Effect of pressure on the structural phase transition and superconductivity in (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ ($x = 0$ and 0.45) single crystals

TL;DR

This study investigates how applying pressure up to 20 kbar influences the structural phase transition and superconductivity in (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ single crystals, revealing linear suppression of transitions and shifts in critical fields.

Contribution

It provides new insights into pressure effects on phase transitions and superconductivity in BaFe$_2$As$_2$ based compounds, especially for lightly doped and K-doped crystals.

Findings

Structural and superconducting transitions decrease linearly with pressure.

Upper critical field shifts downward in temperature under pressure.

Pressure has minimal effect on the slope of $H_{c2}(T)$.

Abstract

The effects of pressure up to $\sim 20$ kbar, on the structural phase transition of lightly Sn-doped BaFe$_2$As$_2$, as well as on the superconducting transition temperature and upper critical field of (Ba$_{0.55}$K$_{0.45}$)Fe$_2$As$_2$ single crystals have been studied. Both transitions decrease with pressure in an almost linear fashion. Under pressure, the upper critical field curve, $H_{c2}(T)$, shifts down in temperature to follow the zero field $T_c$ with very little change in slope.