Interplay of crystal thickness and in-plane anisotropy and evolution of quasi-one dimensional electronic character in ReSe$_{2}$

TL;DR

This study investigates how reducing the thickness of ReSe₂ crystals enhances in-plane anisotropy and promotes a more one-dimensional electronic character, using experimental and theoretical methods.

Contribution

It provides new insights into the evolution of electronic structure in ReSe₂ as a function of layer thickness, highlighting increased anisotropy and one-dimensionality in few-layer samples.

Findings

Valence band width decreases from 280 meV in bulk to 61 meV in monolayer.

In-plane anisotropy increases with decreasing layer number.

Electronic states become more one-dimensional in few-layer ReSe₂.

Abstract

We study the valence band structure of ReSe$_{2}$ crystals with varying thickness down to a single layer using nanoscale angle-resolved photoemission spectroscopy and density functional theory. The width of the top valence band in the direction perpendicular to the rhenium chains decreases with decreasing number of layers, from 280 meV for the bulk to 61 meV for monolayer. This demonstrates increase of in-plane anisotropy induced by changes in the interlayer coupling and suggests progressively more one-dimensional character of electronic states in few-layer rhenium dichalcogenides.