title: Negligible magnetism in excellent structural quality Cr(x)Ti(1-x)O(2) anatase: contrast with high-T(C) ferromagnetism in structurally defective Cr(x)Ti(1-x)O(2).
abstract: We reexamine the mechanism of ferromagnetism in doped TiO(2) anatase, using epitaxial Cr:TiO(2) with excellent structural quality as a model system. In contrast to highly oriented but defective Cr:TiO(2) (approximately 0.5 micro(b)/Cr), these structurally superior single crystal films exhibit negligible ferromagnetism. Similar results were obtained for Co:TiO(2). We show for the first time that charge-compensating oxygen vacancies alone, as predicted by F-center mediated exchange, are not sufficient to activate ferromagnetism. Instead, the onset of ferromagnetism correlates with the presence of structural defects.
authors.affiliation: Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Kaspar
authors.forename: S M
authors.initials: SM
authors.lastname: Heald
authors.forename: C M
authors.initials: CM
authors.lastname: Wang
authors.forename: J D
authors.initials: JD
authors.lastname: Bryan
authors.forename: T
authors.initials: T
authors.lastname: Droubay
authors.forename: V
authors.initials: V
authors.lastname: Shutthanandan
authors.forename: S
authors.initials: S
authors.lastname: Thevuthasan
authors.forename: D E
authors.initials: DE
authors.lastname: McCready
authors.forename: A J
authors.initials: AJ
authors.lastname: Kellock
authors.forename: D R
authors.initials: DR
authors.lastname: Gamelin
authors.forename: S A
authors.initials: SA
authors.lastname: Chambers