We study Na2IrO3 by ARPES, optics, and band structure calculations in the local-density approximation (LDA). The weak dispersion of the Ir 5d-t2g manifold highlights the importance of structural distortions and spin-orbit coupling (SO) in driving the system closer to a Mott transition. We detect an insulating gap {\Delta}_gap = 340 meV which, at variance with a Slater-type description, is already open at 300 K and does not show significant temperature dependence even across T_N ~ 15 K. An LDA analysis with the inclusion of SO and Coulomb repulsion U reveals that, while the prodromes of an underlying insulating state are already found in LDA+SO, the correct gap magnitude can only be reproduced by LDA+SO+U, with U = 3 eV. This establishes Na2IrO3 as a novel type of Mott-like correlated insulator in which Coulomb and relativistic effects have to be treated on an equal footing.
@article{arxiv.1204.4471,
title = {Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap},
author = {R. Comin and G. Levy and B. Ludbrook and Z. -H. Zhu and C. N. Veenstra and J. A. Rosen and Yogesh Singh and P. Gegenwart and D. Stricker and J. N. Hancock and D. van der Marel and I. S. Elfimov and A. Damascelli},
journal= {arXiv preprint arXiv:1204.4471},
year = {2013}
}
Comments
Accepted in Physical Review Letters. Auxiliary and related material can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.html