Abstract
We have synthesized and studied single-crystal that features dimer chains of two inequivalent octahedra occupied by tetravalent and pentavalent ions, respectively. is a Mott insulator that undergoes a subtle structural phase transition near and a magnetic transition at ; the latter transition is surprisingly resistant to applied magnetic fields but more sensitive to modest applied pressure . All results indicate that the phase transition at signals an enhanced charge order that induces electrical dipoles and strong dielectric response near . It is clear that the strong covalency and spin-orbit interaction (SOI) suppress double exchange in Ir dimers and stabilize a novel magnetic state that is neither nor , but rather lies in an “intermediate” regime between these two states. The novel behavior of therefore provides unique insights into the physics of SOI along with strong covalency in competition with double-exchange interactions of comparable strength.
- Received 26 April 2015
- Revised 3 June 2015
DOI:https://doi.org/10.1103/PhysRevB.91.235147
©2015 American Physical Society