Spin signature of majorana fermions in topological nodal-point superconductors

Abstract

In two-dimensional topological nodal superconductors, Majorana edge states have been conventionally believed to exhibit spin-triplet pairing correlations. Here, we show that a substantial spin-singlet pairing component is present in Majorana edge states of antiferromagnetic topological nodal-point superconductors. We reveal that this unexpected phenomenon emerges from the interplay of antiferromagnetic order and symmetry, which leads to Majorana edge states manifesting with nearly flat bands instead of strictly flat bands. Crucially, it can be detectable by means of spin-dependent Andreev reflection, where the zero-bias conductance peaks are maximized when the spin of incident electrons is nearly antiparallel to that of the Majorana edge excitations. Our findings unveil a unique spin signature for Andreev reflection resonances, thus advancing our fundamental understanding of spin-dependent mechanisms in topological superconductivity and representing a significant step towards the experimental detection of Majorana fermions.