Origin of the insulating state in honeycomb iridates and rhodates

I. I. Mazin, S. Manni, K. Foyevtsova, Harald Olaf Jeschke, P. Gegenwart, Roser Valentí

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Abstract

A burning question in the emerging field of spin-orbit driven insulating iridates, such as Na2IrO3 and Li2IrO 3, is whether the observed insulating state should be classified as a Mott-Hubbard insulator derived from a half-filled relativistic j eff=1/2 band or as a band insulator where the gap is assisted by spin-orbit interaction or Coulomb correlations or both. The difference between these two interpretations is that only for the former strong spin-orbit coupling (λâ‰W, where W is the bandwidth) is essential. We have synthesized the isostructural and isoelectronic Li2RhO3 and report its electrical resistivity and magnetic susceptibility. Remarkably, it shows insulating behavior together with fluctuating effective S=1/2 moments, similar to Na2IrO3 and Li2IrO3, although in Rh4+ (4d5) the spin-orbit coupling is greatly reduced. We show that this behavior has a nonrelativistic one-electron origin (although Coulomb correlations assist in opening the gap) and can be traced to the formation of quasimolecular orbitals, similar to those in Na2IrO 3.

Original languageEnglish
Article number035115
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume88
Issue number3
DOIs
Publication statusPublished - Jul 12 2013
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

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