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Superconductivity at the vacancy disorder boundary in K$_x$Fe$_{2-y}$Se$_2$
- Source :
- Phys. Rev. B 97, 184502 (2018)
- Publication Year :
- 2017
-
Abstract
- 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.<br />Comment: 5 pages, 3 figures, 2 tables
- Subjects :
- Condensed Matter - Superconductivity
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 97, 184502 (2018)
- Publication Type :
- Report
- Accession number :
- edsarx.1706.02182
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.97.184502