A rotor stack of an electric motor may include a gap for insertion of at least two permanent magnets of an individual magnet pole. The gap may include a central connecting element and at least two side connecting elements, which mechanically connect an inner part and an outer part of the rotor stack, so that the at least two side connecting elements define an air barrier having a form of a polygon. The air barrier in an outer corner of the gap may extend to at least two side of a respective one of the at least two permanent magnets. According to an implementation, the respective permanent magnets may be configured as a cuboid.