K0.8Fe1.7SeS超导体内的畴区形貌及三维分布研究

K_0.8Fe_1.7SeS超导体内的畴区形貌及三维分布研究

陈 晓^1，2，周婷婷²，姚 湲²，王岩国²，禹日成²，段晓峰²，张志华^1*，谷 林^{2 *}

（1.大连交通大学，辽宁 大连116028；2.中国科学院物理研究所北京凝聚态国家实验室，北京100190）

摘 要：本文利用高角环形暗场像(HAADF)和衍衬像研究了K_0.8Fe_1.7SeS超导样品的超导畴区形貌及三维分布。在[001]带轴下观察到两类形貌的超导畴区，一类畴区尺寸为1mm左右，另一类为由几十纳米大小的小畴区组成的阵列。选区电子衍射和电子能量损失谱结果表明母体区对应Fe空位有序，而超导畴区可能对应K空位有序。STEM-EDS元素Mapping表明超导畴区边缘处K元素含量较多，K_0.8Fe_1.7SeS超导样品中可能至少存在三个相，分别为：K空位有序超导相、畴区外部Fe空位有序基体相以及两种空位有序区的过渡相。在[100]带轴下观察到了超导畴区具有连通性，构建了K_0.8Fe_1.7SeS超导样品中超导畴区的三维分布图。

关键词：透射电子显微镜；K_0.8Fe_1.7SeS；超导畴区形貌

中图分类号：O469；O766⁺.1；O761；TG115.21⁺5.3   文献编识码：A  doi:10.3969/j.1000-6281.2013.06.003

Morphology and three-dimensional distribution of domains in

 superconductor K_0.8Fe_1.7SeS

CHEN Xiao^1,2，ZHOU Ting-ting²，YANG Yuan²，WANG Yan-guo²，YU Ri-cheng²，

DUAN Xiao-feng²，ZHANG Zhi-hua^1* ，GU Lin^2*

(1. School of Materials Science and Engineering, Dalian Jiaotong University, Dalian Liaoning 116028；

2.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.)

Abstract:High-angle aunular dark-field (HAADF) imaging and dark-field imaging technologies were employed to study the superconducting domain morphology and its distribution in three dimensions. Two types of domain morphologes are idenfied along the [001] direction: one is the domain with size of about 1 um; the other is the array of small domain with size of tens of nanometers. Selected area electron diffraction and electron energy-loss spectroscopy indicate that the parent regions correspond to the Fe-vaccany ordering while the superconduting domains may correspond to the K-vacancy ordering. STEM-EDX Mapping experiment shows a K-rich distribution near the boundary of the domains, indicating that there are at least three phases in K_0.8Fe_1.7SeS sample. In addition, observations along the [100] direction reveal that the domains are connected, providing the direct evidence for the connectivity of superconducting domains. At last, the shematic of the three-dimensional distribution of domains is established.

Keywords:Transmission electron microscope；K_0.8Fe_1.7SeS；domain morphology

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