Emergence of topologically protected states in MoTe$_{2}$ Weyl semimetal with layer stacking order

TL;DR

This paper investigates how layer stacking order influences the emergence of topologically protected Weyl states in MoTe$_{2}$, revealing the transition mechanism via neutron diffraction and the role of layer displacements.

Contribution

It provides new insights into the layer stacking transition mechanism in MoTe$_{2}$ and its impact on topological properties, using neutron diffraction to elucidate the process.

Findings

Diffuse scattering indicates layer displacements during phase transition.

Layer shifts break centrosymmetry, enabling topological states.

Transition involves irreversible layer shifts along the c-axis.

Abstract

Electronic tunability in crystals with weakly-bound layers can be achieved through layer stacking order. One such example is MoTe$_2$, where the low-temperature orthorhombic T$_d$ phase is topological and host to Weyl quasiparticles. The transition mechanism to the non-trivial topology is elucidated by single crystal neutron diffraction. Upon cooling from the monoclinic 1T$\prime$ to the T$_d$ phase, diffuse scattering accompanies the transition, arising from random, in-plane layer displacements, and dissipates upon entering the T$_d$ phase. Diffuse scattering is observed only in the H0L plane due to irreversible layer shifts along the c-axis that break the centrosymmetry of the monoclinic lattice.