Field and temperature dependence of the superfluid density in LaFeAsO1-xFx superconductors: a muon spin relaxation study.
We present zero field and transverse field muon spin relaxation experiments on the recently discovered Fe-based superconductor LaFeAsO1-xFx (x=0.075 and x=0.1). The temperature dependence of the deduced superfluid density is consistent with a BCS s-wave or a dirty d-wave gap function, while the field dependence strongly evidences unconventional superconductivity. We obtain the in-plane penetration depth of lambda ab(0)=254(2) nm for x=0.1 and lambda ab(0)=364(8) nm for x=0.075. Further evidence for unconventional superconductivity is provided by the ratio of Tc versus the superfluid density, which is close to the Uemura line of high-Tc cuprates.
Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland. hubertus.luetkens@psi.ch
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Luetkens
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Klauss
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Khasanov
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Amato
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Klingeler
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Hellmann
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Leps
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Kondrat
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Hess
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Köhler
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Behr
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Werner
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Büchner