Persistence of a surface state arc in the topologically trivial phase of MoTe2

The prediction of Weyl fermions in the low-temperature noncentrosymmetric $1T^{\prime }$ phase of ${\mathrm{MoTe}}_2$ still awaits clear experimental confirmation. Here, we report angle-resolved photoemission (ARPES) data and ab initio calculations that reveal a surface state arc dispersing between the valence and the conduction band, as expected for a Weyl semimetal. However, we find that the arc survives in the high-temperature centrosymmetric $1T^{\prime \prime }$ phase. Therefore, a surface Fermi arc is not an unambiguous fingerprint of a topologically nontrivial phase. We have also investigated the surface state spin texture of the $1T^{\prime }$ phase by spin-resolved ARPES, and identified additional topologically trivial spin-split states within the projected band gap at higher binding energies.