標題: Size dependent magnetization and high-vacuum annealing enhanced ferromagnetism in Zn(1-x)Co(x)O nanowires
作者: Jian, Wen-Bin
Chen, I-Jan
Liao, Tai-Ching
Ou, Yi-Ching
Nien, Cheng-Hsun
Wu, Zhong-Yi
Chen, Fu-Rong
Kai, Ji-Jung
Lin, Juhn-Jong
電子物理學系
物理研究所
Department of Electrophysics
Institute of Physics
關鍵字: diluted magnetic semiconductor;ZnCoO;nanowires;size effect;ferromagnetism
公開日期: 1-Jan-2008
摘要: Diameter controllable ZnO nanowires have been fabricated by thermal evaporation (vapor transport) with various sizes of gold nanoparticles as catalysts. Diluted magnetic semiconductor (DMS) Zn(1-x)Co(x)O nanowires were then made by high energy Co ion implantation. The as-implanted and the argon-annealed Zn(1-x)Co(x)O nanowires displayed weak ferromagnetism while the high-vacuum annealed nanowires exhibited strong ferromagnetic ordering at room temperature. Size dependent behavior has been observed in the magnetic field and temperature dependences of magnetization. The shrinkage of the nanowire diameter reduced the spontaneous magnetization as well as the hysteresis loops. Field cooled and zero-field cooled magnetization and coercivity measurements were performed between 2 and 300 K to study the evolution of magnetism from the weak to the strong ferromagnetic states. In particular, superparamagnetic features were observed and shown to be intrinsic characteristics of the DMS Zn(1-x)Co(x)O nanowires. The room-temperature spontaneous magnetization of individual Zn(1-x)Co(x)O nanowires was also established by using magnetic force microscope measurements.
URI: http://dx.doi.org/10.1166/jnn.2008.N13
http://hdl.handle.net/11536/9788
ISSN: 1533-4880
DOI: 10.1166/jnn.2008.N13
期刊: JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
Volume: 8
Issue: 1
起始頁: 202
結束頁: 211
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