Trivial and topological Fermi arcs in the type-II Weyl semimetal candidate MoTe2

Weyl semimetals are commonly identified by detecting their characteristic open surface state Fermi arcs in angle-resolved photoemission (ARPES) experiments. However, in type-II Weyl semimetals the Fermi arcs generally disappear in the bulk carrier pockets before reaching the Weyl points where they terminate - making it harder to unambiguously identify this new electronic state. Using laser-based ARPES, we have resolved multiple distinct Fermi arcs on the inequivalent top and bottom (001) surfaces of the candidate type-II Weyl semimetal MoTe$_{2}$. By comparing our ARPES data with systematic electronic structure calculations simulating different Weyl point arrangements, we show that some of these arcs are “false positives” as they can be explained without Weyl points, while others are only reproduced in scenarios with at least eight Weyl points. Our results thus suggest that MoTe$_{2}$ is the first experimental realisation of a type-II Weyl semimetal.