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Title: Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover

Abstract

In situ photoemission spectroscopy and x-ray absorption spectroscopy (XAS) have been performed on LaNiO3 (LNO) ultrathin films grown on LaAlO3 substrates to investigate the origin of the thickness-dependent metalinsulator transition (MIT). With decreasing film thickness, the progressive weakening of a quasiparticle peak at the Fermi level (EF ) occurs below 10 monolayer (ML), and the further depletion of spectral weight at EF leads to pseudogap behavior at 3 6 ML. The pseudogap finally evolves into a full gap, indicating that the thickness-dependent MIT takes place at a critical film thickness of 2 3 ML. The observed spectral behavior is in line with the transport properties of LNO ultrathin films. The thickness dependence of the spectral intensity is compared with realistic multiorbital dynamical mean-field theory. The experimental spectral function was found to depend on the film thickness more strongly than the theoretical one for thinner systems, indicating that the thickness-dependent MIT in LNO is caused by the crossover from three to two dimensions, during which the spatial correlations are progressively enhanced. The XAS results suggest that a charge disproportionate state is strongly suppressed in LNO ultrathin films plausibly as a result of epitaxial strain from the substrates. These results strongly suggestmore » that a novel insulating state is realized in LNO films at a thin limit.« less

Authors:
 [1];  [1];  [1];  [2];  [1];  [1];  [1]
  1. University of Tokyo, Tokyo, Japan
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1063819
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 87; Journal Issue: 7; Journal ID: ISSN 1098--0121
Country of Publication:
United States
Language:
English
Subject:
oxide thin films; strongly correlated electron systems; metal-insulator transition

Citation Formats

Sakai, E., Tamamitsu, M., Yoshimatsu, K, Okamoto, Satoshi, Horiba, K., Oshima, M, and Kumigashira, H. Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover. United States: N. p., 2013. Web. doi:10.1103/PhysRevB.87.075132.
Sakai, E., Tamamitsu, M., Yoshimatsu, K, Okamoto, Satoshi, Horiba, K., Oshima, M, & Kumigashira, H. Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover. United States. https://doi.org/10.1103/PhysRevB.87.075132
Sakai, E., Tamamitsu, M., Yoshimatsu, K, Okamoto, Satoshi, Horiba, K., Oshima, M, and Kumigashira, H. Tue . "Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover". United States. https://doi.org/10.1103/PhysRevB.87.075132.
@article{osti_1063819,
title = {Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover},
author = {Sakai, E. and Tamamitsu, M. and Yoshimatsu, K and Okamoto, Satoshi and Horiba, K. and Oshima, M and Kumigashira, H},
abstractNote = {In situ photoemission spectroscopy and x-ray absorption spectroscopy (XAS) have been performed on LaNiO3 (LNO) ultrathin films grown on LaAlO3 substrates to investigate the origin of the thickness-dependent metalinsulator transition (MIT). With decreasing film thickness, the progressive weakening of a quasiparticle peak at the Fermi level (EF ) occurs below 10 monolayer (ML), and the further depletion of spectral weight at EF leads to pseudogap behavior at 3 6 ML. The pseudogap finally evolves into a full gap, indicating that the thickness-dependent MIT takes place at a critical film thickness of 2 3 ML. The observed spectral behavior is in line with the transport properties of LNO ultrathin films. The thickness dependence of the spectral intensity is compared with realistic multiorbital dynamical mean-field theory. The experimental spectral function was found to depend on the film thickness more strongly than the theoretical one for thinner systems, indicating that the thickness-dependent MIT in LNO is caused by the crossover from three to two dimensions, during which the spatial correlations are progressively enhanced. The XAS results suggest that a charge disproportionate state is strongly suppressed in LNO ultrathin films plausibly as a result of epitaxial strain from the substrates. These results strongly suggest that a novel insulating state is realized in LNO films at a thin limit.},
doi = {10.1103/PhysRevB.87.075132},
url = {https://www.osti.gov/biblio/1063819}, journal = {Physical Review B},
issn = {1098--0121},
number = 7,
volume = 87,
place = {United States},
year = {2013},
month = {1}
}