Magnetic and Superconducting Properties of FeAs-based High-Tc Superconductors with Gd

Abstract

We report on successful synthesis under high pressure of a series of polycrystalline GdFeAs O_{1-x}F_x high-Tc superconductors with different oxygen deficiency x=0.12 - 0.16 and also with no fluorine. We have found that the high-pressure synthesis technique is crucial for obtaining almost single-phase superconducting materials: by synthesizing the same compounds with no pressure in ampoules we obtained non-superconducting materials with an admixture of incidental phases. Critical temperature for all the materials was in the range 40 to 53K. The temperature derivative of the critical field dHc2/dT is remarkably high, indicating potentially high value of the second critical field Hc2 ~ 130T.

4 pages, 4 figures

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• Electron Correlations in the Low Carrier Density LaFeAsO0.89F0.11 Superconductor (Tc = 28 K)
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• Experimental study of intrinsic multiple Andreev reflections effect in GdO(F)FeAs superconductor array junctions
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• Vortex phase dynamics in yttrium superhydride YH${}_6$ at megabar pressures
• On the Structure of Superconducting Order Parameter in High-Temperature Fe-Based Superconductors
• Multigap Superconductivity in GdFeAsO${}_{0.88}$ Evidenced by SnS-Andreev Spectroscopy
• Spatial Inhomogeneity in RFeAsO1-xFx (R =Pr, Nd) Determined from Rare Earth Crystal Field Excitations
• Estimation of intraband and interband relative coupling constants from temperature dependences of the order parameter for two-gap superconductors
• Andreev reflection spectroscopy of the new Fe-based superconductor EuAsFeO0.85F0.15: evidence for the strong order parameter anisotropy
• Direct observation of the spin exciton in Andreev spectroscopy of iron-based superconductors
• Optimization of Synthesis Parameters and Superconducting Properties of GdFeAsO1-xFx
• Study of the Two-Gap Superconductivity in GdO(F)FeAs by ScS-Andreev Spectroscopy