Observation of superconductivity at 30~46 K in A(x)Fe?Se?(A = Li, Na, Ba, Sr, Ca, Yb, and Eu).

ABSTRACT: New iron selenide superconductors by intercalating smaller-sized alkali metals (Li, Na) and alkaline earths using high-temperature routes have been pursued ever since the discovery of superconductivity at about 30?K in KFe?Se?, but all have failed so far. Here we demonstrate that a series of superconductors with enhanced T(c) = 30?46?K can be obtained by intercalating metals, Li, Na, Ba, Sr, Ca, Yb, and Eu in between FeSe layers by the ammonothermal method at room temperature. Analysis on their powder X-ray diffraction patterns reveals that all the main phases can be indexed based on body-centered tetragonal lattices with a?3.755-3.831 Å while c?15.99-20.54 Å. Resistivities show the corresponding sharp transitions at 45?K and 39?K for NaFe?Se? and Ba?.?Fe?Se?, respectively, confirming their bulk superconductivity. These findings provide a new starting point for studying the properties of these superconductors and an effective synthetic route for the exploration of new superconductors as well.

SUBMITTER: Ying TP 

PROVIDER: S-EPMC3361284 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature