  Spin superconductor (SSC) is an exciton condensate state where the
spin-triplet exciton superfluidity is charge neutral while spin $2(\hbar/2)$.
In analogy to the Majorana zero mode (MZM) in topological superconductors, the
interplay between SSC and band topology will also give rise to a specific kind
of topological boundary state obeying non-Abelian braiding statistics.
Remarkably, the non-Abelian geometric phase here originates from the
Aharonov-Casher effect of the "half-charge" other than the Aharonov-Bohm
effect. Such topological boundary state of SSC is bound with the vortex of
electric flux gradient and can be experimentally more distinct than the MZM for
being electrically charged. This theoretical proposal provides a new avenue
investigating the non-Abelian braiding physics without the assistance of MZM
and charge superconductor.
