  In two-dimensional topological nodal superconductors, Majorana edge states
have been conventionally believed to exhibit only spin-triplet pairing
correlations. However, we reveal a substantial spin-singlet pairing component
in Majorana edge states of antiferromagnetic topological nodal-point
superconductors. This unexpected phenomenon emerges from the interplay between
antiferromagnetic order and symmetry, resulting in Majorana edge states with a
nearly flat band dispersion, deviating from the strictly flat band. Crucially,
this phenomenon is detectable through spin-selective Andreev reflection, where
the zero-bias conductance peaks are maximized when the spin of incident
electrons is nearly antiparallel to that of Majorana edge excitations. This
discovery unveils a unique spin signature for Andreev reflection resonances,
advancing our fundamental understanding of spin-dependent mechanisms in
topological superconductivity and representing a significant step towards the
experimental detection of Majorana fermions.
