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

TL;DR

This study synthesizes and characterizes hole-doped (Sr$_{1-x}$K$_x$)Fe$_2$As$_2$ compounds, revealing superconductivity at around 38 K and highlighting the role of hole carriers and suppression of magnetic anomalies.

Contribution

It demonstrates superconductivity in Sr$_{1-x}$K$_x$)Fe$_2$As$_2$ with a maximum T$_c$ of 38 K and provides detailed insights into the doping effects and carrier type in this compound.

Findings

Superconductivity observed at T$_c$~38 K in K-doped SrFe$_2$As$_2$

K-doping suppresses spin-density-wave anomaly

Hole carriers dominate conduction with increased carrier density

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.