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Title: Ground-state oxygen holes and the metal–insulator transition in the negative charge-transfer rare-earth nickelates

The metal-insulator transitions and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. However, a complete understanding of these materials remains elusive. Here, taking a NdNiO 3 thin film as a representative example, we utilize a combination of x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of the rare-earth nickelates. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for the abundance of oxygen 2p holes in the ground state of these materials. Using cluster calculations and Anderson impurity model interpretation, we show that these distinct spectral signatures arise from a Ni 3d 8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a “conventional” positive charge-transfer picture, but instead exhibit a negative charge-transfer energy, in line with recent models interpreting the metal to insulator transition in terms of bond disproportionation.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [4] ;  [3] ;  [6]
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Research Dept. Synchrotron Radiation and Nanotechnology; Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  2. Univ. of Geneva (Switzerland). Dept. of Quantum Matter Physics
  3. Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Physics and Astronomy; Univ. of British Columbia, Vancouver, BC (Canada). Quantum Matter Inst.
  4. Univ. of Geneva (Switzerland). Dept. of Quantum Matter Physics
  5. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Research Dept. Synchrotron Radiation and Nanotechnology; Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed Matter Physics, and Inst. of Physics
  6. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Research Dept. Synchrotron Radiation and Nanotechnology
  7. Univ. of Geneva (Switzerland). Dept. of Quantum Matter Physics; University College London, London (United Kingdom). London Centre for Nanotechnology and Dept. of Physics and Astronomy
  8. Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Physics and Astronomy
Publication Date:
Report Number(s):
BNL-113446-2017-JA
Journal ID: ISSN 2041-1723
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
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; 36 MATERIALS SCIENCE
OSTI Identifier:
1341699