Room Temperature Ferromagnetism in D-D Neutron Irradiated ZnO Single Crystals
Room Temperature Ferromagnetism in D-D Neutron Irradiated ZnO Single Crystals
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DOI：
10.1007/s10948-019-05410-3
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发表时间：
2020-05
影响因子：
1.8
通讯作者：
H. Liu;G. Li;D. E;N. Xu;Q. Lin;X. D. Gao;C. L. Wang
中科院分区：
文献类型：
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作者：
H. Liu;G. Li;D. E;N. Xu;Q. Lin;X. D. Gao;C. L. Wang
由于锌空位（VZn）缺陷，在室温下观察到ZnO单晶的铁磁性。利用D-D中子辐照调节缺陷的浓度和类型，避免杂质元素的干扰。D-D中子主要与ZnO单晶发生弹性碰撞，产生VZn、氧空位（VO）等点缺陷，缺陷的密度和种类与中子辐照通量有关。饱和磁化强度（Ms）随辐照通量的增大先增大后减小，说明vzn浓度存在一个最优值。当中子通量大于5× 109n/cm2时，更不稳定的vzn与VOto结合形成锌氧距离（VZnO），说明中子辐照改变了缺陷类型。vzno产生较小的磁矩；因此，m减小了。为了进一步验证RTFM的来源，我们利用CASTEP模块计算了ZnO中天然空位缺陷的磁性和结构性质。vzn团簇的磁矩为2.12μ b，其中最邻近vzn和von形成的vzno团簇磁矩为2.09μ b，而3von团簇的磁矩为1μ b。结合实验和CASTEP计算结果，vzs是RTFM最可能的起源。
Room temperature ferromagnetism (RTFM) was observed in unirradiated ZnO single crystal owing to zinc vacancy (VZn) defects. D-D neutron irradiation was used to regulate the defect concentration and types avoiding interference of impurity elements. D-D neutron mainly collides elastically with ZnO single crystals, producing VZn, oxygen vacancy (VO), and other point defects, the density and kind of defect associated with neutron irradiation fluence. It can be found the saturation magnetization (Ms) first increases and then decreases with the irradiation fluence increases, meaning there is an optimum value for VZnconcentration. When the neutron fluence is greater than 5× 109n/cm2, more unstable VZncombined with VOto form zinc-oxygen divacancy (VZnO), indicating neutron irradiation changes the defect types. VZnOinduces a smaller magnetic moment; thus, the Msdecreased. To further verify the origin of RTFM, the CASTEP module was employed to calculate the magnetic and structural properties of native vacancy defects in ZnO. VZninduces 2.12μBmagnetic moment, and only VZnOformed by the nearest VZnand VOhas 2.09μBmagnetic moment, while 3VOcluster introduces a magnetic moment of1μB. Combined experiment and CASTEP calculation results, VZnis the most likely origin of RTFM.