title: Paramagnetism and antiferromagnetic interactions in single-phase Fe-implanted ZnO.
abstract: As the intrinsic origin of the high-temperature ferromagnetism often observed in wide-gap dilute magnetic semiconductors becomes increasingly debated, there is a growing need for comprehensive studies on the single-phase region of the phase diagram of these materials. Here we report on the magnetic and structural properties of Fe-doped ZnO prepared by ion implantation of ZnO single crystals. A detailed structural characterization shows that the Fe impurities substitute for Zn in ZnO in a wurtzite Zn(1-x)Fe(x)O phase which is coherent with the ZnO host. In addition, the density of beam-induced defects is progressively decreased by thermal annealing up to 900 ° C, from highly disordered after implantation to highly crystalline upon subsequent annealing. Based on a detailed analysis of the magnetometry data, we demonstrate that isolated Fe impurities occupying Zn-substitutional sites behave as localized paramagnetic moments down to 2 K, irrespective of the Fe concentration and the density of beam-induced defects. With increasing local concentration of Zn-substitutional Fe, strong nearest-cation-neighbor antiferromagnetic interactions favor the antiparallel alignment of the Fe moments.
authors.affiliation: Instituut voor Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium. IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Universidade do Porto, 4169-007 Porto, Portugal. Instituto Tecnológico e Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, 2686-953 Sacavém, Portugal.
authors.forename: L M C
authors.initials: LM
authors.lastname: Pereira
authors.forename: U
authors.initials: U
authors.lastname: Wahl
authors.forename: J G
authors.initials: JG
authors.lastname: Correia
authors.forename: M J
authors.initials: MJ
authors.lastname: Van Bael
authors.forename: K
authors.initials: K
authors.lastname: Temst
authors.forename: A
authors.initials: A
authors.lastname: Vantomme
authors.forename: J P
authors.initials: JP
authors.lastname: Araújo
mesh_terms: D003198:Computer Simulation; D007501:Iron / Q000737:chemistry* / Q000528:radiation effects*; D060526:Magnetic Fields; D008956:Models, Chemical; D008958:Models, Molecular; D015034:Zinc Oxide / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D007501:Iron; D015034:Zinc Oxide