The spin rotations and lattice rotations are locked in the Shubnikov magnetic space groups in describing magnetically ordered materials. However, real materials may contain symmetry elements whose spin and lattice operations are partially unlocked. These groups are called spin space groups and may give rise to new band structures for itinerant electrons. In the present work, we focus on potential magnetic materials in which the intrinsic electronic spin-orbit coupling is negligible. We theoretically predict many new fermionic quasiparticles at the high symmetry points (HSPs) or high symmetry lines (HSLs) in the Brillouin zone (BZ), which can neither be realized in non-magnetic systems nor in magnetic ones with Shubnikov magnetic space group symmetries. These new quasiparticles are characterized by the symmetry invariants of the little co-group, which are more essential than the representations (Reps) themselves. We also provide the dispersion around the high-symmetry points/lines, and predict a large class of nodal-point or nodal-line semimetals.
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