V Laboratory
Department of Physics
Nagoya University
Furocho, Chikusa, Nagoya

Single-crystalline x-ray diffraction study on Ba4Ru3O10

Multiple degrees of freedom of d electrons and their correlation effect are a fundamental concept for various electronic and magnetic states realized in transition-metal oxides. Furthermore, in several oxide compounds consisting a multimeric complex of oxygen octahedra, the internal charge degree of freedom in the multimer is of importance to understand their electronic state. Here, we perform a single-crystalline x-ray diffraction study on a ruthenium oxide Ba4Ru3O10, which consists of Ru3O12 trimers. We find a significant distribution of Ru-O distances within the trimer. A bond valence sum calculation suggests that the charge disproportionation within the trimer emerges even at room temperature, which we ascribe to molecular orbital formation in the trimer. Our present study shows an importance of the internal degree of freedom in the multimer to clarify the electronic states in multimer-based oxide compounds.

"X-ray Crystal Structure Analysis and the Ru Valence of Ba4Ru3O10 Single Crystals"
by Taichi Igarashi, Yoshio Nogami, Yannick Klein, Gwenaelle Rousse, Ryuji Okazaki, Hiroki Taniguchi, Yukio Yasui, Ichiro Terasaki
J. Phys. Soc. Jpn. 82 (2013) 104603.

(Left) Crystal structure of Ba4Ru3O10. (Right) Ru3O12 trimer.