Structural, electronic, and magnetic properties of nearly ideal Jeff= 12 iridium halides

D. Reig-I-Plessis, T. A. Johnson, K. Lu, Q. Chen, J. P.C. Ruff, M. H. Upton, T. J. Williams, S. Calder, H. D. Zhou, J. P. Clancy, A. A. Aczel, G. J. MacDougall

Research output: Contribution to journalArticlepeer-review


Heavy transition metal magnets with Jeff=12 electronic ground states have attracted recent interest due to their penchant for hosting new classes of quantum spin liquids and superconductors. Unfortunately, model systems with ideal Jeff=12 states are scarce due to the importance of noncubic local distortions in most candidate materials. In this work, we identify a family of iridium halide systems [i.e., K2IrCl6, K2IrBr6, (NH4)2IrCl6, and Na2IrCl6·6(H2O)] with Ir4+ electronic ground states exhibiting extremely small deviations from the ideal Jeff=12 limit. We also find ordered magnetic ground states for the three anhydrous systems, with single-crystal neutron diffraction on K2IrBr6 revealing type-I antiferromagnetism. This spin configuration is consistent with expectations for significant Kitaev exchange in a face-centered-cubic magnet. This work establishes that incorporating isolated IrX6 octahedra in materials, where X is a halogen ion with a low electronegativity, is an effective design principle for realizing unprecedented proximity to the pure Jeff=12 state. At the same time, we highlight undeniable deviations from this ideal state, even in clean materials with ideal IrX6 octahedra as inferred from the global cubic crystal structures.

Original languageEnglish (US)
Article number124407
JournalPhysical Review Materials
Issue number12
StatePublished - Dec 17 2020
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Physics and Astronomy (miscellaneous)


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