Multifold nodal points in magnetic materials

Understand

We describe the symmetry protected nodal points that can exist in magnetic space groups and show that only 3-, 6-, and 8-fold degeneracies are possible (in addition to the 2- and 4-fold degeneracies that have already been studied.) The 3- and 6-fold degeneracies are derived from "spin-1" Weyl fermions.

• The 8-fold degeneracies come in different flavors.
• In particular, we distinguish between 8-fold fermions that realize non-chiral "Rarita-Schwinger fermions" and those that can be described as four degenerate Weyl fermions.
• We list the (magnetic and non-magnetic) space groups where these exotic fermions can be found.