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arXiv · 1505.01436

Coexisting charge and magnetic orders in the dimer-chain iridate Ba5AlIr2O11

J. Terzic·J. C. Wang·Feng Ye·W. H. Song·S. J. Yuan·S. Aswartham·L. E. DeLong·S. V. Streltsov·D. I. Khomskii·G. Cao
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Abstract

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.

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J. Terzic, J. C. Wang, Feng Ye, W. H. Song, S. J. Yuan, S. Aswartham, L. E. DeLong, S. V. Streltsov, D. I. Khomskii, G. Cao. 2015-05-06. Coexisting charge and magnetic orders in the dimer-chain iridate Ba5AlIr2O11. https://arxiv.org/abs/1505.01436

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