Dimensional crossover of charge order in IrTe$_2$ with strong interlayer coupling

TL;DR

This study investigates how charge order in IrTe$_2$ transitions from two-dimensional to quasi-three-dimensional as the material's thickness increases, revealing a gradual phase change and interface effects using advanced microscopy techniques.

Contribution

It provides the first experimental observation of a dimensional crossover of charge order in IrTe$_2$ from monolayer to multilayer, highlighting the role of interlayer coupling and substrate effects.

Findings

Charge order transitions from 2D to quasi-3D with increasing thickness.

Exponential decay of Coulomb gap as layer number increases.

Suppression of density of states at 2D-3D interfaces.

Abstract

Tuning dimensionality in van der Waals materials with finite interlayer coupling has introduced various electronic phase transitions by conventional mechanical exfoliation. Particularly when the electronic order is tied to the modulation of the interlayer coupling, such dimensional tunability has a strong impact on its stability and properties, which has rarely been investigated experimentally. Here, we demonstrate a dimensional crossover of charge order in IrTe$_2$ from genuine two- to quasi-three-dimension using low-temperature scanning tunneling microscopy and spectroscopy. Employing atomically thin IrTe$_2$ flakes ranging from monolayer to multilayer, we observe a gradual phase transition of charge order and exponential decay of Coulomb gap with increasing thickness. Moreover, we find a suppression of the density of states emerging at an abrupt lateral interface between two- and three-dimension. These findings are attributed to the interplay between the strongly coupled layers and substrate-driven perturbation, which can provide a new insight into the dimensional crossover of strongly coupled layered materials with hidden electronic phases.