Co-metal clustering as the origin of ferromagnetism in Co-doped ZnO thin films
Co-metal clustering as the origin of ferromagnetism in Co-doped ZnO thin films
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DOI：
10.1063/1.1650915
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发表时间：
2004-02
影响因子：
4
通讯作者：
J. Park;Min Gyu Kim;H. Jang;S. Ryu;Young Mo Kim
中科院分区：
文献类型：
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作者：
J. Park;Min Gyu Kim;H. Jang;S. Ryu;Young Mo Kim
使用钴掺杂 ZnO 薄膜作为 II-VI 基稀释磁性半导体的原型示例，研究了 ZnO 基系统中铁磁性的起源。尽管纤锌矿ZnO中Co离子在原子尺度上溶解，但磁化温度曲线和磁化场曲线都表明Zn1−xCoxO薄膜在x≤0.12时具有顺磁性。另一方面，x大于0.12的Zn1−xCoxO薄膜以Co金属团簇为特征，并且明显表现出室温铁磁性。零场冷却和场冷却曲线之间的差异进一步表明Co掺杂ZnO薄膜（x>0.12）是超顺磁性的，并且观察到的铁磁性源自纳米尺寸的Co团簇。
The origin of ferromagnetism in ZnO-based systems was investigated using Co-doped ZnO thin films as prototypical examples of II–VI-based diluted magnetic semiconductors. In spite of the atomic-scale dissolution of Co ions in wurtzite ZnO, both the magnetization-temperature curve and the magnetization-field curve demonstrated that Zn1−xCoxO thin films were paramagnetic for x⩽0.12. On the other hand, Zn1−xCoxO films with x greater than 0.12 were characterized by the Co-metal clustering and apparently showed room-temperature ferromagnetism. The discrepancy between the zero-field cooling and the field cooling curves further indicates that Co-doped ZnO films (for x>0.12) are superparamagnetic and the observed ferromagnetism originates from the nanometer-sized Co clusters.