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Absence of ferromagnetism in bulk polycrystalline Zn0.9Co0.1O

Yin, S. and Xu, M. and Yang, L. and Liu, J. and Rösner, H. and Hahn, H. and Gleiter, H. and Schild, D. and Doyle, S. and Liu, T. and Hu, T. and Takayama-Muromachi, E. and Jiang, J. (2006):
Absence of ferromagnetism in bulk polycrystalline Zn0.9Co0.1O.
In: Physical Review B, American Physical Society, pp. 224408-1, 73, (22), ISSN 1098-0121,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.73.224408],
[Article]

Abstract

The atomic structure and the magnetic properties of 5 and 10 at. % Co-doped ZnO samples prepared by a high-pressure and high-temperature method have been investigated by various techniques, including x-ray diffraction with Rietveld refinements, scanning electron microscopy, high-resolution transmission electron microscopy, nanometer-sized element mapping, x-ray photoelectron spectroscopy, near-edge x-ray absorption fine structure, and extended x-ray absorption fine structure and magnetization measurements. It is found that Co ions with a valence of 2+ substitute Zn ions in the wurtzite ZnO structure. No metallic or oxidic Co-rich clusters were detected in the samples. If Co2+ ions substitute Zn2+ ions, no intrinsic ferromagnetism is observed in ZnO at doping levels up to 10 at. % Co even down to 5 K. A paramagnetic behavior with partially antiferromagnetic interactions is observed. Thus, in bulk Co-doped ZnO system any observation of ferromagnetism is probably due to small clusters of second phase materials. However, in thin films the situation might be more complex, since other extrinsic influences, such as strain or proximity effects, may modify the electronic and magnetic properties.

Item Type: Article
Erschienen: 2006
Creators: Yin, S. and Xu, M. and Yang, L. and Liu, J. and Rösner, H. and Hahn, H. and Gleiter, H. and Schild, D. and Doyle, S. and Liu, T. and Hu, T. and Takayama-Muromachi, E. and Jiang, J.
Title: Absence of ferromagnetism in bulk polycrystalline Zn0.9Co0.1O
Language: English
Abstract:

The atomic structure and the magnetic properties of 5 and 10 at. % Co-doped ZnO samples prepared by a high-pressure and high-temperature method have been investigated by various techniques, including x-ray diffraction with Rietveld refinements, scanning electron microscopy, high-resolution transmission electron microscopy, nanometer-sized element mapping, x-ray photoelectron spectroscopy, near-edge x-ray absorption fine structure, and extended x-ray absorption fine structure and magnetization measurements. It is found that Co ions with a valence of 2+ substitute Zn ions in the wurtzite ZnO structure. No metallic or oxidic Co-rich clusters were detected in the samples. If Co2+ ions substitute Zn2+ ions, no intrinsic ferromagnetism is observed in ZnO at doping levels up to 10 at. % Co even down to 5 K. A paramagnetic behavior with partially antiferromagnetic interactions is observed. Thus, in bulk Co-doped ZnO system any observation of ferromagnetism is probably due to small clusters of second phase materials. However, in thin films the situation might be more complex, since other extrinsic influences, such as strain or proximity effects, may modify the electronic and magnetic properties.

Journal or Publication Title: Physical Review B
Volume: 73
Number: 22
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Joint Research Laboratory Nanomaterials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 13 Feb 2013 10:00
Official URL: http://dx.doi.org/10.1103/PhysRevB.73.224408
Identification Number: doi:10.1103/PhysRevB.73.224408
Funders: The authors would like to thank BSRF in Beijing, NSRL in Hefei, ANKA and HASYLAB in Germany, MAXlab in Sweden, and SPring8 and KEK in Japan for use of the synchrotron radiation facilities., Financial support from the National Natural Science Foundation of China (Grants Nos. 50341032 and 50425102), the Ministry of Science and Technology of China (Grant Nos. 2004/249/37-14 and 2004/250/ 31-01A),, the Ministry of Education of China (Grant Nos. 2.005E+10 and 2005-55), Zhejiang University, and Grants-in- Aid for Scientific Research (B) from Japan Society for the Promotion of Science (16340111 and 16076209) are gratefully acknowledged., One of us �JZJ� is grateful for support from FZK.
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