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Title: Origins of ferromagnetism in transition-metal doped Si
Authors: Ko, V.
Teo, K.L. 
Liew, T. 
Chong, T.C. 
MacKenzie, M.
MacLaren, I.
Chapman, J.N.
Issue Date: 2008
Citation: Ko, V., Teo, K.L., Liew, T., Chong, T.C., MacKenzie, M., MacLaren, I., Chapman, J.N. (2008). Origins of ferromagnetism in transition-metal doped Si. Journal of Applied Physics 104 (3) : -. ScholarBank@NUS Repository.
Abstract: We present results of the magnetic, structural, and chemical characterizations of Mn+ -implanted Si displaying n -type semiconducting behavior and ferromagnetic ordering with Curie temperature, TC, well above room temperature. The temperature-dependent magnetization measured by superconducting quantum interference device from 5 to 800 K was characterized by three different critical temperatures (TC* ∼45 K, TC1 ∼630-650 K, and TC2 ∼805-825 K). Their origins were investigated using dynamic secondary ion mass spectroscopy and transmission electron microscopy (TEM) techniques, including electron energy loss spectroscopy, Z -contrast scanning TEM imaging, and electron diffraction. We provided direct evidences of the presence of a small amount of Fe and Cr impurities which were unintentionally doped into the samples together with the Mn+ ions as well as the formation of Mn-rich precipitates embedded in a Mn-poor matrix. The observed TC* is attributed to the Mn4 Si7 precipitates identified by electron diffraction. Possible origins of TC1 and TC2 are also discussed. Our findings raise questions regarding the origin of the high- TC ferromagnetism reported in many material systems without a careful chemical analysis. © 2008 American Institute of Physics.
Source Title: Journal of Applied Physics
ISSN: 00218979
DOI: 10.1063/1.2963485
Appears in Collections:Staff Publications

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