Absence of Local Fluctuating Dimers in Superconducting Ir$_{1-x}$(Pt,Rh)$_x$Te$_2$

TL;DR

This study investigates whether local Ir-Ir dimer fluctuations are present in superconducting IrTe2-based compounds and finds no evidence of such fluctuations, challenging theories linking dimer quantum criticality to superconductivity.

Contribution

The paper provides direct experimental evidence that local dimer fluctuations are absent in certain superconducting IrTe2 compounds, refuting the hypothesis of quantum-critical dimer fluctuations.

Findings

No nanoscale dimer fluctuations detected down to 10 K.

Local structure explained by a dimer-free model.

Results challenge the quantum-critical dimer fluctuation hypothesis.

Abstract

The compound IrTe2 is known to exhibit a transition to a modulated state featuring Ir-Ir dimers, with large associated atomic displacements. Partial substitution of Pt or Rh for Ir destabilizes the modulated structure and induces superconductivity. It has been proposed that quantum critical dimer fluctuations might be associated with the superconductivity. Here we test for such local dimer correlations and demonstrate their absence. X-ray pair distribution function approach reveals that the local structure of Ir0.95Pt0.05Te2 and Ir0.8Rh0.2Te2 dichalcogenide superconductors with compositions just past the dimer/superconductor boundary is explained well by a dimer-free model down to 10 K, ruling out the possibility of there being nanoscale dimer fluctuations in this regime. This is inconsistent with the proposed quantum-critical-point-like interplay of the dimer state and