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Site-selective Mott transition in rare-earth-element nickelates
Hyowon Park1, Andrew J Millis, Chris A Marianetti
1Department of Physics, Columbia University, New York, New York 10027, USA.
Physical Review Letters
|October 30, 2012
Summary
A new study reveals that the metal-insulator transition in rare-earth nickelates stems from a site-selective Mott phase. This phase explains localized electrons on some nickel ions and singlet formation with oxygen on others.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Chemistry
Background:
- Rare-earth nickelate perovskites exhibit a notable metal-insulator transition.
- Understanding the electronic behavior of correlated materials is crucial.
Purpose of the Study:
- To elucidate the mechanism behind the metal-insulator transition in rare-earth nickelate perovskites.
- To investigate the role of electron localization and interactions.
Main Methods:
- Employed a combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) calculations.
- Analyzed electron behavior at the atomic level within the nickelate structure.
Main Results:
- Identified a site-selective Mott phase as the origin of the transition.
- Observed localized d electrons on half of the Ni ions, forming fluctuating moments.
- Found d electrons on other Ni ions forming singlets with oxygen holes.
- Replicated key experimental features: insulating gap, varied magnetic moments, and no charge order.
Conclusions:
- The site-selective Mott phase provides a comprehensive explanation for the metal-insulator transition in these materials.
- A link between crystal structure and insulating properties was established.
- The site-selective Mott transition concept may apply to a wider range of correlated materials.
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