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Damped orbital excitations in the titanates

K. Kikoin·O. Entin-Wohlman·V. Fleurov·A. Aharony
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Abstract

A possible mechanism for the removal of the orbital degeneracy in RTiO3 (where R=La, Y, ...) is considered. The calculation is based on the Kugel-Khomskii Hamiltonian for electrons residing in the t2g orbitals of the Ti ions, and uses a self-consistent pe rturbation expansion in the interaction between the orbital and the spin degrees of freedom. The latter are assumed to be ordered in a Neel state, brought about by delicate interactions that are not included in the Kugel-Khomskii Hamiltonian. Within our model calculations, each of the t2g bands is found to acquire a finite, temperature-dependent dispersion, that lifts the orbital degeneracy. The orbital excitations are found to be heavily damped over a rather wide band. Consequently, they do not participate as a separate branch of excitations in the low-temperature thermodynamics.e

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K. Kikoin, O. Entin-Wohlman, V. Fleurov, A. Aharony. 2003-02-10. Damped orbital excitations in the titanates. https://doi.org/10.1103/physrevb.67.214418

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