Orbital ordering in frustrated Jahn-Teller systems with 90 degrees exchange.
Phys Rev Lett
; 89(22): 227203, 2002 Nov 25.
Article
en En
| MEDLINE
| ID: mdl-12485100
ABSTRACT
We show that superexchange interactions in frustrated Jahn-Teller systems with transition metal ions connected by the 90 degrees metal-oxygen-metal bonds (e.g., NaNiO2, LiNiO2, and ZnMn2O4) are much different from those in materials with the 180 degrees bonds. In the 90 degrees -exchange systems spins and orbitals are decoupled the spin exchange is much weaker than the orbital one and it is ferromagnetic for all orbital states. Though the mean-field orbital ground state is strongly degenerate, quantum orbital fluctuations select particular ferro-orbital states. We explain the orbital and magnetic ordering observed in NaNiO2 and show that LiNiO2 is not a spin-orbital liquid.
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MEDLINE
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En
Revista:
Phys Rev Lett
Año:
2002
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Article