铁基材料K<sub<x</sub<Fe<sub<2-y</sub<Se<sub<2</sub<中一种可能的超导基态相K<sub<2</sub<Fe<sub<7</sub<Se<sub<8</sub<的发现
K<sub<2</sub<Fe<sub<7</sub<Se<sub<8</sub<：A possible parent phase for superconductivity in iron-based material K<sub<x</sub<Fe<sub<2-y</sub<Se<sub<2</sub<
-
摘要: 铁基超导体的发现开启了探索超导材料的新一轮热潮。最新发现的铁基超导体KxFe2-ySe2有着许多不同寻常的性质。此材料中明显存在相分离，材料中主要的部分是具有反铁磁性质的绝缘相K<sub<2</sub<Fe<sub<4</sub<Se<sub<5</sub<，，超导相只占少量体积。但是超导相在物理上很重要，因为根据理论计算，该材料中不存在空穴型费米面，这样该领域中被广泛接受的S<sup<±</sup<; 配对图像似乎受到挑战。相分离的存在致使此材料中相关研究的难度非常大。该文介绍了此材料中超导相的探索和研究，确认了此材料的超导相是以三维网络状的细丝形态存在，并提出超导的母体相可能是每8个Fe位置有一个Fe空位形成的√8× √10这种有序平行四边形结构，称为K<sub<2</sub<Fe<sub<7</sub<Se<sub<8</sub<相。Abstract: The search for new superconducting materials has been spurred on by the discovery of iron-based superconductors whose structure and composition is qualitatively different from the cuprates. The study of one such material，K<sub<x</sub<Fe<sub<2-y</sub<Se<sub<2</sub< with a critical temperature of 32 K，is made more difficult by the fact that it separates into two phases- a dominant antiferromagnetic insulating phase K<sub<2</sub<Fe<sub<4</sub<Se<sub<5</sub<，and a minority superconducting phase. In this paper，we identify a three-dimensional network of superconducting filaments within this material and present evidence to suggest that the superconducting phase consists of a single Fe vacancy of every eight Fe-sites arranged in a √8× √10 paral⁃lelogram structure.
下载: