Abstract
We have investigated the temperature ()-dependent evolution of orbital states in a typical spin-orbital-lattice-coupled electron Mott system , based on the electronic structures obtained by the dynamical mean-field theory as well as the density functional theory. We have shown that exhibits the orbital fluctuation feature at high due to degenerate orbitals. Upon cooling, the orbital fluctuation is suppressed by the Jahn-Teller-type crystal field that becomes stronger with the lowering of structural symmetry, and then the ferro-orbital (FO) ordering emerges at low . This FO ordering feature distinguishes from and in that the latter two seem to have antiferro-orbital orderings at low , indicating that the underlying physics is different between them. We propose that the suppression of the orbital fluctuation in can be observed by thermal-conductivity measurement, as observed in spin-orbital-lattice-coupled transition-metal oxides such as .
- Received 28 December 2013
DOI:https://doi.org/10.1103/PhysRevB.89.121106
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