Surface plasmons modulated by ferromagnetic insulating layers on the surface of topological insulator

We study the spin-polarized surface plasmons on the surface of a three-dimensional topological insulator. The surface of the topological insulator is modulated by a pulsed exchange field provided by an array of ferromagnetic insulating (FI) stripes. A nonlinear quantum hydrodynamic model is adopted and solved self-consistently, in the presence of the quantum statistical effect and the spin effect. The exchange field can form and sustain the periodic polarization of the surface plasmons under a laboratory magnetic field condition. The nonlinear effect and increasing exchange field strength enhance the surface plasmon polarization. The quantum statistical effect inhibits the surface plasmon polarization. Different spin state leads to different sign of collective density polarization.