Ferromagnetic spin fluctuation in LaFeAsO1-xFx

Abstract

The F doped LaFeAsO, a recently discovered superconductor with the high Tc of 26 K, has been studied by the resistivity, magnetic susceptibility, and heat capacity measurements in the F doping range from 0 to 0.14 (x in LaFeAsO1-xFx). In the low temperature region, a T3lnT term in the heat capacity and a T2 term in the magnetic susceptibility, which are derived from the spin fluctuation, are observed. The nearly ferromagnetic nature evidenced by a large Wilson ratio (6.5 for x = 0, and 11.2 for x = 0.025) suggests that the superconductivity in the LaFeAsO system is mediated by ferromagnetic spin fluctuation.

13 pages, 4 figures

References in corpus (4)

• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• Very High Field Two-Band Superconductivity in LaFeAsO_0.89F_0.11
• Itinerant Ferromagnetism in layered crystals LaCoOX (X = P, As)
• Intrinsic Properties of Stoichiometric LaOFeP

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• Pressure-induced shift of T${}_c$ in K${}_x$Sr${}_{1-x}$Fe${}_2$As${}_2$ (x=0.2, 0.4, 0.7): Analogy to the high-T${}_c$ cuprate superconductors
• The superconductor KxSr(1-x)Fe2As2: Normal state and superconducting properties
• Systematic ^{75}As NMR study of the dependence of low-lying excitations on F doping in the iron oxypnictide LaFeAs(O_{1-x}F_{x})
• Evidence for Local Moment by Electron Spin Resonance Study on Polycrystalline LaFeAsO${}_{1-x}$F${}_x$ (x=0 and 0.13)
• Mechanism of phase transitions and the electronic density of states in (La,Sm)FeAsO${}_{1-x}$F${}_x$ from ab initio calculations