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Title: Local Moment Instability of Os in Honeycomb Li 2.15Os 0.85O 3

Abstract

Compounds with honeycomb structures occupied by strong spin orbit coupled (SOC) moments are considered to be candidate Kitaev quantum spin liquids. Here we present the first example of Os on a honeycomb structure, Li 2.15(3)Os 0.85(3)O3 (C2/c, a = 5.09 Å, b = 8.81 Å, c = 9.83 Å, β = 99.3°). Neutron diffraction shows large site disorder in the honeycomb layer and X-ray absorption spectroscopy indicates a valence state of Os (4.7 ± 0.2), consistent with the nominal concentration. We observe a transport band gap of Δ = 243 ± 23 meV, a large van Vleck susceptibility, and an effective moment of 0.85 μ B, much lower than expected from 70% Os(+5). No evidence of long range order is found above 0.10 K but a spin glass-like peak in ac-susceptibility is observed at 0.5 K. The specific heat displays an impurity spin contribution in addition to a power law ∝T (0.63±0.06). Applied density functional theory (DFT) leads to a reduced moment, suggesting incipient itineracy of the valence electrons, and finding evidence that Li over stoichiometry leads to Os(4+)–Os(5+) mixed valence. Lastly, this local picture is discussed in light of the site disorder and a possible underlying quantum spin liquidmore » state.« less

Authors:
 [1];  [2]; ORCiD logo [1];  [3];  [3];  [4];  [5];  [2];  [1]
  1. Oregon State Univ., Corvallis, OR (United States)
  2. Univ. of California Santa Cruz, Santa Cruz, CA (United States)
  3. Univ. of California Davis, Davis, CA (United States)
  4. Univ. of Colorado, Denver, CO (United States)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1435605
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Condensed-matter physics; Magnetic materials

Citation Formats

Wallace, M. K., LaBarre, P. G., Li, Jun, Pi, S. -T., Pickett, W. E., Dessau, D. S., Haskel, D., Ramirez, A. P., and Subramanian, M. A. Local Moment Instability of Os in Honeycomb Li2.15Os0.85O3. United States: N. p., 2018. Web. doi:10.1038/s41598-018-25028-0.
Wallace, M. K., LaBarre, P. G., Li, Jun, Pi, S. -T., Pickett, W. E., Dessau, D. S., Haskel, D., Ramirez, A. P., & Subramanian, M. A. Local Moment Instability of Os in Honeycomb Li2.15Os0.85O3. United States. doi:10.1038/s41598-018-25028-0.
Wallace, M. K., LaBarre, P. G., Li, Jun, Pi, S. -T., Pickett, W. E., Dessau, D. S., Haskel, D., Ramirez, A. P., and Subramanian, M. A. Thu . "Local Moment Instability of Os in Honeycomb Li2.15Os0.85O3". United States. doi:10.1038/s41598-018-25028-0. https://www.osti.gov/servlets/purl/1435605.
@article{osti_1435605,
title = {Local Moment Instability of Os in Honeycomb Li2.15Os0.85O3},
author = {Wallace, M. K. and LaBarre, P. G. and Li, Jun and Pi, S. -T. and Pickett, W. E. and Dessau, D. S. and Haskel, D. and Ramirez, A. P. and Subramanian, M. A.},
abstractNote = {Compounds with honeycomb structures occupied by strong spin orbit coupled (SOC) moments are considered to be candidate Kitaev quantum spin liquids. Here we present the first example of Os on a honeycomb structure, Li2.15(3)Os0.85(3)O3 (C2/c, a = 5.09 Å, b = 8.81 Å, c = 9.83 Å, β = 99.3°). Neutron diffraction shows large site disorder in the honeycomb layer and X-ray absorption spectroscopy indicates a valence state of Os (4.7 ± 0.2), consistent with the nominal concentration. We observe a transport band gap of Δ = 243 ± 23 meV, a large van Vleck susceptibility, and an effective moment of 0.85 μB, much lower than expected from 70% Os(+5). No evidence of long range order is found above 0.10 K but a spin glass-like peak in ac-susceptibility is observed at 0.5 K. The specific heat displays an impurity spin contribution in addition to a power law ∝T(0.63±0.06). Applied density functional theory (DFT) leads to a reduced moment, suggesting incipient itineracy of the valence electrons, and finding evidence that Li over stoichiometry leads to Os(4+)–Os(5+) mixed valence. Lastly, this local picture is discussed in light of the site disorder and a possible underlying quantum spin liquid state.},
doi = {10.1038/s41598-018-25028-0},
journal = {Scientific Reports},
number = 1,
volume = 8,
place = {United States},
year = {Thu Apr 26 00:00:00 EDT 2018},
month = {Thu Apr 26 00:00:00 EDT 2018}
}

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