We have synthesized and studied single-crystal Ba5AlIr2O11 that features dimer chains of two inequivalent octahedra occupied by tetravalent and pentavalent ions, respectively. Ba5AlIr2O11 is a Mott insulator that undergoes a subtle structural phase transition near 210 K and a magnetic transition at 4.5 K; the latter transition is surprisingly resistant to applied magnetic fields up to 12 T, but sensitive to modest applied pressure. All results indicate that the phase transition at 210 K signals an enhanced charge order that induces electrical dipoles and strong dielectric response near 210 K. It is clear that the strong covalency and spin-orbit interaction (SOI) suppress double exchange in Ir dimers and stabilize a novel magnetic state. The behavior of Ba5AlIr2O11 therefore provides unique insights into the physics of SOI along with strong covalency in competition with double exchange interactions of comparable strength.
@article{arxiv.1505.01436,
title = {Coexisting charge and magnetic orders in the dimer-chain iridate Ba5AlIr2O11},
author = {J. Terzic and J. C. Wang and Feng Ye and W. H. Song and S. J. Yuan and S. Aswartham and L. E. DeLong and S. V. Streltsov and D. I. Khomskii and G. Cao},
journal= {arXiv preprint arXiv:1505.01436},
year = {2015}
}
Comments
6 figures, 20 pages. arXiv admin note: text overlap with arXiv:1505.00877