title: Tetrahedral magnetic order and the metal-insulator transition in the pyrochlore lattice of Cd2Os2O7.
abstract: Cd2Os2O7 shows a peculiar metal-insulator transition at 227 K with magnetic ordering in a frustrated pyrochlore lattice, but its magnetic structure in the ordered state and the transition origin are yet uncovered. We observed a commensurate magnetic peak by resonant x-ray scattering in a high-quality single crystal. X-ray diffraction and Raman scattering experiments confirmed that the transition is not accompanied with any spatial symmetry breaking. We propose a noncollinear all-in-all-out spin arrangement on the tetrahedral network made of Os atoms. Based on this we suggest that the transition is not caused by the Slater mechanism as believed earlier but by an alternative mechanism related to the formation of the specific tetrahedral magnetic order on the pyrochlore lattice in the presence of strong spin-orbit interactions.
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Yamaura
authors.forename: K
authors.initials: K
authors.lastname: Ohgushi
authors.forename: H
authors.initials: H
authors.lastname: Ohsumi
authors.forename: T
authors.initials: T
authors.lastname: Hasegawa
authors.forename: I
authors.initials: I
authors.lastname: Yamauchi
authors.forename: K
authors.initials: K
authors.lastname: Sugimoto
authors.forename: S
authors.initials: S
authors.lastname: Takeshita
authors.forename: A
authors.initials: A
authors.lastname: Tokuda
authors.forename: M
authors.initials: M
authors.lastname: Takata
authors.forename: M
authors.initials: M
authors.lastname: Udagawa
authors.forename: M
authors.initials: M
authors.lastname: Takigawa
authors.forename: H
authors.initials: H
authors.lastname: Harima
authors.forename: T
authors.initials: T
authors.lastname: Arima
authors.forename: Z
authors.initials: Z
authors.lastname: Hiroi