Ground state valency and spin configuration of the Ni ions in nickelates

The ab initio self-interaction-corrected local-spin-density approximation is used to study the electronic structure of both stoichiometric and nonstoichiometric nickelates. From total energy considerations it emerges that, in their ground state, both LiNiO2 and NaNiO2 are insulators, with the Ni ion...

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Bibliographic Details
Published in:Physical review letters 2006-10, Vol.97 (14), p.146405-146405, Article 146405
Main Authors: Petit, L, Stocks, G M, Egami, T, Szotek, Z, Temmerman, W M
Format: Article
Language:English
Subjects:
APPROXIMATIONS
ATOMS
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
CONFIGURATION
DISTRIBUTION
ELECTRONIC STRUCTURE
GROUND STATES
IMPURITIES
NICKELATES
SPIN
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Summary:The ab initio self-interaction-corrected local-spin-density approximation is used to study the electronic structure of both stoichiometric and nonstoichiometric nickelates. From total energy considerations it emerges that, in their ground state, both LiNiO2 and NaNiO2 are insulators, with the Ni ion in the Ni3+ low-spin state (t(2g)(6)e(g)(1)) configuration. It is established that a substitution of a number of Li/Na atoms by divalent impurities drives an equivalent number of Ni ions in the NiO2 layers from the Jahn-Teller (JT)-active trivalent low-spin state to the JT-inactive divalent state. We describe how the observed considerable differences between LiNiO2 and NaNiO2 can be explained through the creation of Ni2+ impurities in LiNiO2. The indications are that the random distribution of the Ni2+ impurities might be responsible for the destruction of the long-range orbital ordering in LiNiO2.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.97.146405