Origin of ferromagnetism in ZnO/CoFe multilayers: Diluted magnetic semiconductor or clustering effect?
Origin of ferromagnetism in ZnO/CoFe multilayers: Diluted magnetic semiconductor or clustering effect?
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DOI：
10.1063/1.1812844
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发表时间：
2004-10
影响因子：
4
通讯作者：
J. Huang;H. Hsu;Y. M. Hu;Chih‐Hao Lee;Yen-Chun Huang;Min-Shyong Lin
中科院分区：
文献类型：
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作者：
J. Huang;H. Hsu;Y. M. Hu;Chih‐Hao Lee;Yen-Chun Huang;Min-Shyong Lin
用离子束溅射法在α-Al_2 O_3（0001）衬底上外延生长了标称厚度为x=1，2，5的[ZnO（20 A）scinCo_（0.7）Fe_（0.3）（xA）]_（25）多层膜。报道了在6- 350 K温度范围内的磁性和X射线吸收谱（XAS）结构探测。以上室温铁磁性已观察到x=1和x=2 ML，而超顺磁性行为占主导地位的x=5 ML。x=1和x=5 ML的场冷磁化强度-温度M（T）曲线可以分别用标准的三维（3D）自旋波和Curie-Weiss模型拟合。然而，对于x=2 ML，既不是3D自旋波也不是Curie-Weiss模型，而是两者的组合拟合M-T曲线。X射线吸收光谱研究和磁性测量进一步揭示了x=1的样品表现为稀磁半导体（DMS）ML，而x=2的样品表现为DMS和CoFe团簇的混合结构.一个主要的CL…
Epitaxial growth of (0001) oriented [ZnO(20A)∕Co0.7Fe0.3(xA)]25 multilayers (MLs) with nominal thickness x=1, 2 and 5 has been prepared on α-Al2O3 (0001) substrate by ion-beam sputtering. The magnetic properties over a temperature range of 6–350K and structures probing by x-ray absorption spectroscopy (XAS) are reported. Above room-temperature ferromagnetism has been observed for x=1 and x=2 MLs, while superparamagnetic behavior dominates for x=5 ML. The field-cooled magnetization-temperature M(T) curves of x=1 and x=5 MLs can be fitted by a standard three-dimensional (3D) spin-wave and a Curie–Weiss model, respectively. For x=2 ML, however, neither a 3D spin-wave nor a Curie–Weiss model, but a combination of the two fits the M-T curve. The XAS studies together with the magnetic measurements further reveal that x=1 sample behaves as a diluted magnetic semiconductor (DMS) ML, while x=2 ML shows a mixed structure consisting of a minor component of DMS and a major component of CoFe clusters. A predominant cl...