In contrast to elementary Majorana particles, emergent Majorana fermions (MFs) in
condensed-matter systems may have electromagnetic multipoles. We developed a general
theory of magnetic multipoles for helical MFs on time-reversal-invariant superconductors.
The results show that the multipole response is governed by crystal symmetry, and that a
one-to-one correspondence exists between the symmetry of Cooper pairs and the
representation of magnetic multipoles under crystal symmetry. The latter property provides a …

Crystalline symmetry enriches topological phases of matter. For instance, Dirac semimetals
with crystalline symmetry are one of the promising ways to realize a variety of topological
superconductivity. In contrast to elementary Majorana particles, emergent Majorana
fermions (MFs) in topological crystalline supercondutors may have electromagnetic
multipoles. We developed a general theory of magnetic multipoles for surface helical MFs on
time-reversal-invariant superconductors. The results show that the multipole response is …