Observation of all-in type tetrahedral displacements in nonmagnetic pyrochlore niobates

非磁性パイロクロア型ニオブ酸化物における全内方向四面体変位の観測

鳥越 秀平*; 石本 祐太朗*; 青石 優平*; 村川 寛*; 松村 大樹   ; 吉井 賢資  ; 米田 安宏   ; 西畑 保雄; 樹神 克明   ; 富安 啓輔*; 池田 一貴*; 中尾 裕則*; 野上 由夫*; 池田 直*; 大友 季哉*; 花咲 徳亮*

Torigoe, Shuhei*; Ishimoto, Yutaro*; Aoishi, Yuhei*; Murakawa, Hiroshi*; Matsumura, Daiju; Yoshii, Kenji; Yoneda, Yasuhiro; Nishihata, Yasuo; Kodama, Katsuaki; Tomiyasu, Keisuke*; Ikeda, Kazutaka*; Nakao, Hironori*; Nogami, Yoshio*; Ikeda, Naoshi*; Otomo, Toshiya*; Hanasaki, Noriaki*

We observed all-in type Nb tetrahedral displacement in nonmagnetic pyrochlore niobates ANbO (A = NdCa and YCa) through the analysis of the neutron pair distribution function and the extended X-ray absorption function spectroscopy. The all-in type Nb tetrahedral displacement, which has the character of a charge singlet state, is driven by the formation of the bonding orbital. The diffuse scattering in the X-ray diffraction, which has the resonant component in the Nb 3 edge, indicates that the all-in type Nb tetrahedral displacement has the periodicity with its short-range correlation.