  Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked
enormous research interest recently. Possessing unique Weyl fermions in the
bulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing
many exotic physical phenomena. TWSs can be classified into type-I that respect
Lorentz symmetry and type-II that do not. Here, we directly visualize the
electronic structure of MoTe2, a recently proposed type-II TWS. Using
angle-resolved photoemission spectroscopy (ARPES), we unravel the unique
surface Fermi arcs, in good agreement with our ab-initio calculations. From
spin-resolved ARPES measurements, we demonstrate the non-degenerate
spin-texture of surface Fermi-arcs, thereby proving their non-trivial
topological nature. Our work not only lead to new understandings of the unusual
properties discovered in this family of compounds, but also allow for the
further exploration of exotic properties and practical applications of type-II
TWSs, as well as the interplay between superconductivity (MoTe2 was discovered
to be superconducting recently) and their topological order.
