title: NaSrCo2F7, a Co(2+) pyrochlore antiferromagnet.
abstract: We report the crystal growth, by the Bridgeman-Stockbarger method, and the basic magnetic properties of a new cobalt-based pyrochlore, NaSrCo2F7. Single-crystal structure determination shows that Na and Sr are completely disordered on the non-magnetic large atom A sites, while magnetic [Formula: see text] Co(2+) fully occupies the pyrochlore lattice B sites. NaSrCo2F7 displays strong antiferromagnetic interactions ([Formula: see text]), a large effective moment ([Formula: see text]), and no spin freezing until 3 K. Thus, NaSrCo2F7 is a geometrically frustrated antiferromagnet with a frustration index [Formula: see text]. Ac susceptibility, dc susceptibility, and heat capacity are utilized to characterize the spin freezing. We argue that NaSrCo2F7 and the related material NaCaCo2F7 are examples of frustrated pyrochlore antiferromagnets with weak bond disorder.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Krizan
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava