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تسجيل مستخدم جديدThe intrinsic electronic phase diagram of iron-oxypnictide superconductors
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We present the first comprehensive derivation of the intrinsic electronic phase diagram of the iron-oxypnictide superconductors in the normal state based on the analysis of the electrical resistivity $rho$ of both LaFeAsO$_{1-x}$F$_x$ and SmFeAsO$_{1-x}$F$_x$ for a wide range of doping. Our data give clear-cut evidence for unusual normal state properties in these new materials. In particular, the emergence of superconductivity at low doping levels is accompanied by distinct anomalous transport behavior in $rho$ of the normal state which is reminiscent of the spin density wave (SDW) signature in the parent material. At higher doping levels $rho$ of LaFeAsO$_{1-x}$F$_x$ shows a clear transition from this pseudogap-like behavior to Fermi liquid-like behavior, mimicking the phase diagram of the cuprates. Moreover, our data reveal a correlation between the strength of the anomalous features and the stability of the superconducting phase. The pseudogap-like features become stronger in SmFeAsO$_{1-x}$F$_x$ where superconductivity is enhanced and vanish when superconductivity is reduced in the doping region with Fermi liquid-like behavior.
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