The layer stacking order in 2D materials strongly affects functional properties and holds promise for next generation electronic devices. In bulk, octahedral MoTe2 possesses two stacking arrangements, the Weyl semimetal Td phase, and the higher-order topological insulator 1T' phase; however, it remains unclear if thin exfoliated flakes of MoTe2 follow the Td, 1T', or an alternative stacking sequence. Here, we resolve this debate using atomic-resolution imaging within the transmission electron microscope. We find that the layer stacking in thin flakes of MoTe2 is highly disordered and pseudo-random, which we attribute to intrinsic confinement effects. Conversely, WTe2, which is isostructural and isoelectronic to MoTe2, displays ordered stacking even for thin exfoliated flakes. Our results are important for understanding the quantum properties of MoTe2 devices, and suggest that thickness may be used to alter the layer stacking in other 2D materials.
@article{arxiv.2210.16390,
title = {Emergence of Layer Stacking Disorder in c-axis Confined MoTe$_2$},
author = {James L Hart and Lopa Bhatt and Yanbing Zhu and Myung-Geun Han and Elisabeth Bianco and Shunran Li and David J Hynek and John A Schneeloch and Yu Tao and Despina Louca and Peijun Guo and Yimei Zhu and Felipe Jornada and Evan J Reed and Lena F Kourkoutis and Judy J Cha},
journal= {arXiv preprint arXiv:2210.16390},
year = {2022}
}