Fragility of Fermi arcs in Dirac semimetals*

We use tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy and density functional theory calculations to study the electronic properties of Dirac semimetal candidate PtBi₂. In addition to bulk electronic states we also find surface states as expected from theory and band calculations. The topological surface states form Fermi pockets rather than double Fermi arcs that were observed in Na₃Bi. The surface bands forming the Fermi pockets merge with bulk bands in proximity of the Dirac points projections, as expected. Our data confirms existence of Dirac states in PtBi₂ and reveals the fragility of the Fermi arcs in Dirac semimetals. Because the Fermi arcs are not topologically protected in general, they can be deformed into Fermi pockets, as proposed by Kargarian et al.. Our results demonstrate validity of this theory in PtBi₂