Defect-mediated ferromagnetism in insulating Co-doped anatase TiO2 thin films
Defect-mediated ferromagnetism in insulating Co-doped anatase TiO2 thin films
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DOI：
10.1103/physrevb.78.014409
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发表时间：
2008-07
影响因子：
3.7
通讯作者：
K. Roberts;M. Varela;S. Rashkeev;S. Pantelides;S. Pennycook;K. Krishnan
中科院分区：
文献类型：
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作者：
K. Roberts;M. Varela;S. Rashkeev;S. Pantelides;S. Pennycook;K. Krishnan
最近在过渡金属掺杂氧化物中发现的室温铁磁性使它们成为新的自旋电子学技术的独特材料。然而，导致这种行为的机制仍然难以捉摸。在这里，我们使用Z-衬度扫描透射电子显微镜图像的Co和发现，在Co掺杂的TiO 2薄膜的磁相组成的间隙Co原子均匀分布在晶格的超结构。在Ti L2，3边缘处的能量损失近边缘结构的详细分析表明，通过生长后真空退火激活铁磁性涉及Co-Ti 3 +-氧空位缺陷复合物的产生。第一性原理，自旋极化密度泛函理论计算证实，这些缺陷复合物具有最低的能量配置和它们的磁矩是在与实验观察。
The room temperature ferromagnetism recently discovered in transition metal doped oxides makes of them unique materials for new spintronic technologies. However, the mechanism responsible for this behavior has remained elusive. Here we use Z-contrast scanning transmission electron microscopy to image the Co and find that the magnetic phase in Co doped TiO2 films consists of a superstructure of interstitial Co atoms homogeneously distributed in the anatase lattice. Detailed analysis of the energy-loss near edge structure at the Ti L2,3 edge shows that the activation of ferromagnetism by post growth vacuum annealing involves the creation of Co - Ti3+- oxygen vacancy defect complexes. First-principles, spin-polarized density functional theory calculations confirm that these defect complexes have the lowest energy configuration and that their magnetic moment is in agreement with experimental observations.