Local structural disorder and superconductivity in KxFe2-ySe2

Abstract

We report significantly enhanced magnetic moment in K0.69(2)Fe1.45(1)Se2.00(1) single crystals with sharp Tc and bulk superconductivity obtained by postannealing and quenching process. There are two Fe sites in the K0.69(2)Fe1.45(1)Se2.00(1) unit cell: Fe1, which has higher symmetry with longer average Fe-Se bond length, and Fe2, which has lower symmetry with shorter average Fe-Se bond length. Temperature-dependent x-ray absorption fine-structure (XAFS) analysis results on quenched and as-grown K0.69(2)Fe1.45(1)Se2.00(1) crystals show that quenched K0.69(2)Fe1.45(1)Se2.00(1) have increased average Fe-Se bond length and decreased static disorder. Our results indicate that nonzero population of Fe1 sites is the key structural parameter that governs the bulk superconductivity. We also show clear evidence that Fe1 sites carry higher magnetic moment than Fe2 sites.

3 figures, 4 pages

References in corpus (6)

• Tellurium substitution effect on superconductivity of the alpha-phase Iron Selenide
• Superconductivity in S-substituted FeTe
• Nanoscale phase separation in the iron chalcogenide superconductor K0.8Fe1.6Se2 as seen via scanning nanofocused x-ray diffraction
• Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (Tc= 31.8 K) single crystals
• Anisotropy in transport and magnetic properties of K0.64Fe1.44Se2
• Temperature dependent local structure of NdFeAsO1-xFx system using arsenic K-edge extended x-ray absorption fine structure

Cited by in corpus (12)

• Fe-vacancy order and superconductivity in PbO-type tetragonal β-Fe1-xSe
• Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals
• Effective doping and suppression of Fermi surface reconstruction via Fe vacancy disorder in KxFe2-ySe2
• Optical conductivity of iron-based superconductors
• Superconductivity and magnetism in RbxFe2-ySe2: Impact of thermal treatment on mesoscopic phase separation
• Correlated disorder to order crossover in the local structure of K${}_x$Fe${}_{2-y}$Se${}_{2-z}$S${}_z$
• Competing striped structures in La2CuO4+y
• Superconductivity at the vacancy disorder boundary in K${}_x$Fe${}_{2-y}$Se${}_2$
• Spin dynamics of the spin chain antiferromagnet RbFeS${}_2$
• $\mathrm{L}{\mathrm{i}}_{\mathrm{x}}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{\mathrm{y}}\mathrm{F}{\mathrm{e}}_{2-\mathrm{z}}\mathrm{S}{\mathrm{e}}_2$: a defect resilient expanded-lattice high-temperature superconductor
• In-situ visualization of local distortions in the high-$T_c$ molecule-intercalated $L{i}_x(C_5{H}_{5}N{)}_{y}F{e}_{2-z}S{e}_2$ superconductor
• Multiband behavior and non-metallic low-temperature state of K${}_{0.50}$Na${}_{0.24}$Fe${}_{1.52}$Se${}_2$