Fermi arcs in topological chiral crystals*

The telltale trademarks of a Weyl semimetal are the topologically protected Fermi arc surface states. While these surface states have been demonstrated in conventional Weyl semimetals (for instance, the TaAs family), they should also be present in the recently proposed unconventional Weyl semimetals. However, there is still a lack of candidate materials for experimental exploration. In this talk, we comment on a number of chiral crystals in space group No. 198, as platforms for expanding the list of Fermi arc materials. Notably, RhSi, CoSi, CoGe, RhGe, AlPd, AlPt, BaPtP, and BaPtAs constitute promising candidate materials. Indeed, these compounds should exhibit the longest possible Fermi arcs, spanning across the entire surface Brillouin zone. These predictions are closely tied to the maximally separated 4-fold and 6-fold unconventional chiral fermions that have recently been predicted in this class of compounds. We further comment on experimental progress and the current challenges in using ARPES to observe a chiral Weyl semimetal phase with Fermi arcs in these materials.