Jahn-Teller effect in systems with strong on-site spin-orbit coupling
Abstract
When strong spin-orbit coupling removes orbital degeneracy, it would at the same time appear to render the Jahn-Teller mechanism ineffective. We discuss such a situation, the t_2g manifold of iridates, and show that, while the Jahn-Teller effect does indeed not affect the j_eff=1/2 antiferromagnetically ordered ground state, it leads to distinctive signatures in the j_eff=3/2 spin-orbit exciton. It allows for a hopping of the spin-orbit exciton between the nearest neighbor sites without producing defects in the j_eff=1/2 antiferromagnet. This arises because the lattice-driven Jahn-Teller mechanism only couples to the orbital degree of freedom, but is not sensitive to the phase of the wave function that defines isospin j_z. This contrasts sharply with purely electronic propagation, which conserves isospin, and presence of Jahn-Teller coupling can explain some of the peculiar features of measured resonant inelastic x-ray scattering spectra of Sr_2IrO_4.
Cite
@article{arxiv.1601.07069,
title = {Jahn-Teller effect in systems with strong on-site spin-orbit coupling},
author = {Ekaterina M. Plotnikova and Maria Daghofer and Jeroen van den Brink and Krzysztof Wohlfeld},
journal= {arXiv preprint arXiv:1601.07069},
year = {2016}
}
Comments
9 pages, 6 figures including the supplementary material