Nano Archive

Size dependent magnetization and high-vacuum annealing enhanced ferromagnetism in Zn1-xCoxO nanowires

Jian, Wen-Bin and Chen, I-Jan and Liao, Tai-Ching and Ou, Yi-Ching and Nien, Cheng-Hsun and Wu, Zhong-Yi and Chen, Fu-Rong and Kai, Ji-Jung and Lin, Juhn-Jong (2008) Size dependent magnetization and high-vacuum annealing enhanced ferromagnetism in Zn1-xCoxO nanowires. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, 8 (1). pp. 202-211.

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Diameter controllable ZnO nanowires have been fabricated by thermal evaporation (vapor transport) with various sizes of gold nanoparticles as catalysts. Diluted magnetic semiconductor (DMS) Zn1-xCoxO nanowires were then made by high energy Co ion implantation. The as-implanted and the argon-annealed Zn1-xCoxO 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 Zn1-xCoxO nanowires. The room-temperature spontaneous magnetization of individual Zn1-xCoxO nanowires was also established by using magnetic force microscope measurements.

Item Type:Article
Uncontrolled Keywords:diluted magnetic semiconductor; ZnCoO; nanowires; size effect; ferromagnetism
Subjects:Physical Science > Nanomagnetics
ID Code:436
Deposited By:Farnush Anwar
Deposited On:12 Dec 2008 09:51
Last Modified:12 Dec 2008 09:51

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