Magnetism in dopant-free ZnO nanoplates.
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.
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA. jungil.hong@mse.gatech.edu
Jung-Il
JI
Hong
Jiil
J
Choi
Seung Soon
SS
Jang
Jiyeong
J
Gu
Yangling
Y
Chang
Gregory
G
Wortman
Robert L
RL
Snyder
Zhong Lin
ZL
Wang
D008280:Magnetics; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
D015034:Zinc Oxide