Direct Observation of Microstructures on Superconducting Single Crystals of K${}_x$Fe${}_{2-y}$Se${}_2$

Abstract

Potassium intercalated FeSe has been reported as a superconductor with superconducting transition temperatures ($T_{\mathrm{c}}$'s) of 30-48 K. However, there is no clear answer to identify the relationship between the surface morphology, compositional ratio and its crystal structure. This report directly reveals the correspondence among these three characteristics in single crystals with a $T_{\mathrm{c}}$ onset of around 44 K using a micro-sampling technique. Island-like parts on the surface of the crystals clearly have the K${}_x$Fe${}_2$Se${}_2$ structure with perfect FeSe layers, which is formed in conjunction with the K${}_2$Fe${}_4$Se${}_5$ phase. This results in the appearance of the $T_{\mathrm{c}}$ onset of 44 K.

arXiv comment15 pages, 6 figures

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Cited by in corpus (6)

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• Intermittent dynamics of antiferromagnetic phase in inhomogeneous iron-based chalcogenide superconductor
• Nematicity of correlated systems driven by anisotropic chemical phase separation
• Phase-separation control of K${}_x$Fe${}_{2-y}$Se${}_2$ superconductor through rapid-quenching process
• Quenching Dependence on Superconductivity in the Synthesizing Process of Single Crystals of Rb${}_x$Fe${}_{2-y}$Se${}_2$
• Formation of single-phase disordered CsxFe2-ySe2 at high pressure