Spin-orbital order in the undoped manganite LaMnO3 at finite temperature

We investigate the evolution of spin and orbital order in undoped LaMnO3 under increasing temperature with a model including both superexchange and Jahn-Teller interactions. We used several cluster mean field calculation schemes and find coexisting A-type antiferromagnetic and C-type alternating orb...

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Bibliographic Details
Published in:Physical review. B 2016-12, Vol.94 (22), p.214426
Main Authors: Snamina, Mateusz, Oleś, Andrzej M
Format: Article
Language:English
Subjects:
Antiferromagnetism
Correlation analysis
Decoupling
Entanglement
Jahn-Teller effect
Lanthanum compounds
Magnetic properties
Magnetic transitions
Operators
Optical properties
Temperature dependence
Transition temperature
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Summary:We investigate the evolution of spin and orbital order in undoped LaMnO3 under increasing temperature with a model including both superexchange and Jahn-Teller interactions. We used several cluster mean field calculation schemes and find coexisting A-type antiferromagnetic and C-type alternating orbital order at low temperature. The value of the Jahn-Teller coupling between strongly correlated eg orbitals is estimated from the orbital transition temperature at TOO≃780 K. By a careful analysis of onsite and on-bond correlations, we demonstrate that spin-orbital entanglement is rather weak. We have verified that the magnetic transition temperature is influenced by entangled spin-orbital operators as well as by entangled orbital operators on the bonds, but the errors introduced by decoupling such operators partly compensate each other. Altogether, these results justify why the commonly used disentangled spin-orbital model is so successful in describing the magnetic properties and the temperature dependence of the optical spectral weights for LaMnO3.
ISSN:2469-9950
2469-9969