Cleaving plane-dependent electronic structures of transition metal diarsenides

Topological Dirac and Weyl semimetals are currently attracting intense interest due to their exotic physical properties. Transition metal diarsenides such as MoAs2 and WAs2 have been reported to harbor very high magnetoresistance suggesting the possible existence of a topological quantum state, although this conclusion remains dubious. Here, using systematic angle-resolved photoemission spectroscopy (ARPES) measurements and parallel first-principles calculations, we discuss the electronic structures of TAs2 (T = Mo, W). Two different cleavage planes of MoAs2 are found to harbor distinctly different surface states. Our experiments show the presence of Dirac-like dispersions on the (001) plane, which our first-principles calculations ascribe to trivial surface states. Our in-depth study also finds WAs2 to possess a trivial electronic structure. Our study emphasizes the importance of identifying the cleavage plane in low-symmetry systems and indicates that topological semimetallic states are not the key for generating high magnetoresistance in MoAs2 and WAs2.