We present an analytical calculation of the spin-wave spectrum of the Jahn-Teller system LaTiO3. The calculation includes all superexchange couplings between nearest-neighbor Ti ions allowed by the space-group symmetries: The isotropic Heisenberg couplings and the antisymmetric (Dzyaloshinskii-Moriya) and symmetric anisotropies. The calculated spin-wave dispersion has four branches, two nearly degenerate branches with small zone-center gaps and two practically indistinguishable high-energy branches having large zone-center gaps. The two lower-energy modes are found to be in satisfying agreement with neutron-scattering experiments. In particular, the experimentally detected approximate isotropy in the Brillouin zone and the small zone-center gap are well reproduced by the calculations. The higher-energy branches have not been detected yet by neutron scattering but their zone-center gaps are in satisfying agreement with recent Raman data.
@article{arxiv.cond-mat/0411583,
title = {The spin-wave spectrum of the Jahn-Teller system LaTiO3},
author = {Robert Schmitz and Ora Entin-Wohlman and Amnon Aharony and A. Brooks Harris and Erwin Mueller-Hartmann},
journal= {arXiv preprint arXiv:cond-mat/0411583},
year = {2009}
}