Structural Analysis on Iron-Based Superconductor Pr1111 System with Oxygen Deficiency and Flourine Substitution

Abstract

We have performed structural analyses on iron-based superconductors, PrFeAsO${}_{1-y}$ and PrFeAsO${}_{1-x}$F${}_x$, systematically, by means of Rietveld method on neutron powder diffraction data. The shifts of iron ion valence from +2, $\delta$, are accurately determined from the occupancies of O and O${}_{1-x}$F${}_x$ sites obtained by the Rietveld analysis and F-concentration obtained by secondary ion-microprobe mass spectrometry. $T_{\text{c}}$-$\delta$ curve of PrFeAsO${}_{1-y}$ is different from the curve of PrFeAsO${}_{1-x}$F${}_x$, indicating that $\delta$ is not a principal parameter for $T_{\text{c}}$ in so-called 1111 system. Structural parameters of the FeAs layers, for example, As-Fe-As bond angle and As-height from Fe layer, are different between both systems with similar $\delta$-values. Their parent compounds are also found to have different structural parameters, possibly due to the different synthetic conditions. These results suggest that the difference of structural parameters of FeAs layer is the origin of the discrepancy of $T_{\text{c}}$-$\delta$ curves of both systems and the $T_{\text{c}}$-value in the 1111 system is sensitive to the structural parameters. It may be attribute to an energy balance of the conducting bands contributing to the superconductivity.

7 pages, 7 figures

References in corpus (15)

• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO${}_{1-x}$F${}_x$FeAs
• Superconductivity at 22 K in Co-doped BaFe2As2 Crystals
• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Superconductivity and Phase Diagram in the Iron-based Arsenic-oxides ReFeAsO1-delta (Re = rare earth metal) without F-Doping
• Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
• Superconductivity at 52 K in iron-based F-doped layered quaternary compound Pr[O1-xFx]FeAs
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• Multiband magnetism and superconductivity in Fe-based compounds
• Electron-Hole Symmetry and Magnetic Coupling in Antiferromagnetic LaOFeAs
• Iron-based layered superconductor LaO${}_{1-x}$F${}_x$FeAs: an antiferromagnetic semimetal
• Electronic structure of heavily electron-doped BaFe${}_{1.7}$Co${}_{0.3}$As${}_2$ studied by angle-resolved photoemission
• Lattice Dynamics of LaFeAsO_{1-x}F_{x} and PrFeAsO_{1-y} via Inelastic X-Ray Scattering and First-Principles Calculation