Fluctuant Magnetism in Metal Oxide Nanocrystals Capped with Surfactants
Fluctuant Magnetism in Metal Oxide Nanocrystals Capped with Surfactants
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DOI：
10.1103/physrevb.88.085437
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发表时间：
2013-08
影响因子：
3.7
通讯作者：
Jianhui Zhang;S. Xiong;Xinglong Wu;A. Thurber;Michael Jones;Minhao Gu;Zhongda Pan;D. Tenne;C. Hanna;Youwei Du;A. Punnoose
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文献类型：
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作者：
Jianhui Zhang;S. Xiong;Xinglong Wu;A. Thurber;Michael Jones;Minhao Gu;Zhongda Pan;D. Tenne;C. Hanna;Youwei Du;A. Punnoose
我们通过实验证明ZnO、TiO2、ceo2、a和SnO2纳米晶体（NCs）的磁性随表面活性剂类型和浓度的变化而波动。通过开发一种强制水解方法，并对这些NC的合成和表面活性剂的覆盖进行额外的后处理，我们有效地避免了尺寸、形状和磁性杂质对NC磁性行为的影响，从而揭示了覆盖表面活性剂对NC磁性的系统性影响。x射线光电子能谱结果和理论计算清楚地表明，磁性随表面活性剂浓度的波动可以归因于自旋的周期性变化，这是由表面活性剂向nc的浓度依赖的电子转移引起的。我们的研究结果不仅解释了之前报道的表面活性剂引起的看似不规则的磁性，而且为调整或优化NC磁性提供了有效的方法。
We demonstrate experimentally that magnetism in ZnO, TiO2 ,C eO2 ,a nd SnO2 nanocrystals (NCs) has a fluctuant nature that varies with capping surfactant type and concentration. By developing a forced hydrolysis approach with additional postprocessing for the synthesis and surfactant capping of these NCs, we effectively avoid the influence of size, shape, and magnetic impurities on the magnetic behavior of NCs, thus revealing the systematic influence of the capping surfactants on the NC magnetism. The x-ray photoelectron spectroscopy results and theoretical calculations clearly show that the magnetism fluctuation with surfactant concentration can be attributed to the periodic variation of spins, which arises from the concentration-dependent electron transfer from surfactants to NCs. Our results not only explain the previously reported seemingly irregular magnetism induced by capping surfactants but also provide an effective approach to tune or optimize the NC magnetism.