Abstract
We synthesize and study single crystals of a new double-perovskite . Despite two strongly unfavorable conditions for magnetic order, namely, pentavalent ions which are anticipated to have singlet ground states in the strong spin-orbit coupling (SOC) limit and geometric frustration in a face-centered cubic structure formed by the ions, we observe this iridate to undergo a novel magnetic transition at temperatures below 1.3 K. We provide compelling experimental and theoretical evidence that the origin of magnetism is in an unusual interplay between strong noncubic crystal fields, local exchange interactions, and “intermediate-strength” SOC. provides a rare example of the failed dominance of SOC in the iridates.
- Received 8 November 2013
DOI:https://doi.org/10.1103/PhysRevLett.112.056402
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