Coexistence of different electronic phases in the K0.8Fe1.6Se2 superconductor: a bulk-sensitive hard x-rays spectroscopy study

Abstract

We have studied electronic and magnetic properties of the K0.8Fe1.6Se2 superconductor by x-ray absorption and emission spectroscopy. Detailed temperature dependent measurements alongwith a direct comparison with the binary FeSe system have revealed coexisting electronic phases: a majority phase with high spin 3+Fe state and a minority phase with intermediate spin 2+Fe state. The effect of high temperature annealing suggests that the compressed phase with lower spin 2+Fe state is directly related with the high Tc superconductivity in the title system. The results clearly underline glassy nature of superconductivity in the electronically inhomogeneous K0.8Fe1.6Se2, similar to the superconductivity in granular phases.

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• Spectromicroscopy of electronic phase separation in K${}_x$Fe${}_{2-y}$Se${}_2$ superconductor
• Superconductivity and magnetism in RbxFe2-ySe2: Impact of thermal treatment on mesoscopic phase separation
• Local and collective magnetism of EuFe${}_2$As${}_2$
• Temperature dependence of iron local magnetic moment in phase-separated superconducting chalcogenide
• Origin of Pressure-induced Superconducting Phase in K${}_x$Fe${}_{2-y}$Se${}_2$ studied by Synchrotron X-ray Diffraction and Spectroscopy
• Effective medium approximation and the complex optical properties of the inhomogeneous superconductor K_{0.8}Fe_{2-y}Se_2
• Magnetic moment evolution and spin freezing in doped BaFe${}_2$As${}_2$
• $\mathrm{L}{\mathrm{i}}_{\mathrm{x}}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{\mathrm{y}}\mathrm{F}{\mathrm{e}}_{2-\mathrm{z}}\mathrm{S}{\mathrm{e}}_2$: a defect resilient expanded-lattice high-temperature superconductor
• Annealing Effect on Microstructure and Superconductivity of KxFeySe2 Synthesized by an Easy One-step Method
• Fluctuating magnetism of Co- and Cu-doped NaFeAs