Superconductivity in hole-doped (Sr${}_{1-x}$K${}_x$)Fe${}_2$As${}_2$

Abstract

A series of layered (Sr${}_{1-x}$K${}_x$)Fe${}_2$As${}_2$ compounds with nominal x=0 to 0.40 are synthesized by solid state reaction method. Similar to other parent compounds of iron-based pnictide superconductors, the pure SrFe${}_2$As${}_2$ shows a strong resistivity anomaly near 210 K, which was ascribed to the spin-density-wave instability. The anomaly temperature is much higher than those observed in LaOFeAs and BaFe${}_2$As${}_2$, the two prototype parent compounds with ZrCuSiAs- and ThCr${}_2$Si${}_2$-type structures. K-doping strongly suppresses this anomaly and induces superconductivity. Like in the case of K-doped BaFe${}_2$As${}_2$, sharp superconducting transitions at T${}_c\sim$38 K was observed. We performed the Hall coefficient measurement, and confirmed that the dominant carriers are hole-type. The carrier density is enhanced by a factor of 3 in comparison to F-doped LaOFeAs superconductor.

3 pages, 3 figures