کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1620385 1516387 2010 4 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The origin of ferromagnetism in Co-doped ZnO single crystalline films upon reducing annealings
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
The origin of ferromagnetism in Co-doped ZnO single crystalline films upon reducing annealings
چکیده انگلیسی
High-quality Zn0.95Co0.05O single crystalline films have been grown on a-plane sapphire substrates using molecular-beam epitaxy. The as-grown films show high resistivity and non-ferromagnetism at room temperature, and they become good conductive and ferromagnetic after annealing in Ar atmosphere or Ar(95%)/H2(5%) mixed-gas. Compared with weak ferromagnetism (0.16 μB/Co) in the Zn0.95Co0.05O film annealed in pure Ar atmosphere, the film annealed in the Ar/H2 mixed-gas shows much stronger ferromagnetism (0.82 μB/Co) at room temperature. For all of the samples, both of the X-ray diffraction and optical transmission spectrum analyses suggest the incorporation of Co2+ cations into wurtzite ZnO lattice. However, X-ray absorption studies based on synchronization radiation clearly indicate the presence of metallic Co clusters in the Zn0.95Co0.05O film upon thermal annealing in Ar/H2 mixed-gas. Our work demonstrates that minor ferromagnetic phases below the detection limit of conventional characterization techniques may exist in the transition-metal doped ZnO films, especially grown and/or annealed in the reducing atmosphere, and be responsible for the observed ferromagnetism.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Alloys and Compounds - Volume 492, Issues 1–2, 4 March 2010, Pages 31-34
نویسندگان
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