Pressure-temperature phase diagram of EuRbFe$_4$As$_4$ superconductor

TL;DR

This study maps the pressure-temperature phase diagram of EuRbFe$_4$As$_4$, showing how pressure suppresses superconductivity while enhancing magnetic order, with detailed measurements of critical fields and transition temperatures.

Contribution

It provides the first detailed pressure-dependent phase diagram of EuRbFe$_4$As$_4$, revealing the contrasting evolution of magnetic and superconducting transitions under pressure.

Findings

Superconducting transition temperature $T_c$ decreases monotonically with pressure.

Magnetic transition temperature $T_M$ increases linearly with pressure.

Normalized slope of the upper critical field decreases with pressure.

Abstract

The pressure dependencies of the magnetic and superconducting transitions, as well as that of the superconducting upper critical field are reported for single crystalline EuRbFe$_4$As$_4$. Resistance measurements were performed under hydrostatic pressures up to 6.21 GPa and in magnetic fields up to 9 T. Zero-field-cool magnetization measurements were performed under hydrostatic pressures up to 1.24 GPa under 20 mT applied field. Superconducting transition temperature, $T_\text c$, up to 6.21 GPa and magnetic transition temperature, $T_\text M$, up to 1.24 GPa were obtained and a pressure-temperature phase diagram was constructed. Our results show that $T_\text c$ is monotonically suppressed upon increasing pressure. $T_\text M$ is linearly increased up to 1.24 GPa. For the studied pressure range, no signs of the crossing of $T_\text M$ and $T_\text c$ lines are observed. The normalized slope of the superconducting upper critical field is gradually suppressed with increasing pressure, which may be due to the continuous change of Fermi-velocity $v_F$ with pressure.