DMFT study

Atomically precise superlattices involving transition metal oxides provide a unique opportunity to engineer correlated electron physics using strain (modulated by choice of substate) and quantum confinement (controlled by layer thickness). We use the combination of density functional theory and dynamical mean field theory (DFT+DMFT) to study Ni Eg d-orbital polarization in strained LaNiO3/LaAlO3 superlattices consisting of four layers of nominally metallic NiO2 and four layers of insulating AlO2 separated by LaO layers. The layer-resolved orbital polarization is calculated as a function of strain and analyzed in terms of structural, quantum confinement, and correlation effects. We determined that the effect of strain is from the dependence of the results on the Ni-O bondlength ratio and the octahedral rotation angles; quantum confinement is studied by comparison to bulk calculations with similar degrees of strain; correlation effects are inferred by varying interaction parameters within our DFT+DMFT calculations. The calculated dependence of orbital polarization on strain in superlattices is qualitatively consistent with recent X-ray absorption spectroscopy and resonant reflectometry data. But, interesting differences of detail are found between theory and experiment. Under tensile strain, the two inequivalent Ni ions display orbital polarization similar to that calculated for strained bulk LaNiO3 and observed in experiment.more » Compressive strain produces a larger dependence of orbital polarization on Ni position and even the inner Ni layer exhibits orbital polarization different from that calculated for strained bulk LaNiO3.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Univ. of Illinois, Chicago, IL (United States). Dept. of Physics; Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  2. Columbia Univ., New York, NY (United States). Dept. of Physics
  3. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
Publication Date:
OSTI Identifier:
1352657
Grant/Contract Number:
AC02-06CH11357; FG02-04ER46169
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 93; Journal Issue: 23; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Laboratory (ANL)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY