Orbital Degeneracy and Peierls Instability in Triangular Lattice Superconductor Ir$_{1-x}$Pt$_x$Te$_2$

TL;DR

This study investigates how orbital and charge instabilities in a triangular lattice superconductor are suppressed by Pt doping, revealing the role of an orbitally-induced Peierls effect in the emergence of superconductivity.

Contribution

It demonstrates that Pt doping suppresses charge and orbital modulations in IrTe$_2$, highlighting the orbitally-induced Peierls effect as key to understanding its superconductivity.

Findings

Pt doping suppresses Ir 5d charge modulation

Charge modulation is linked to Ir 5d orbital reconstruction

Orbitally-induced Peierls effect governs charge and orbital instability

Abstract

We have studied electronic structure of triangular lattice Ir$_{1-x}$Pt$_x$Te$_2$ superconductor using photoemission spectroscopy and model calculations. Ir $4f$ core-level photoemission spectra show that Ir $5d$ $t_{2g}$ charge modulation established in the low temperature phase of IrTe$_2$ is suppressed by Pt doping. This observation indicates that the suppression of charge modulation is related to the emergence of superconductivity. Valence-band photoemission spectra of IrTe$_2$ suggest that the Ir $5d$ charge modulation is accompanied by Ir $5d$ orbital reconstruction. Based on the photoemission results and model calculations, we argue that the orbitally-induced Peierls effect governs the charge and orbital instability in the Ir$_{1-x}$Pt$_x$Te$_2$.