  We theoretically investigate the surface plasmon polariton (SPP) at the
interface between 3D strong topological insulator (TI) and layered
superconductor-magnetic insulator structure. The tunability of SPP through
electronic doping can be enhanced when the magnetic permeability of the layered
structure becomes higher. When the interface is gapped by superconductivity or
perpendicular magnetism, SPP dispersion is further distorted, accompanied by a
shift of group velocity and penetration depth. Such a shift of SPP reaches
maximum when the magnitude of Fermi level approaches the gap value, and may
lead to observable effects. The tunable SPP at the interface between layered
superconductor and magnetism materials in proximity to TI surface may provide
new insight in the detection of Majorana Fermions.
