Faculté des sciences

Muon spin rotation study of magnetism and superconductivity in BaFe2−xCoxAs₂ and Pr1−xSrxFeAsO

Bernhard, Christian ; Drew, Alan J. ; Schulz, Leander ; Malik, Vivek Kumar ; Rössle, Matthias ; Niedermayer, Ch. ; Wolf, Th. ; Varma, G. D. ; Mu, G. ; Wen, H.-H. ; Liu, H. ; Wu, G. ; Chen, X. H.

In: New Journal of Physics, 2009, vol. 11, p. 055050

We present a muon spin rotation (μSR) study of the magnetic and superconducting properties of single crystals of electron-doped BaFe2−xCoxAs₂ with x = 0.08, 0.20 and 0.25 (Tc = 9, 25 and 20 K) and of polycrystalline hole-doped Pr1−xSrxFeAsO with x = 0 and 0.2 (Tc = 15... Plus

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    Summary
    We present a muon spin rotation (μSR) study of the magnetic and superconducting properties of single crystals of electron-doped BaFe2−xCoxAs₂ with x = 0.08, 0.20 and 0.25 (Tc = 9, 25 and 20 K) and of polycrystalline hole-doped Pr1−xSrxFeAsO with x = 0 and 0.2 (Tc = 15 K). In the former series, we observe some interesting parallels with the electron-doped SmFeAsO1−xFx 1111-type system (Drew et al 2009 Nat. Mater. 8 310). In particular, we obtain evidence that strongly disordered static magnetism coexists with superconductivity on a microscopic scale in underdoped samples and even at optimum doping there is a slowing down (or enhancement) of dynamic magnetic correlations below Tc≈25 K. In contrast, for the hole-doped Pr1−xSrxFeAsO samples we obtain evidence for a mesoscopic phase segregation into regions with nearly unperturbed antiferromagnetic (AF) order and others that are non-magnetic and most likely superconducting. The observed trend resembles the one that was previously reported for hole-doped Ba1−xKxFe₂As₂ (Aczel et al 2008 Phys. Rev. B 78 214503, Park et al 2009 Phys. Rev. Lett. 102 117006) and thus might be a common property of the hole-doped systems.