X-ray induced electronic structure change in CuIr$_2$S$_4$

TL;DR

This study uses advanced x-ray spectroscopic techniques to investigate how x-ray irradiation affects the electronic structure of CuIr₂S₄, revealing charge-density-wave gap formation and disorder-induced spectral features.

Contribution

It provides the first detailed spectroscopic analysis of x-ray induced electronic structure changes in CuIr₂S₄, confirming theoretical predictions and identifying new disorder-related spectral features.

Findings

Charge-density-wave gap opens below 230 K as observed by RIXS.

X-ray irradiation induces a disordered phase with a broad spectral peak around 0.4 eV.

Electronic structure modifications are consistent with density functional theory predictions.

Abstract

The electronic structure of CuIr$_2$S$_4$ has been investigated using various bulk-sensitive x-ray spectroscopic methods near the Ir $L_3$-edge: resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy in the partial fluorescence yield (PFY-XAS) mode, and resonant x-ray emission spectroscopy (RXES). A strong RIXS signal (0.75 eV) resulting from a charge-density-wave gap opening is observed below the metal-insulator transition temperature of 230 K. The resultant modification of electronic structure is consistent with the density functional theory prediction. In the spin- and charge- dimer disordered phase induced by x-ray irradiation below 50 K, we find that a broad peak around 0.4 eV appears in the RIXS spectrum.