title: Anisotropic ferromagnetism in substituted zinc oxide.
abstract: Room-temperature ferromagnetism is observed in (110) oriented ZnO films made from targets containing 5 at. % of Sc, Ti, V, Fe, Co, or Ni, but not Cr, Mn, or Cu ions. There are large moments, 2.6 micro(B) and 0.5 micro(B)/dopant atom for Co- and Ti-containing oxides, respectively. There is also a moment of 0.3 micro(B)/Sc. Magnetization is very anisotropic, with variations of up to a factor of 3 depending on the orientation of the applied field relative to the substrate. Results are interpreted in terms of a spin-split donor impurity-band model, which can account for ferromagnetism in insulating or conducting high-k oxides with concentrations of magnetic ions that lie far below the percolation threshold. Magnetic moments are associated with two-electron defects in the films as well as unpaired electrons of the 3d ions.
authors.affiliation: Physics Department, Trinity College, Dublin 2, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: Venkatesan
authors.forename: C B
authors.initials: CB
authors.lastname: Fitzgerald
authors.forename: J G
authors.initials: JG
authors.lastname: Lunney
authors.forename: J M D
authors.initials: JM
authors.lastname: Coey