title: The electrical conductivity of post-perovskite in Earth's D'' layer.
abstract: Recent discovery of a phase transition from perovskite to post-perovskite suggests that the physical properties of Earth's lowermost mantle, called the D'' layer, may be different from those of the overlying mantle. We report that the electrical conductivity of (Mg0.9Fe0.1)SiO3 post-perovskite is >10(2) siemens per meter and does not vary greatly with temperature at the conditions of the D'' layer. A post-perovskite layer above the core-mantle boundary would, by electromagnetic coupling, enhance the exchange of angular momentum between the fluid core and the solid mantle, which can explain the observed changes in the length of a day on decadal time scales. Heterogeneity in the conductivity of the lowermost mantle is likely to depend on changes in chemistry of the boundary region, not fluctuations in temperature.
authors.affiliation: Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohta
authors.forename: Suzue
authors.initials: S
authors.lastname: Onoda
authors.forename: Kei
authors.initials: K
authors.lastname: Hirose
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Sinmyo
authors.forename: Katsuya
authors.initials: K
authors.lastname: Shimizu
authors.forename: Nagayoshi
authors.initials: N
authors.lastname: Sata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohishi
authors.forename: Akira
authors.initials: A
authors.lastname: Yasuhara