Prediction of the Weyl semimetal in the orthorhombic MoTe2

TL;DR

This paper predicts that orthorhombic MoTe2 is a Weyl semimetal with large Weyl point separation, and discusses how strain or correlations can switch its type, providing insights for experimental verification.

Contribution

It is the first detailed theoretical prediction of Weyl points and Fermi arcs in orthorhombic MoTe2, highlighting its potential as a large-separation Weyl semimetal.

Findings

MoTe2 has four pairs of Weyl points slightly above the Fermi level.

Weyl points are connected by observable Fermi arcs.

Strain or correlation effects can induce a transition from type-II to type-I Weyl semimetal.

Abstract

We investigate the orthorhombic phase (Td) of layered transition-metal-dichalcogenide MoTe$_2$ as a Weyl semimetal candidate, which was discovered to be a superconductor in our recent experiment. MoTe$_2$ exhibits four pairs of Weyl points lying slightly ($\sim$ 6 meV) above the Fermi energy in the bulk band structure. Unlike its cousin WTe$_2$, which was predicted to be a type-II Weyl semimetal recently, the spacing between each pair of Weyl points is found to be as large as 4 percent of the reciprocal lattice in MoTe$_2$ (six times larger than that of WTe$_2$). When projected to the surface, Weyl points are connected by Fermi arcs, which can be easily verified by ARPES due to the large Weyl point separation. In addition, we show that the correlation effect or strain can drive MoTe$_2$ from the type-II to type-I Weyl semimetal.