科研之友
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摘要
The dramatic drop of about 2.5 orders of magnitude in the Zn vacancy magnetization with nanocrystal (NC) size was experimentally found in ZnO quantum dots in vacuum and air. We explain such an unusual behavior by the different contributions of spatial surface and core Zn vacancy configurations. With the increase of a NC size, the core contribution to the total NC magnetization becomes more pronounced. Therefore, the magnetization drop with NC size can be explained by the input of the core configuration, which has the lowest magnetic moment, 260 times lower than the magnetic moments of other surface or core configurations. In air the additional oxygen molecules on a NC surface can cause chemical reactions of dissociation along with the attachments of the NC oxygen atoms. Such configurations are different from those of the vacuum ones, resulting in the different NC size-dependence of the magnetic moment. Excellent agreement between the experiments and computations is reached.
- 出版日期2017-9-7
