Prediction of Weyl semimetal in orthorhombic MoTe2

We investigate the orthorhombic phase (T_d) of the layered transition-metal dichalcogenide MoTe₂ as a Weyl semimetal candidate. MoTe₂ exhibits four pairs of Weyl points lying slightly above (∼6 meV ) the Fermi energy in the bulk band structure. Different from its cousin WTe₂, which was recently predicted to be a type-II Weyl semimetal, the spacing between each pair of Weyl points is found to be as large as 4% of the reciprocal lattice in MoTe₂ (six times larger than that of WTe₂). When projected onto the surface, the Weyl points are connected by Fermi arcs, which can be easily accessed by angle-resolved photoemission spectroscopy due to the large Weyl point separation. In addition, we show that the correlation effect or strain can drive MoTe₂ from a type-II to a type-I Weyl semimetal.