Deposition of Co nano-particles in a CoO/Al₂O₃ matrix by magnetron sputtering

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• 作者：M. Gamino ; J.T.D. de Oliveira ; C.R. dos Santos ; F. Bohn ; L.F. Schelp ; J.C. Denardin
• 关键词：Exchange bias ; Granular systems ; Superparamagnetism
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：320
• 期：14
• 页码：e308-e311
• 全文大小：265 K

文摘

We have explored the use of sequential sputtering as an alternative way of growing Co clusters inside an antiferromagnetic matrix of CoO. The samples are composed of 10 bi- or tri-layers and have been deposited by direct magnetron sputtering of Co, CoO and Al₂O₃ targets. Transmission electron microscopy and impedance spectroscopy measurements show that the direct deposition of Co over CoO does not favor the Volmer–Weber tridimensional mode in the tested range of Co nominal thicknesses. In the samples where an Al₂O₃ layer is formed prior to the Co deposition, Co aggregates of nano-size are formed and retained when the empty space is filled by CoO. Some preliminary results of the magnetization as a function of temperature are presented and discussed.