Magnetism in Dopant-Free ZnO Nanoplates

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• 作者：Jung-Il Hong ; Jiil Choi ; Seung Soon Jang ; Jiyeong Gu ; Yangling Chang ; Gregory Wortman ; Robert L. Snyder ; Zhong Lin Wang
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：February 8, 2012
• 年：2012
• 卷：12
• 期：2
• 页码：576-581
• 全文大小：373K
• 年卷期：v.12,no.2(February 8, 2012)
• ISSN：1530-6992

文摘

It is known that bulk ZnO is a nonmagnetic material. However, the electronic band structure of ZnO is severely distorted when the ZnO is in the shape of a very thin plate with its dimension along the c-axis reduced to a few nanometers while keeping the bulk scale sizes in the other two dimensions. We found that the chemically synthesized ZnO nanoplates exhibit magnetism even at room temperature. First-principles calculations show a growing asymmetry in the spin distribution within the distorted bands formed from Zn (3d) and O (2p) orbitals with the reduction of thickness of the ZnO nanoplates, which is suggested to be responsible for the observed magnetism. In contrast, reducing the dimension along the a- or b-axes of a ZnO crystal does not yield any magnetism for ZnO nanowires that grow along c-axis, suggesting that the internal electric field produced by the large {0001} polar surfaces of the nanoplates may be responsible for the distorted electronic band structures of thin ZnO nanoplates.

Keywords:

Nanoplates; ZnO; magnetism; polar surfaces; electronic band