Bonding states underpinning structural transitions in IrTe$_2$ observed with micro-ARPES

TL;DR

This study uses micro-ARPES to analyze the electronic structure of IrTe$_2$ during its multiple structural phase transitions, providing evidence for bonding state mechanisms driving these transitions.

Contribution

It offers the first detailed electronic structure analysis of IrTe$_2$ phases, confirming the bonding and anti-bonding states as the transition mechanism.

Findings

Identification of lowered energy states in low-temperature phases

Validation of bonding/anti-bonding states as transition drivers

Observation of phase coexistence at micron scale

Abstract

Competing interactions in low-dimensional materials can produce nearly degenerate electronic and structural phases. We investigate the staircase of structural phase transitions in layered IrTe$_2$ for which a number of potential transition mechanisms have been postulated. The spatial coexistence of multiple phases on the micron scale has prevented a detailed analysis of the electronic structure. By exploiting micro-ARPES obtained with synchrotron radiation we extract the electronic structure of the multiple structural phases in IrTe$_2$ in order to address the mechanism underlying the phase transitions. We find direct evidence of lowered energy states that appear in the low-temperature phases, states previously predicted by \textit{ab initio} calculations and extended here. Our results validate a proposed scenario of bonding and anti-bonding states as the driver of the phase transitions.