Suppression of superconductivity and structural phase transition against pressure in Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$

TL;DR

This study investigates how applying pressure suppresses both the structural phase transition and superconductivity in a unique iron-based superconductor, highlighting the link between crystal structure and superconducting properties.

Contribution

It provides new insights into the pressure-induced suppression of superconductivity and structural transition in Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$, emphasizing the role of crystal structure.

Findings

Superconducting transition temperature $T_c$ decreases with pressure.

Structural phase transition temperature $T_s$ decreases with pressure.

Both $T_c$ and $T_s$ vanish around 0.5 GPa.

Abstract

We measured the pressure dependence of in-plane resistivity $\rho_{ab}$ in the recently-discovered iron-based superconductor Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$, which shows a unique structural phase transition in the absence of magnetic ordering, with a superconducting transition temperature $T_{\rm c}$ = 16 K and structural phase transition temperature $T_{\rm s}$ $\simeq$ 100 K at ambient pressure. $T_{\rm c}$ and $T_{\rm s}$ are suppressed on applying pressure and disappear at approximately 0.5 GPa, suggesting a relationship between superconductivity and structure. Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$ is a rather rare example in which the superconductivity appears only in a low-temperature ordered phase. The fact that the change in the crystal structure is directly linked with superconductivity suggests that the crystal structure as well as magnetism are important factors governing superconductivity in iron pnictides.