Crystal structure, physical properties and superconductivity in $A_x$Fe${}_2$Se${}_2$ single crystals

Abstract

We studied the correlation among structure and transport properties and superconductivity in the different $A_x$Fe${}_2$Se${}_2$ single crystals ($A$ = K, Rb, and Cs). Two sets of (00$l$) reflections are observed in the X-ray single crystal diffraction patterns, and arise from the intrinsic inhomogeneous distribution of the intercalated alkali atoms. The occurrence of superconductivity is closely related to the {\sl c}-axis lattice constant, and the $A$ content is crucial to superconductivity. The hump observed in resistivity seems to be irrelevant to superconductivity. There exist many deficiencies within the FeSe layers in $A_x$Fe${}_2$Se${}_2$, while their $T_{\mathrm{c}}$ does not change so much. In this sense, superconductivity is robust to the Fe and Se vacancies. Very high resistivity in the normal state should arise from such defects in the conducting FeSe layers. $A_x$Fe${}_2$Se${}_2$ ($A$ = K, Rb, and Cs) single crystals show the same susceptibility behavior in the normal state, and no anomaly is observed in susceptibility at the hump temperature in resistivity. The clear jump in specific heat for Rb${}_x$Fe${}_2$Se${}_2$ and K${}_x$Fe${}_2$Se${}_2$ single crystals shows the good bulk superconductivity in these crystals.

7 pages, 8 figures

References in corpus (17)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Superconductivity at 32 K in single crystal Rb${}_{0.78}$Fe${}_2$Se${}_{1.78}$}
• Synthesis and crystal growth of Cs0.8(FeSe0.98)2: a new iron-based superconductor with Tc=27K
• Microstructure and Fe-vacancy ordering in the KFexSe2 superconducting system
• Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals
• Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc = 33 K)
• Growth and characterization of A_{1-x}K_xFe_2As_2 (A = Ba, Sr) single crystals with x=0 - 0.4
• Tuning the superconducting and magnetic properties in Fe_ySe_0.25Te_0.75 by varying the Fe-content
• Superconducting and normal phases of FeSe single crystals at high pressure
• Hall effect and magnetoresistance in single crystals of NdFeAsO${}_{1-x}$F${}_x$

Cited by in corpus (26)

• Superconductivity in Iron Compounds
• The Unexpected Properties of Alkali Metal Iron Selenide Superconductors
• Nanoscale phase separation in the iron chalcogenide superconductor K0.8Fe1.6Se2 as seen via scanning nanofocused x-ray diffraction
• Electronic and magnetic phase diagram in K${}_x$Fe${}_{2-y}$Se${}_2$ superconductors
• Phase relations in K_xFe_{2-y}Se_2 and the structure of superconducting K_xFe_2Se_2 via high-resolution synchrotron diffraction
• Interplay between magnetism and superconductivity in iron-chalcogenide superconductors: crystal growth and characterizations
• Superconductivity and Magnetic Properties of high-quality single crystals of $A_x$Fe${}_2$Se${}_2$ ($A$ = K and Cs)
• Strong anisotropy in nearly ideal-tetrahedral superconducting FeS single crystals
• Superconductivity at 44 K in K intercalated FeSe system with excess Fe
• Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals
• Anisotropic magnetism, superconductivity, and the phase diagram of Rb(1-x)Fe(2-y)Se2
• The preparation and phase diagrams of (${}^7$Li${}_{1-x}$Fe${}_x$OD)FeSe and (Li${}_{1-x}$Fe${}_x$OH)FeSe superconductors
• Strong and nonmonotonic temperature dependence of Hall coefficient in superconducting K${}_x$Fe${}_{2-y}$Se${}_2$ single crystals
• Interplay between Superconductivity and Magnetism in Rb0.8Fe1.6Se2 under Pressure
• Macroscopic phase segregation in superconducting K0.73Fe1.67Se2 as seen by muon spin rotation and infrared spectroscopy
• The Pressure Effects on Electronic Structure of Iron Chalcogenide Superconductors FeSe${}_{1-x}$Te${}_x$
• Uniform Patterns of Fe Vacancy Ordering in the Kx(Fe,Co)2-ySe2 Superconductors
• Heavy Electron doping-induced antiferromagnetic phase as the parent for iron-oxypnictide superconductor LaFeAsO1-xHx
• Physical properties of $A_x$Fe${}_{2-y}$S${}_2$ ($A$=K, Rb and Cs) single crystals
• Strain effects on the electronic structure of the FeSe0.5Te0.5 superconductor
• KxFe2-ySe2 single crystals: Floating-zone growth, Transport and Structural properties
• High-pressure study of superconducting and non-superconducting single crystals of the same nominal composition Rb0.8Fe2Se2
• Compressibility and pressure-induced disorder in superconducting phase-separated Cs0.72Fe1.57Se2
• Spin excitations in K${}_{0.84}$Fe${}_{1.99}$Se${}_2$ superconductor as studied by Mössbauer spectroscopy
• Structure, superconductivity, and magnetism in Rb1-xFe1.6Se2-zSz
• Annealing Effect on Microstructure and Superconductivity of KxFeySe2 Synthesized by an Easy One-step Method