title: Magnetite 3D colloidal crystals formed in the early solar system 4.6 billion years ago.
abstract: Three-dimensional colloidal crystals made of ferromagnetic particles, such as magnetite (Fe(3)O(4)), cannot be synthesized in principle because of the strong attractive magnetic interaction. However, we discovered colloidal crystals composed of polyhedral magnetite nanocrystallites of uniform size in the range of a few hundred nanometers in the Tagish Lake meteorite. Those colloidal crystals were formed 4.6 billion years ago and thus are much older than natural colloidal crystals on earth, such as opals, which formed about 100 million years ago. We found that the size of each individual magnetite particle determines its morphology, which in turn plays an important role in deciding the packing structure of the colloidal crystals. We also hypothesize that each particle has a flux-closed magnetic domain structure, which reduces the interparticle magnetic force significantly.
authors.affiliation: Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Sendai 980-8578, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nozawa
authors.forename: Katsuo
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Willem
authors.initials: W
authors.lastname: van Enckevort
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nakamura
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kimura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miura
authors.forename: Hisao
authors.initials: H
authors.lastname: Satoh
authors.forename: Ken
authors.initials: K
authors.lastname: Nagashima
authors.forename: Makoto
authors.initials: M
authors.lastname: Konoto