title: Evidence of structural defect enhanced room-temperature ferromagnetism in Co-doped ZnO.
abstract: We report experimentally that room-temperature ferromagnetism of Co-doped ZnO is strongly correlated with structural defects, and that carriers involved in carrier-mediated exchange are by nature by-products of the creation of the defects. On the other hand, the carrier concentration has pronounced influences on the absorption edge in optical transmission spectra of epitaxial Co:ZnO films, in which both a blue-shift and a red-shift are observed. Furthermore, high-temperature annealing results in evolution of the local Co structure from Co(2+) replacing Zn(2+) to a Co(3)O(4)-based phase, which most likely accounts for the transition from ferromagnetism to paramagnetism in the Co:ZnO films.
authors.affiliation: Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: C
authors.initials: C
authors.lastname: Song
authors.forename: S N
authors.initials: SN
authors.lastname: Pan
authors.forename: X J
authors.initials: XJ
authors.lastname: Liu
authors.forename: X W
authors.initials: XW
authors.lastname: Li
authors.forename: F
authors.initials: F
authors.lastname: Zeng
authors.forename: W S
authors.initials: WS
authors.lastname: Yan
authors.forename: B
authors.initials: B
authors.lastname: He
authors.forename: F
authors.initials: F
authors.lastname: Pan