  Nodal-point and Nodal-line structures in the dispersion of electron energy
bands are characterized by their high degeneracy in certain corners or lines in
the Brillouin zone (BZ). These nodal structures can also exist in the
dispersion of itinerant electrons in magnetically ordered materials whose
symmetry groups are anti-unitary groups called the magnetic space groups. In
the present work, we provide a complete list of magnetic space groups which can
host symmetry-protected nodal-point/line band structures for spin-1/2 fermionic
particles, where the degeneracies at the nodal points/lines are guaranteed by
irreducible projective representations (IPReps) of the little co-groups. Our
discussion is restricted to the magnetic space groups whose magnetic point
group contains the space-time inversion operation $\tilde T=\mathcal IT$, the
combined operation of spacial inversion $\mathcal I$ and time reversal $T$,
such that the energy bands are at least doubly-degenerate at arbitrary points
in the BZ. For these magnetic point groups we provide the invariants to label
the classes of projective Reps, and for each class we calculate all the
inequivalent IPReps. From the results we select out all the groups and the
corresponding Rep classes which support high-dimensional ($d\geq$4) IPReps. We
then list the magnetic space groups and their high symmetry points/lines whose
little co-groups have high-dimensional ($d\geq$4) IPReps with the corresponding
factor systems. Examples of candidate materials are discussed.

Mesoscale and Nanoscale Physics;Strongly Correlated Electrons