Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)

TL;DR

This study investigates how applying pressure affects the superconducting transition temperature in a rare-earth doped iron pnictide, revealing a pressure-induced increase and a maximum T_c of about 44 K.

Contribution

It demonstrates that pressure can be used to tune T_c in Ca$_{0.73}$La$_{0.27}$Fe$_2$As$_2$, showing a superconducting dome with a peak at 20 kbar, which is a novel control method.

Findings

T_c increases steeply with pressure initially.

Maximum T_c of ~44 K at 20 kbar.

Pressure tuning offers an independent method to modify T_c.

Abstract

We report measurements of the pressure dependence of the superconducting transition temperature T_c in single crystal samples of the rare-earth doped superconductor Ca$_{0.73}$La$_{0.27}$Fe$_2$As$_2$. We track T_c with two techniques, via in-plane resistivity measurements and with a resonant tunnel diode oscillator circuit which is sensitive to the skin depth. We show that initially T_c rises steeply with pressure, forming a superconducting dome with a maximum T_c of ~44 K at 20 kbar. We discuss this observation in the context of other electron-doped iron pnictide superconductors, and conclude that the application of pressure offers an independent way to tune T_c in this system.