Open AccessDefect-induced magnetism in undoped wide band gap oxides: Zinc vacancies in ZnO as an example
Author(s) -
Guozhong Xing,
Ying-Bo Lü,
Yufeng Tian,
Jiabao Yi,
Chaesung Lim,
Yongfeng Li,
G. P. Li,
D. D. Wang,
Bin Yao,
Jiafeng Ding,
Yuan Ping Feng,
Tom Wu
Publication year - 2011
Publication title -
aip advances
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 58
ISSN - 2158-3226
DOI - 10.1063/1.3609964
Subject(s) - ferromagnetism , materials science , magnetism , photoluminescence , molecular beam epitaxy , zinc , condensed matter physics , band gap , magnetic semiconductor , density functional theory , wide bandgap semiconductor , acceptor , epitaxy , chemistry , optoelectronics , nanotechnology , layer (electronics) , computational chemistry , metallurgy , physics
To shed light on the mechanism responsible for the weak ferromagnetism in undoped wide band gap oxides, we carry out a comparative study on ZnO thin films prepared using both sol-gel and molecular beam epitaxy (MBE) methods. Compared with the MBE samples, the sol-gel derived samples show much stronger room temperature ferromagnetism with a magnetic signal persisting up to ∼740 K, and this ferromagnetic order coexists with a high density of defects in the form of zinc vacancies. The donor-acceptor pairs associated with the zinc vacancies also cause a characteristic orange-red photoluminescence in the sol-gel films. Furthermore, the strong correlation between the ferromagnetism and the zinc vacancies is confirmed by our first-principles density functional theory calculations, and electronic band alteration as a result of defect engineering is proposed to play the critical role in stabilizing the long-range ferromagnetism
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