Superconducting properties of Mo/Si multilayer films
Superconducting properties of Mo/Si multilayer films
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Mo/Si多层薄膜的超导性能
DOI：
10.1063/1.342931
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发表时间：
1989
影响因子：
3.2
通讯作者：
H. Fujimori
中科院分区：
文献类型：
--
作者：
H. Nakajima;M. Ikebe;Y. Mutō;H. Fujimori
采用双射频磁控溅射技术制备了Mo/Si多层膜，并通过电阻测量测试了薄膜的超导转变温度T_c和上临界场Hc2。X射线衍射仪表明，当调制波长λ小于3 nm时，Mo和Si亚层均为非晶态，而当λ大于3 nm时，Mo亚层中出现晶态体心立方结构。等厚度多层膜的T_c与λ的关系表明，当λ=2.3 nm时，T_c达到最大值6.1K，接近非晶态Mo_(56)Si_(44)在小λ极限下的T_c。多层膜的超导电性被证实是由于在亚层的界面区形成了非晶态的MoSi相。根据T_c的λ关系和H_2的各向异性的结果，估计超导非晶层的厚度约为3 nm。将Mo亚层厚度控制在2.4 nm以下，以抑制薄膜的出现。
Multilayered Mo/Si thin films have been prepared by dual rf‐magnetron sputtering technique, and the superconducting transition temperature Tc and the upper critical field Hc2 have been examined by resistance measurements. X‐ray diffractometry shows that for the modulation wavelength λ shorter than 3 nm both Mo and Si sublayers are amorphous, while for λ longer than 3 nm, crystalline bcc structures appear in Mo sublayers. The λ dependence of Tc of the multilayer films with equal sublayer thickness shows that Tc takes a maximum value of 6.1 K for λ=2.3 nm and approaches the Tc value of amorphous Mo56Si44 in the small λ limit. The superconductivity of the multilayers has been confirmed to result from amorphous MoSi phase formed in the interfacial region of the sublayers. The thickness of the superconducting amorphous layer is estimated to be about 3 nm from the λ dependence of Tc and from the result of the anisotropy of Hc2 . Keeping the Mo sublayer thickness less than 2.4 nm to suppress the appearance of th...