Regular-triangle trimer and charge order preserving the Anderson condition in the pyrochlore structure of CsW 2 O 6

• Published in: Nature communications Vol. 11; no. 1; p. 3144
• Main Authors: Okamoto, Yoshihiko, Amano, Haruki, Katayama, Naoyuki, Sawa, Hiroshi, Niki, Kenta, Mitoka, Rikuto, Harima, Hisatomo, Hasegawa, Takumi, Ogita, Norio, Tanaka, Yu, Takigawa, Masashi, Yokoyama, Yasunori, Takehana, Kanji, Imanaka, Yasutaka, Nakamura, Yuto, Kishida, Hideo, Takenaka, Koshi
• Format: Journal Article
• Language: English
• Published: England 19.06.2020
• ISSN: 2041-1723

Since the discovery of the Verwey transition in magnetite, transition metal compounds with pyrochlore structures have been intensively studied as a platform for realizing remarkable electronic phase transitions. We report on a phase transition that preserves the cubic symmetry of the β-pyrochlore oxide CsW O , where each of W 5d electrons are confined in regular-triangle W trimers. This trimer formation represents the self-organization of 5d electrons, which can be resolved into a charge order satisfying the Anderson condition in a nontrivial way, orbital order caused by the distortion of WO octahedra, and the formation of a spin-singlet pair in a regular-triangle trimer. An electronic instability due to the unusual three-dimensional nesting of Fermi surfaces and the strong correlations of the 5d electrons characteristic of the pyrochlore oxides are both likely to play important roles in this charge-orbital-spin coupled phenomenon.