Unconventional charge-density wave in Sr3Ir4Sn13 cubic superconductor revealed by optical spectroscopy study

TL;DR

This study uses optical spectroscopy to investigate Sr3Ir4Sn13, revealing an unusual spectral weight transfer and an energy gap-like feature associated with a structural phase transition, indicating complex electron correlation effects beyond typical charge density waves.

Contribution

It provides new insights into the electronic structure changes and correlation effects in Sr3Ir4Sn13 during its structural phase transition, highlighting unconventional phenomena.

Findings

Spectral weight transfer occurs over a broad energy scale.

An energy gap-like suppression appears below the transition temperature.

Suppression energy scale exceeds that of typical charge density waves.

Abstract

Sr3Ir4Sn13 is an interesting compound showing a coexistence of structural phase transition and superconductivity. The structural phase transition at 147 K leads to the formation of a superlattice. We performed optical spectroscopy measurements across the structural phase transition on single crystal sample of Sr3Ir4Sn13. The optical spectroscopy study reveals an unusual temperature induced spectral weight transfer over broad energy scale, yielding evidence for the presence of electron correlation effect. Below the structural phase transition temperature an energy gap-like suppression in optical conductivity was observed, leading to the removal of partial itinerant carriers near Fermi level. Unexpectedly, the suppression appears at much higher energy scale than that expected for a usual charge density wave phase transition.