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arXiv 1706.02182cond-mat.supr-con
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$_x$ Fe $_{2-y}$-Se $_2$中空位无序边界处的超导电性

Superconductivity at the vacancy disorder boundary in K$_x$Fe$_{2-y}$Se$_2$

Chunruo Duan, Junjie Yang, Yang Ren, Despina Louca

摘要:

本文重新讨论了相分离在碱金属掺杂铁硒化物中超导电性出现中的作用。用高能X射线衍射和Monte Carlo模拟方法研究了淬火超导(SC)和生长态非超导(NSC)KPDMATHABMM Fe $_{2-y}$ Se $_{2}$单晶的晶体结构。在SC和NSC晶体中观察到了面内$\sqrt{2}\times\sqrt{2}$ K空位有序和$\sqrt{5}\times\sqrt{5}$ Fe空位有序的超晶格结构与无\textit{I4/mmm} Fe空位相共存。此外,在SC晶体中还存在Fe空位无序相。它出现在\textit{I4/mmm}无空位相和\textit{I4/m}空位有序相($\sqrt{5}\times\sqrt{5}$)之间的边界处。空位无序相最有可能是超导电性的主体。

英文摘要:

The role of phase separation in the emergence of superconductivity in alkali metal doped iron selenides A$_{x}$Fe$_{2-y}$Se$_{2}$ (A = K, Rb, Cs) is revisited. High energy X-ray diffraction and Monte Carlo simulation were used to investigate the crystal structure of quenched superconducting (SC) and as-grown non-superconducting (NSC) K$_{x}$Fe$_{2-y}$Se$_{2}$ single crystals. The coexistence of superlattice structures with the in-plane $\sqrt{2}\times\sqrt{2}$ K-vacancy ordering and the $\sqrt{5}\times\sqrt{5}$ Fe-vacancy ordering were observed in SC and NSC crystals along side the \textit{I4/mmm} Fe-vacancy free phase. Moreover, in the SC crystal an Fe-vacancy disordered phase is additionally present. It appears at the boundary between the \textit{I4/mmm} vacancy free phase and the \textit{I4/m} vacancy ordered phase ($\sqrt{5}\times\sqrt{5}$). The vacancy disordered phase is most likely the host of superconductivity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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