Superconductivity near 55 K in fluorine-doped samarium iron oxypnictide

What changed

Ren and colleagues reported superconducting signatures in fluorine-doped samarium iron oxypnictide. Electrical resistivity began its transition at 55.0 kelvin and reached the reported zero-resistance level at 52.6 kelvin; magnetic susceptibility showed an onset of diamagnetic response at 54.6 kelvin. These observations extended the experimentally explored transition-temperature range of the layered iron-arsenide family.

Scientific scope

Ren and colleagues reported superconducting signatures in fluorine-doped samarium iron oxypnictide. Electrical resistivity began its transition at 55.0 kelvin and reached the reported zero-resistance level at 52.6 kelvin; magnetic susceptibility showed an onset of diamagnetic response at 54.6 kelvin. These observations extended the experimentally explored transition-temperature range of the layered iron-arsenide family. The reported 55 kelvin is a resistive onset, not the zero-resistance or susceptibility midpoint temperature. Diffraction indicated a principal target phase together with impurity phases; the authors cautioned that actual fluorine content could be substantially lower than the nominal composition. Measurements concern the reported polycrystalline sample, with no determination of pairing mechanism or universal temperature limit. Earlier lanthanum iron-arsenide superconductivity work is a separate contribution.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The reported 55 kelvin is a resistive onset, not the zero-resistance or susceptibility midpoint temperature. Diffraction indicated a principal target phase together with impurity phases; the authors cautioned that actual fluorine content could be substantially lower than the nominal composition. Measurements concern the reported polycrystalline sample, with no determination of pairing mechanism or universal temperature limit. Earlier lanthanum iron-arsenide superconductivity work is a separate contribution.

Contributors

• The named authors in the research record · SCIENCE: These are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.

• Superconductivity at 55 K in iron-based F-doped layered quaternary compound Sm[O1-xFx]FeAs

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