# Origins of the structural phase transitions in MoTe$_2$ and WTe$_2$

## TL;DR

This study investigates the different structural phase transitions in MoTe$_2$ and WTe$_2$ using a van der Waals density functional method, revealing that subtle differences in interlayer bonding influence their phase behavior and electronic properties.

## Contribution

The paper uncovers the microscopic origin of the contrasting phase transitions in MoTe$_2$ and WTe$_2$ through advanced computational analysis of interlayer bonding.

## Key findings

- Interlayer bonding differences cause distinct phase transitions.
- Charge doping can control structural phases.
- Structural transitions influence topological electronic properties.

## Abstract

Layered transition metal dichalcogenides MoTe$_2$ and WTe$_2$ share almost similar lattice constants as well as topological electronic properties except their structural phase transitions. While the former shows a first-order phase transition between monoclinic and orthorhombic structures, the latter does not. Using a recently proposed van der Waals density functional method, we investigate structural stability of the two materials and uncover that the disparate phase transitions originate from delicate differences between their interlayer bonding states near the Fermi energy. By exploiting the relation between the structural phase transitions and the low energy electronic properties, we show that a charge doping can control the transition substantially, thereby suggesting a way to stabilize or to eliminate their topological electronic energy bands.