Dynamics and mechanism of oxygen annealing in Fe${}_{1+y}$Te${}_{0.6}$Se${}_{0.4}$ single crystal

Abstract

Iron chalcogenide Fe(Te,Se) attracted much attention due to its simple structure, which is favorable for probing the superconducting mechanism. Its less toxic nature compared with iron arsenides is also advantageous for applications of iron-based superconductors. By intercalating spacer layers, superconducting transition temperature has been raised over 40 K. On the other hand, the presence of excess Fe is almost unavoidable in Fe(Te,Se) single crystals, which hinders the appearance of bulk superconductivity and causes strong controversies over its fundamental properties. Here we report a systematical study of O${}_2$-annealing dynamics in Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$ by controlling the amount of O${}_2$, annealing temperature, and time. Bulk superconductivity can be gradually induced by increasing the amount of O${}_2$ and annealing time at suitable temperatures. The optimally annealed crystals can be easily obtained by annealing with ~ 1.5% molar ratio of oxygen at 400 ${}^{\circ }$C for more than 1 hour. Superconductivity was witnessed to evolve mainly from the edge of the crystal to the central part. After the optimal annealing, the complete removal of excess Fe was demonstrated via STM measurements. Some fundamental properties were recharacterized and compared with those of as-grown crystals to discuss the influence of excess Fe.

29 pages, 10 figures

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Cited by in corpus (28)

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• Unabridged phase diagram for single-phased FeSexTe1-x thin films
• Influence of interstitial Fe to the phase diagram of Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$ single crystals
• High-field transport properties of a P-doped BaFe2As2 film on technical substrate
• Effects of heavy-ion irradiation on FeSe
• Bulk Superconductivity in Fe1+yTe0.6Se0.4 Induced by Removal of Excess Fe
• Anisotropy of iron-platinum-arsenide Ca10(PtnAs8)(Fe2-xPtxAs2)5 single crystals
• Evolution of superconducting and transport properties in annealed FeTe${}_{1-x}$Se${}_x$ (0.1 $\le$ $x$ $\le$ 0.4) multiband superconductors
• Electronic transport properties and hydrostatic pressure effect of FeSe${}_{0.67}$Te${}_{0.33}$ single crystals free of phase separation
• Comparative study of superconducting and normal-state anisotropy in Fe${}_{1+y}$Te${}_{0.6}$Se${}_{0.4}$ superconductors with controlled amounts of interstitial excess Fe
• Deviation from canonical collective creep behavior in Li${}_{0.8}$Fe${}_{0.2}$OHFeSe
• Relationships between Superconductivity and Nematicity in FeSe${}_{1-x}$Te${}_x$ ($x=0-0.5$) Films Studied by Complex Conductivity Measurements
• Importance of structural distortions in enhancement of transition temperature in FeSe${}_{1-x}$Te${}_x$ superconductors
• Tuning across the BCS-BEC crossover in the multiband superconductor Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$ : An angle-resolved photoemission study
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• Magneto-optical characterizations of FeTe${}_{0.5}$Se${}_{0.5}$ thin films with critical current density over 1 MA/cm${}^2$
• Effects of Iodine Annealing on Fe1+yTe0.6Se0.4
• Thickness-induced crossover from strong to weak collective pinning in exfoliated FeTe${}_{0.6}$Se${}_{0.4}$ thin films at 1 T
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• Removal of excess iron by annealing processes and emergence of bulk superconductivity in sulfur-substituted FeTe
• Electronic phase diagram in Te-annealed superconducting FeTe${}_{1-x}$Se${}_x$ revealed by magnetic susceptibility
• On the bad metallicity and phase diagrams of Fe${}_{1+\delta }X$ ($X$ =Te, Se, S, solid solutions): an electrical resistivity study