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

In this paper, we have synthesized and studied single-crystal Ba5AlIr2O11 that features dimer chains of two inequivalent octahedra occupied by tetravalent Ir4+(5d5) and pentavalent Ir5+(5d4) ions, respectively. Ba5AlIr2O11 is a Mott insulator that undergoes a subtle structural phase transition near TS=210K and a magnetic transition at TM=4.5K; the latter transition is surprisingly resistant to applied magnetic fields μoH≤12T but more sensitive to modest applied pressure (dTM/dp ≈ +0.61K/GPa). All results indicate that the phase transition at TS signals an enhanced charge order that induces electrical dipoles and strong dielectric response near TS. 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 S=3/2 nor J=1/2, but rather lies in an “intermediate” regime between these two states. Finally, the novel 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.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [1] ;  [1] ;  [5] ;  [6] ;  [1]
  1. Univ. of Kentucky, Lexington, KY (United States). Center for Advanced Materials. Dept. of Physics and Astronomy
  2. Univ. of Kentucky, Lexington, KY (United States). Center for Advanced Materials. Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division; Renmin Univ. of China, Beijing (China). Dept. of Physics
  3. Univ. of Kentucky, Lexington, KY (United States). Center for Advanced Materials. Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  4. Univ. of Kentucky, Lexington, KY (United States). Center for Advanced Materials. Dept. of Physics and Astronomy; Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Solid State Physics
  5. Inst. of Metal Physics, Ekaterinburg (Russian Federation); Ural Federal Univ., Ekaterinburg (Russian Federation). Dept. of Physics
  6. Univ. of Cologne (Germany). Inst. of Physics II
Publication Date:
OSTI Identifier:
1324136
Grant/Contract Number:
AC05-00OR22725; DMR-1265162; 13-02-00374; FSCX-14-61025-0
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 23; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Kentucky, Lexington, KY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF) (United States); Civil Research and Development Foundation (CRDF) (United States); Russian Foundation of Basic Research; China Scholarship Council
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY