Synchrotron X-ray Diffraction Study of Structural Phase Transition in Ca10(Ir4As8)(Fe2-xIrxAs2)

TL;DR

This study uses synchrotron X-ray diffraction to investigate a structural phase transition in Ca10(Ir4As8)(Fe2-xIrxAs2) that impacts its superconducting properties, revealing iridium ion displacements at around 100 K.

Contribution

It provides detailed structural insights into the phase transition and its relation to superconductivity in this compound, highlighting iridium ion shifts.

Findings

C-axis doubles below 100 K

Iridium ions shift along z-direction

Superconductivity at 16 K

Abstract

We report a structural transition found in Ca10(Ir4As8)(Fe2-xIrxAs2)5, which exhibits superconductivity at 16 K. The c-axis parameter is doubled below a structural transition temperature of approximately 100 K, while the tetragonal symmetry with space group P4/n (No.85) is unchanged at all temperatures measured. Our synchrotron x-ray diffraction study clearly shows iridium ions at a non-coplanar position shift along the z-direction at the structural phase transition. We discuss that the iridium displacements affect superconductivity in Fe2As2 layers.