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تسجيل مستخدم جديدOptical study on the spin-density wave properties in single crystalline Na$_{1-delta}$FeAs
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We report an optical investigation on the in-plane charge dynamics for Na$_{1-delta}$FeAs single crystal. A clear optical evidence for the spin-density wave (SDW) gap is observed. As the structural/magnetic transitions are separated in the Na$_{1-delta}$FeAs case, we find the SDW gap opens in accordance with the magnetic transition. Comparing with the optical response of other FeAs-based parent compounds, both the gap value 2$Delta$ and the energy scale for the gap-induced spectral weight redistribution are smaller in Na$_{1-delta}$FeAs. Our findings support the itinerant origin of the antiferromagnetic transition in the FeAs-based system.
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The interplay between different ordered phases, such as superconducting, charge or spin ordered phases, is of central interest in condensed matter physics. The very recent discovery of superconductivity with a remarkable T$_c$= 26 K in Fe-based oxypn
ictide La(O$_{1-x}$F$_x$)FeAs is a surprise to the scientific communitycite{Kamihara08}. The pure LaOFeAs itself is not superconducting but shows an anomaly near 150 K in both resistivity and dc magnetic susceptibility. Here we provide combined experimental and theoretical evidences showing that the anomaly is caused by the spin-density-wave (SDW) instability, and electron-doping by F suppresses the SDW instability and recovers the superconductivity. Therefore, the La(O$_{1-x}$F$_x$)FeAs offers an exciting new system showing competing orders in layered compounds.
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