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Superconductivity at 43 K in SmFeAsO1-xF x


Since the discovery of high-transition-temperature (high-Tc) superconductivity in layered copper oxides, extensive effort has been devoted to exploring the origins of this phenomenon. A Tc higher than 40 K (about the theoretical maximum predicted from Bardeen–Cooper–Schrieffer theory1), however, has been obtained only in the copper oxide superconductors. The highest reported value for non-copper-oxide bulk superconductivity is Tc = 39 K in MgB2 (ref. 2). The layered rare-earth metal oxypnictides LnOFeAs (where Ln is La–Nd, Sm and Gd) are now attracting attention following the discovery of superconductivity at 26 K in the iron-based LaO1-xF x FeAs (ref. 3). Here we report the discovery of bulk superconductivity in the related compound SmFeAsO1-xF x , which has a ZrCuSiAs-type structure. Resistivity and magnetization measurements reveal a transition temperature as high as 43 K. This provides a new material base for studying the origin of high-temperature superconductivity.

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Figure 1: Structural model of SmFeAsO 1- x F x with the tetragonal ZrCuSiAs-type structure.
Figure 2: X-ray diffraction pattern for a sample with nominal composition SmFeAsO1- xFx (x = 0.15).
Figure 3: Temperature dependence of magnetic susceptibility for a sample annealed at 1,160 °C.
Figure 4: Temperature dependence of resistivity with and without a magnetic field.

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This work was supported by the Natural Science Foundation of China and by the Ministry of Science and Technology of China.

Author Contributions X.H.C. designed and coordinated the whole experiment, including the details of doping and synthesis, did some of the experiments, analysed the data and wrote the paper. T.W., G.W. and R.H.L. contributed equally to the synthesis, magnetic measurements and resistive measurements under magnetic field, H.C. did the structure analysis, and D.F.F. did some of the resistive measurements.

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Correspondence to X. H. Chen.

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Chen, X., Wu, T., Wu, G. et al. Superconductivity at 43 K in SmFeAsO1-xF x. Nature 453, 761–762 (2008).

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