Origin of the phase transition in IrTe2: structural modulation and local bonding instability

TL;DR

This study investigates the structural phase transition in IrTe2, revealing a modulation and lattice change at low temperatures driven by local bonding instability related to Te 5p states, combining experimental diffraction and first principles calculations.

Contribution

The paper provides the first detailed structural analysis of IrTe2's low-temperature phase and elucidates the bonding instability as the transition's origin using combined experimental and theoretical methods.

Findings

Structural modulation with wavevector (1/5, 0, 1/5) below 285 K.

Transition from trigonal to triclinic lattice structure.

Bonding instability in Te 5p states drives the phase transition.

Abstract

We used X-ray/neutron diffraction to determine the low temperature (LT) structure of IrTe2. A structural modulation was observed with a wavevector of k =(1/5, 0, 1/5) below Ts?285 K, accompanied by a structural transition from a trigonal to a triclinic lattice. We also performed the first principles calculations for high temperature (HT) and LT structures, which elucidate the nature of the phase transition and the LT structure. A local bonding instability associated with the Te 5p states is likely the origin of the structural phase transition in IrTe2.