Effect of Uniaxial Stress for Pressure-Induced Superconductor SrFe_2As_2

TL;DR

This study investigates how uniaxial stress influences the pressure-induced superconductivity in SrFe$_2$As$_2$, revealing that uniaxial stress along the c-axis lowers the critical pressure needed for superconductivity.

Contribution

It demonstrates that uniaxial stress along the c-axis significantly affects the pressure phase diagram of SrFe$_2$As$_2$, highlighting the importance of stress anisotropy in pressure-induced superconductivity.

Findings

Superconductivity appears under pressure with different critical pressures depending on the medium.

Uniaxial stress along the c-axis aids in suppressing the antiferromagnetic phase.

The critical pressure P_c decreases with less hydrostatic pressure conditions.

Abstract

We report that the pressure-temperature phase diagram of single-crystalline SrFe$_2$As$_2$ is easily affected by the hydrostaticity of a pressure-transmitting medium. For all of the three mediums we used, superconductivity with zero resistance appears, accompanied by the suppression of an antiferromagnetic (orthorhombic) phase, but the critical pressure $P_c$ was found to depend on the type of medium. $P_c$ was estimated to be 4.4 GPa under almost hydrostatic condition, but it decreased to $3.4-3.7$ GPa with the use of the medium already solidified at room temperature. The uniaxial stress along the c-axis is suggested to aid in the suppression of the antiferromagnetic (orthorhombic) phase. The pressure effect of BaFe$_2$As$_2$ is also reported.