  The magnetoelectric effect predicted in topological insulators makes
heterostructures that combine magnetic materials and such insulators promising
candidates for spintronics applications. Here, we theoretically consider a
setup that exhibits two well-separated interfaces between a topological
insulator and a ferromagnetic insulator. We show that there is a topological
magnetic dipole-dipole interaction stemming from long-range Coulomb
interactions. We analytically derive the magnetization dynamics at the two
interfaces and discuss how the long-range coupling can be applied to
non-locally induce the formation of a magnetic texture at one interface by
suitably gating the other interface.
