Kimber SAJ, Senn MS, Fratini S, Wu H, Hill AH, Manuel P, Attfield JP, Argyriou DN, Henry PF. Charge order at the frontier between the molecular and solid states in Ba3NaRu2O9.
PHYSICAL REVIEW LETTERS 2012;
108:217205. [PMID:
23003297 DOI:
10.1103/physrevlett.108.217205]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Indexed: 06/01/2023]
Abstract
We show that the valence electrons of Ba3NaRu2O9, which has a quasimolecular structure, completely crystallize below 210 K. Using an extended Hubbard model, we show that the charge ordering instability results from long-range Coulomb interactions. However, orbital ordering, metal-metal bonding, and formation of a partial spin gap enforce the magnitude of the charge separation. The striped charge order and frustrated hcp lattice of Ru2O9 dimers lead to competition with a quasidegenerate charge-melted phase under photoexcitation at low temperature. Our results establish a broad class of simple metal oxides as models for emergent phenomena at the border between the molecular and solid states.
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