Coupling between 4f and itinerant electrons in SmFeAsO1-xFx (0.15 < x < 0.2) superconductors: an NMR study

Abstract

${}^{19}$F NMR measurements in SmFeAsO${}_{1-x}$F${}_x$, for $0.15\le x\le 0.2$, are presented. The nuclear spin-lattice relaxation rate $1/T_1$ increases upon cooling with a trend analogous to the one already observed in CeCu${}_{5.2}$Au${}_{0.8}$, a quasi two-dimensional heavy-fermion intermetallic compound with an antiferromagnetic ground-state. In particular, the behaviour of the relaxation rate either in SmFeAsO${}_{1-x}$F${}_x$ or in CeCu${}_{5.2}$Au${}_{0.8}$ can be described in the framework of the self-consistent renormalization theory for weakly itinerant electron systems. Remarkably, no effect of the superconducting transition on ${}^{19}$F $1/T_1$ is detected, a phenomenon which can hardly be explained within a single band model.

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Cited by in corpus (5)

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• Spatial Inhomogeneity in RFeAsO1-xFx (R =Pr, Nd) Determined from Rare Earth Crystal Field Excitations
• NMR Investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2As2O8-y and Ca5(Sc,Ti)4Fe2As2O11-y
• Phase separation at the magnetic-superconducting transition in La${}_{0.7}$Y${}_{0.3}$FeAsO${}_{1-x}$F${}_x$